MCBa EngineerVol 231 No 3

Octl Nov1977

advanced communications for the nineteen -eighties

Our cover is an interpretation ofworldwide communications byBob Canary, who is a graphicdesigner at ATL in Camden, N.J.

MICEa EngineerA technical journal published byRCA Research and EngineeringBldg. 204-2Cherry Hill, N.J. 08101Tel. PY-4254 (609-779-4254)Indexed annually in the Apr/May issue.

John PhillipsBill LaufferJoan ToothillFrank StroblPat Gibson

Joyce Davis

Jay Brandinger

John Christopher

Bill Hartzell

Jim Hepburn

Hans Jenny

Arch Luther

Howie Rosenthal

Carl Turner

Bill Underwood

Joe Volpe

Bill Webster

Ed Burke

Walt Dennen

Charlie Foster

RCA Engineer Staff

EditorAssistant EditorArt Editor

Contributing EditorCompositionEditorial Secretary

Editorial Advisory Board

Div. VP, Engineering,Consumer ElectronicsVP, Tech. OperationsRCA AmericomDiv. VP, EngineeringPicture Tube Division

VP and Technical Director,Globcom

Manager, TechnicalInformation ProgramsChief Engineer,Broadcast Systems

Staff VP, EngineeringDiv. VP, Solid StatePower Devices

Director, EngineeringProfessional ProgramsChief Engineer,Missile and Surface RadarVP, Laboratories

Consulting Editors

Ldr., Presentation Services,Missile and Surface Radar

Mgr., News and Information,Solid State DivisionMgr., Scientific Publications,Laboratories

To disseminate to RCA engineers technical information ofprofessional value To publish in an appropriate manner important technicaldevelopments at RCA. and the role of the engineerTo serve as a medium of interchange of technical informationbetween various groups at RCA To create a community of engineering interest within the companyby stressing the interrelated nature of all technical contributions To help publicize engineering achievements in a manner that willpromote the interests and reputation of RCA in the engineering field To provide a convenient means by which the RCA engineer mayreview his professional work before associates and engineeringmanagement

To announce outstanding and unusual achievements of RCAengineers in a manner most likely to enhance their prestige andprofessional status.

RCA's communications environmenteconomics is as big a challenge as climate and terrain

This is the 20th anniversary of Sputnik-a perceived threat that galvanized us into anational technical effort unmatched in peacetime.

One unforeseen benefit of that effort was satellite -aided communications-atechnological, social, political, and economic development of global importance.For RCA, this has changed the communications business substantially. We nowhave three important communications companies-Alascom, Americom, andGlobcom-all of which have benefited significantly from the space effort.

Although my own association with these companies dates back only severalmonths, two initial impressions remain with me from almost my first day. First, RCAengineers have designed and developed technically unsurpassed communicationssystems and often have operated these facilities in forbidding climates and onrigorous terrains. Second, RCA management has authorized enormous capitalexpenditures to develop the state-of-the-art equipment and facilities for these threecommunications companies.

RCA scientists and engineers can be justly proud of their accomplishments, but atremendous engineering frontier is still open. Satellite and associated groundtechnology are new and glamorous; yet the more prosaic cable and switchingengineering field probably has the potential for just as high "payback." And, as Ilook ahead, "payback" will be the primary criterion in determining future designand development engineering priorities in the communications business.

But the RCA engineering community is no stranger to an environment where cost-effective performance is the prime requisite. And you can be sure that I will join withyou in carrying forward such engineering programs. It is vital to our continued jointsuccess.

Julius KoppelmanGroup Vice PresidentRCA CorporationCherry Hill, N.J.

advanced communications for the 1980sThree trends are increasing the efficiency and capacity of thecommunications industry. All three ideas-digital communi-

cation, automation, and communication satellites-havebeen with us for some time, but their increased use is nowaffecting the industry and RCA strongly.

- keeping technically current

- satellite communications

Satellites now have mor4 communication capacitythan all the transoceanic cables now installed.

- digital communication

4, 12, 40, 52 -

Digital equipment costs less, noise is notcumulative, encryption is easier, and digital systemscan handle many types of transmission (voice, data,music) simultaneously.

4, 36, 40 -

automated operations and managementOver 80% of RCA Globcom's overseas telex calls nowmove through a computerized system; automatedcircuit management will soon maintain the entireGlobcom system.

Remember that survey? How do RCA's engineersobtain new technical information and stay up to date?Where do you stand?

Coming upOur next issue (Dec/Jan) covers the broadcast end of advanced communications,including digital tv, circular polarization, and electronic journalism.

Later issues will have radar, software, and space technology themes.

K.H. Powers

H. Staras

J.E. Keigler1D.S. Bond

H.K. Jenny

J.C. Hepburn

E.S. Rogers1R.J. Klensch

H.K. Jenny1W.J. Underwood

H.E. White

J.L. Santoro1J.B. Howe

F.N. Sechil H.C. Huang

D.D. Harbert1R.G. Ferrie

A. Acampora

D. Mishral A. Devarajan

H.Khajezadehl B.J. Walmsley

T.F. Lenihan

Copyright 1977 RCA CorporationAll rights reserved

Mal EngineerVol. 231 No. 3 Oct1Nov 1977

advanced communicationsCommunication technology: an overview

Whither telecommunications?Diversified cost-effective satellite service for the 80s

editoral inputTechnical currency-it's money in the bank

advanced communicationsRCA Globcom's role as a carrierDigital processing of music for satellite communication

engineer and the corporationEngineering Information Survey results

advanced communicationsCommunication multiplexingMilitary communications-review and surveyComputer optimization produces a high -efficiency4-GHz MESFET linear amplifierReceiver voting extends two -way -radio range

Managing RCA Globcom's communication networkthrough automation

general interestComputerized inventory management at RCA RecordsBi-MOS technology produces a universal op amp

on the job/off the jobA single -wire alarm system using theCOSMAC microtutor

departmentsDates and Deadlines

Pen and Podium

Patents

News and Highlights

Communication technology: an overviewThe geostationary satellite provided the same kind ofquantum jump in communications capacity that Marconi'swireless did. Despite the added capacity with satellitesystems, new bottlenecks have developed.

K. H. Powers

Since the inauguration of electricalcommunication by Samuel F.B. Morsein the 1840s, telecommunication hasexperienced steady dynamic growthand its history has been characterizedby a continual race between the re-quirements for communication capaci-ty and new technological develop-ments. Since Morse's telegraph, themost significant milestones in thedevelopment of communication havebeen: Bell's invention of the telephonein 1985; Marconi's exploitation ofwireless telegraphy in 1900; DeForest'sinvention of the electronic amplifier in1908; Shockley's invention of thetransistor in 1948; and the launching ofthe first geostationary satellite in 1964.Each of these milestones has increasedthe capacity for world communi-cations. Of all of these milestones,however, I would select two-Marconi's wireless and the geosta-tionary satellite-as representing realquantum jumps in the potential com-munication capacity.

Marconi's development freed the worldfrom cable -connected installations,and at the same time, opened up thespectrum available for long-distancecommunications to about 30 MHz. Bythe same token, the satellite has freedus from line -of -sight limitations in thevast spectrum above 30 MHz.

Keeping up withthe growth rateThe growth of worldwide telecom-munications over the past hundredyears has been dynamic, yet very stable(Fig. 1). For the past 50 years or more,the telephone industry has been able topredict quite precisely (for five to tenyears out) the total system capacity

Reprint RE -23-3-2Final manuscript received October 13, 1977.

that would be required to service itstelephone customers. To meet the high rateof growth without utter chaos, telephoneengineers have been continuously develop-ing new switching techniques and newtransmission systems to use the existingtelephone plant more effectively.

On an international basis, the early growth inoverseas communications was provided firstby submarine cables and later by high -frequency radio. This met the needs from

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1B

100M

10M1860 188 0 1900 1920 1940 1960 1980

YEAR

BOOK VALUEU.S. COMMON CARRIERS

DOMESTIC PLANT(CURRENT DOLLARS)

Fig. 1Investment in communications has grown at acompound rate of 9.5% over the past century, ascompared with only 5.3% for the GNP.

4

Fig. 2There are only a finite number of slots available for geostationarycommunications satellites operating at the same frequency. Earth -station antenna beamwidth is the limiting factor. Presently,however, there is still unused space capacity, but a connectionbottleneck on the ground.

the early 1900s up to about the second World War, at whichtime the high -frequency radio spectrum became too con-gested. New submarine cables using extensive multiplexingwere then accelerated into service and have essentiallytaken care of the increasing demand for capacity untilrecent years. Much development has gone into increasingthe cables' bandwidth, which is relatively narrow. Althoughsubmarine cables are still being installed every year, most ofthe growth in international communications is taking placevia satellites.

Since the launch of Sputnik in 1957 and the development ofthe geostationary satellite Syncom in the early 1960s, theIntelsat series of satellites has produced since 1965 fourgenerations of geostationary satellites, placed in orbit overthe Atlantic, Pacific, and Indian Oceans. More than twentysatellites have been launched in the Intelsat series and thesystem now serves a ground configuration of over 120 earthstations throughout the world. In addition, domestic com-munication satellites have been launched by the SovietUnion, Canada, a European consortium (ESRO), and theUnited States. The total capacity of communicationsatellites in orbit today now exceeds that of all thetransoceanic cables that have been installed.

The backhaul bottleneckWith all this new capacity in orbit, one would think thattechnology had finally caught up with demand and thatfuture growth can be accommodated by simply launchingnew satellites and shifting to new higher -frequency bands.The number of geostationsary satellites that can share agiven frequency band is limited, however, by the beamwidthof the earth -station antennas (Fig. 2). The domestic systemscurrently in operation are assigned orbital slots at a nominal4° separation. Although empty orbital slots and unusedfrequency bands are currently available, the bottleneck incapacity has unfortunately just shifted back to the ground.Because satellite and terrestrial services share the 4/6-GHzbands, the gateway earth stations of the major populationcenters are customarily sited in quiet, shielded locations

Kerns Powers has been Staff Vice Presidentfor Communications Research at RCALaboratories since June 1977. He hadpreviously been Director of the Com-munications Research Laboratory theresince 1966. He has served on severalgovernment committees concerned withsatellite and terrestrial communications,and also holds six patents.Contact him at:RCA LaboratoriesPrinceton, N.J.Ext. 2746

several miles from their major customers in the city centers.These earth stations are then connected to the downtowncentral office by microwave backhaul, where line -of -sightlimitations and frequency congestion are again en-countered. Indeed, many of the gateway backhauls havealready reached their limits in frequency availability and theexisting installations cannot use all of the space -segmentcapacity available.

Even if optical links or some other magical solution to thebackhaul problem were suddenly found, a bottleneck wouldstill exist in the local loops that connect the subscribers withthe central office. Fiber optics promises relief in thissituation, but much development remains to be done. Themost promising near -term solution is in using satellitesoperating at 12/14 GHz, where the exclusive frequencyallocation and the shorter wavelengths will permit the use ofsmall earth stations located on customer premises, thuseliminating both the backhaul and the local loops.

Technology trends insatellite communicationsThe earliest Intelsat earth -station antennas had large dishesup to a hundred feet in diameter and employedcryogenically -cooled masers and parametric amplifierswith noise temperatures of 15-20°K to detect the weak

5

signals from the early low -powered satellites. (The Intelsat5 -watt transponder with earth -coverage beam provided anEIRP* of 22 dBW.)

The domestic satellite systems have been tailored after amore -recent higher -power generation of satellites (regionalbeams, EIRP = 32 dBW) and use a somewhat smaller earth -station antenna, typically 10 to 13 meters in diameter. Thetrend has also been toward lower -cost thermoelectrically -cooled parametric amplifiers at noise temperatures of 40 to100° K.

Although the cost-effectiveness of satellite transmissionhas been shown to be better than that for a terrestrialmicrowave circuit at distances greater than about 1000miles, one of the most significant attributes of thegeostationary satellite is its ability to communicatesimultaneously to multiple points on the earth's surface. Wehave therefore seen an increased use of satellites in thebroadcasting service, particularly television. This applica-tion has been accompanied by a trend toward even smallerreceive -only earth stations, with 41/2- to 6 -meter earth -station antennas for cable television operators becomingtypical. Fig. 3 shows a typical small receive -only earth

'EIRP stands for effective isotropic radiated power, which is the rt power multiplied by theantenna gain.

Fig. 3Smaller earth stations are replacing the earlier 30-m- and 10 -m -diameter dishes. This 5-m-dia receive -only station, located on theroof of an RCA Laboratories building in Princeton, N.J., is used forexperiments with RCA Satcom satellites. The RCA engineers in thephoto are Lewis Stetz (left) and Joseph Zenel.

100 K

10K

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NOISE TEMPERATURE1000°

Fig. 4Low -noise amplifiers for earth stations are decreasing in cost. Thetrend is for less sensitivity at the receiver at lower cost, but morepower at the satellite.

station. The low -noise amplifiers are also giving way to evenlower -cost FET transistor amplifiers with equivalent noisetemperatures down to 120° K. Fig. 4 shows the cost trend -line of low -noise amplifiers.

As the next generation of shuttle -launched satellites at12/14 GHz comes into service, we will see a continuation ofthe trend toward more EIRP in space and a larger number ofsmaller earth stations in the ground segment.

EIRP might be increased by either increasing the satellite'soutput power or by employing spot beams with on -boardbeam switching. Both these solutions involve tradeoffs. Anincrease in power output will increase the payload weightand, thus, will limit the number of transponder channels.The Canadian/U.S. Communication Technology Satellite,for example, carries a 200-W TWTA, but has only one suchtransponder; the RCA Satcom, on the other hand, uses 5-WTWTAs, but has 24 such transponders.

Beam -switching satellites would concentrate the outputpower into regional beams that are switched to the differentearth stations in accordance with the traffic. This mode ofoperation is more suited to point-to-point communicationsthan to the nationwide coverage that is now common withsatellite systems.

Presently, communications satellites consist of a relativelyunsophisticated communications package inside a highlysophisticated bus. This situation is changing, however, andthe communication systems in future satellites will becapable of doing much more than simply rebroadcastingwhat they receive.

In general terms, anything the satellite can do to sort andidentify message segments will make the ground equip-ment less complex and less costly. It might be cheaper toput the signal -processing equipment in one location-thesatellite-than in all the ground locations. Since timedivision multiple access (TDMA) is now a reality for spacecommunication (to be incorporated in the SBS and TDRSS

6

satellites in 1979), there will probably be a trend away fromthe "microwave repeater" satellite of today toward more on-board signal processing, with packet -switching protocolsdone in the satellite.

Developments in multiplexing

As technologists work to develop new media and devicesfor increasing communication capacity, communicationengineers are working equally hard to develop new techni-ques to make maximum use of the capacity available. Onetechnique is multiplexing, in which several channels ofcommunication are combined into a single signal fortransmission over a single circuit. This has been anecessary development to provide the engineers with theflexibility to match the communication signals to betransmitted with the bandwidth of the circuits available. In asense, time -division multiplex preceded frequency -divisionmultiplex as messages were transmitted over telegraphwires in a time -division manner, except that the time -division blocks consisted of complete messages.Frequency -division multiplexing was first developed forcarrier systems in the telephone industry and has seenextensive use in microwave systems. The more modernversion of time -division multiplex, which interleavessamples of several messages simultaneously, had to awaitrefined digital techniques and is a more recent develop-ment. A third type of multiplex, sometimes referred to ascode -division multiplex, is a new concept that uses complexwideband orthogonal signals to simultaneously multiplexmany channels in the same frequency band while overlap-ping in time. Code -division multiplex has not seen extensivedevelopment as yet.

Bandwidth compression techniques

Another major area of communication techniques develop-ment has been bandwidth compression, which is aimed atusing the spectrum more efficiently. Single-sidebandmodulation was one of the earliest of these techniques,whereby voice channels could be multiplexed in a carriersystem in approximately one-half the bandwidth that wouldbe required if double-sideband amplitude modulation wereused. The use of vestigial sideband in television transmis-sion is another example of a move in this direction. Moreimpressive, however, is the NTSC color tv system, whichuses a time -interlaced, frequency -interleaved subcarrier tomultiplex the chrominance information in the samebandwidth as the luminance.

The more sophisticated bandwidth compression ideas,born out of Shannon's information theory, wherein theinherent statistical redundancy in the signals is used toreduce the required bandwidth for transmission, have had aslow history of development because of the complexity ofterminal equipment that would be required to use thesetechniques effectively. Bandwidth compression of speechsignals has achieved large factors in the development ofvocoders with terminal equipment so complex that theirapplication has been limited to the military, where theadditional requirement of encryption has justified the highcost. However, in the past ten years, the technologists have

come to the rescue again with the development of large-scale integrated circuits for which the large storage and thevery complex signal -processing algorithms can be im-plemented without undue cost and size. Recently therequirement for privacy in mobile radios has led to theintroduction of an integrated continuously variable slopedelta (CVSD) modulation chip and a companion keygenerator chip in commercial mobile service. Thistechnology, with perhaps a linear predictive coding techni-que, should quickly find its way into microwave and satellitevoice circuits.

Bandwidth reduction of television has been the subject ofresearch for over 20 years, yet only recently has it beenachieved in commercially available equipment. Here ex-tensive new digital technology at high logic speeds isrequired, but the cost of this terminal equipment is still toohigh to permit extensive use, and in most applications theterminal costs exceed the cost of the bandwidth they save.Thus digital television must still await the large -volumeapplication that will justify the development of a high-speedintegrated A -to -D converter, a low-cost digital frame store,and a high-speed data -compression processor.

ConclusionMany trends are clearly evident. Communication satellitesare still in their infancy and their communication payloadsare currently little more sophisticated than a microwaverepeater. In future system generations we can expect to seemore power and complexity in orbit and further prolifera-tion of smaller lower -cost earth stations. The space shuttle,which will be operational by 1980, will reduce launchingcosts and permit heavier payloads. Extensive use of beamswitching will permit higher EIRP for the same payloadweight. On -board signal processing and storage will permitmessage switching in orbit, further simplifying the earthterminals. Indeed, packet -switching protocols and TDMAare just around the corner.

New communication technologies and devices will con-tinue to reduce costs and permit higher degrees of com-plexity. LSI and microprocessors are here, CODs and SAWdevices not far behind. Solid-state microwave devices willultimately replace TWTs and will continue to provide lower -cost low -noise amplifiers. There is still a clear trend towarddigital transmission for voice and video as well as data,although this trend has lagged behind predictions for thirtyyears. Fiber optics seems to have leap -frogged millimeterwaveguides and will no doubt find application in underseacables as well as in terrestrial trunks and local loops.

The race between technology and demand in telecom-munication has been evident for over a century, with eachleading the other at the same time in different segments ofthe business. We have a tortoise -and -hare phenomenon,with economics serving the role as the pacemaker. Asdemand exceeds the technology supply, a communicationbottleneck develops, whereas in the opposite case, a lack ofinvestment capital prevents excessive surplus capacity.Undoubtedly, the dynamic growth pattern we have seen willcontinue. One big question remains: what will be the nextmajor milestone?

7

automatic vehicle location automatic toll collection

Whither telecommunications?

H. Staras

radio lock

Telecommunications is growing by expanding its traditionalmarkets and branching out into new ones. How many of thisarticle's predictions will be realities twenty years from now?

The recent explosion in CB radio marks still anotherradio communications

since the early days of a.m. transmission. Even if thisparticular phenomenon turns out to be only a fad ratherthan the beginning of a major new radio communicationbusiness, one thing is sure-radio communications con-tinues to grow rapidly, and solid-state technology con-tinues to grow with it to make equipment more reliable, lessexpensive, and capable of operating at ever -higher fre-quencies. This last requirement is a must if radio com-munication is to continue to grow, since the lower frequen-cy bands are very crowded, and conflict between differentuser groups is already evident.

With that as a background, the following is an attempt toidentify some new radio communication systems that maybecome a reality during the remaining years of this century

Citizen's Band

Call for help on your pocket -sized "urban distress" CS.

CB radio "took off" during the oil crisis of 1973. Theconventional explanation relates to the truckers' attempt tocircumvent the newly -imposed 55-mi/h speed limit bynotifying each other where and when the police were. Bynow, there is evidence that that feature is much lessprominent than it once was, and that CB is frequently usedfor such desirable ends as notifying the police or healthauthorities about highway accidents or criminal activity,although just socializing seems to be its most common use.Some hotel/motel chains reportedly are considering im-plementing CB at their different locations to accept reser-

vations from motorists and to relay information abouthighway accidents and criminal activity to the appropriateauthorities. Extrapolating this trend, portable and evenpocket -sized, short-range CB radios may be used at higherfrequencies in urban environments to call for help in case offire, heart attack, or mugging, for example. In this connec-tion, there is some evidence that radio waves at 900 MHzand higher tend to propagate down city streets as in aslightly lossy waveguide. If further data pin down thepropagation characteristics more quantitatively andidentify the preferred frequencies, then a small array ofelectronic signposts emplaced in city streets may be used tolocate the source of the call for help.

Automatic vehicle locationElectronic signposts may be used to track vehicles.

The efficiency of operation of a fleet of land vehiclesprobably could be increased if management couldautomatically and continuously monitor the disposition ofthe vehicles throughout the service area. This holds forbuses, police cars, taxis, and commercial delivery vehicles.Several organizations have done a modest amount of worktoward developing an automatic vehicle location andtracking system. For fixed -route systems (e.g., buses), it'salmost certain that the most effective way of implementingsuch a system would be with the aid of a limited number ofelectronic signposts deployed along the bus routes coupledwith interpolation between signposts from the odometerreadings of the vehicle. The signposts communicate withthe vehicle by means of short-range radio signals. Thevehicles, upon interrogation, relay to the control center the

8

expanded satellite communications earth stations for long -haul trucking

signpost identification number, the vehicle's own identifica-tion number, and the accumulated distance since passingthe signpost. This permits the control center to ascertainthe location of all vehicles and their adherence to schedule,and then provide specific information to the dispatchers forappropriate action.

For random -route vehicles, the problem is a good deal morecomplicated. Experimental systems using phase -ranging,pulse -ranging, electronic signposts, and dead -reckoninghave been tested. One of the more recent ones involves adead -reckoning system that uses relatively crude but low-cost odometers and turn sensors in the vehicle. Thevehicles transmit digital radio signals carrying elapseddistance and turn angles since the prior communication to acontrol center, which has the city streets mapped into acomputer memory. Even if these estimates are fairly poor,the control center can identify the location of the vehiclequite precisely (within 100 feet or so) because it uses themap of the city to define the permissible motion of thevehicle and so can correct the inaccurate (or missed)information arriving from the vehicle. The U.S. Departmentof Transportation has recently undertaken a pilot programin Los Angeles to evaluate the performance characteristicsof a vehicle -location system that can track randomlymoving vehicles. In time, a preferred system among all thecompeting ones is likely to emerge.

Electronic vehicle identificationThe electronic license plate might be the microwave analog tosupermarket optical checkout systems.

In these systems, a "label" is attached to the vehicle. Aninterrogator, which may be imbedded in the roadway,mounted at roadside, or carried in another vehicle, is usedto interrogate the "label," which responds with a codedidentifying message. Three broad types of these systemshave been tested over the years. First are the opticalsystems, in which the labels have printed bars of differentwidths and spacings and the interrogator is a light sourcethat scans across the labels. A second system uses a low -frequency loop on the underside of the vehicle and another

electronic business mail

low -frequency loop buried in the roadway. The loop in theroadway induces a voltage in the vehicle -borne loop, whichthen retransmits a coded message containing its identifica-tion. The third type is the microwave label, which uses a flat,printed -circuit antenna and a coded digital message in theform of shift register with external hard -wired connectionsthat control the code circulating through it. The label doesnot radiate until it is irradiated by a cw transmission at thedesignated microwave frequency. When it is so irradiated,the label reflects an amplitude- or phase -modulatedmicrowave signal.

The advantages and disadvantages of these types of labelsdepend on the system performance characteristics desired.At a supermarket check-out counter, the optical scansystem is preferred. But there are interesting possibilitiesfor the others, too. The microwave label, for example, canbe the basis for an electronic license plate that can be "read"by an interrogator even while the vehicle is moving at highspeed. This can provide a basic element in an automatictoll -collection system on toll roads and bridges, anautomatic check -in system for rental vehicles, or even aradio -controlled lock.

The microwave lock system would use no keyhole or othermechanism that could be tampered with from the outside,but would instead emit a weak, very -short-range (feet) cwmicrowave signal. When the correct "key," in the form of themicrowave label described earlier, is dangled in the generalarea of the radio lock, the radio lock would detect anddecode the modulated signal reradiated by the "key" andspring the lock open. Experimental models of such a label,3" x 6" x 1/8", have been fabricated; even smaller ones arepossible in time. Such a radio lock has the intriguingpossibility of making door -opening more convenient (nofumbling with keys in the dark or when carrying packages)and more secure (physical access to the lock is not possiblefrom the outside).

This paper was originally presented at the National Telecommunications Conf,, Dallas.Tex., in November 1976.Reprint RE -23-3-11

9

Satellite communication systems

Both operating frequencies and the number of communicationcircuits are increasing.

The radio systems described earlier are a bit "iffy," althoughsome of them are almost certain to come to fruition in thenext two decades. Satellite communication systems, on theother hand, are already here to stay. They are establishedand continue to grow rapidly. The largest satellite com-munication system is Intelsat; a look at its growthprojection into the 1990s indicates the expected growth insatellite communications. There are presently about 18,000telephone circuits in the Intelsat system, but one scenariopredicts about 90,000 circuits in 1985 and 300,000circuits less than 10 years later. When this growth is coupledwith the growth in domestic satellite systems in Canada andthe United States, and shortly in Brazil, Indonesia, Japan,and possibly Iran, it becomes very clear that a major newcommunication technique has been born. Present com-mercial usage is predominantly in the 4/6-GHz band, butSatellite Business Systems, Inc. has announced plans for acommercial system at 12/14 GHz by 1980, and experimentalsystems are being evaluated in 18/30-GHz band. There is 1GHz of bandwidth allocated in the 4/6-GHz band, another 1GHz in the 12/14-GHz band, and 5 GHz of bandwidth in the18/30-GHz band. Although the United States and Canadahave been the leaders in this technology to date, theEuropeans and Japanese are beginning to make significantprogress. Commercial communications satellites (except inRussia) all use geostationary orbits. Over the Westernhemisphere, a proliferation of satellite systems in the pastseveral years has already created a problem with orbitalcrowding.

By and large, the function of a satellite communicationsystem is to supplement microwave and cable systemstransmitting telephone, television, and data signals overlong distances. However, there are two situations in whichthe satellite system becomes the most cost-effective. Oneoccurs when broadcast -mode transmission is required. Inthis case, the same signal or message is transmitted to manydifferent locations. The improved cost-effectiveness in thissituation arises because cable and microwave systems areessentially point-to-point, while a satellite system operatesnaturally in a broadcast mode.

An obvious example is tv networking. A major reason why tvnetworking via satellite has not yet been implemented on asignificant scale is lack of a "track record" on the part ofdomestic communication satellite operators, whereasAT&T is a known quantity to the broadcasters. But HomeBox Office, a distributor of pay-tv programming to cableoperators, and the Public Broadcasting System have madefirm commitments to distribute their programs via satellite.In fact, Home Box Office is already operating through RCASatcom.

The other situation in which a satellite system has anobvious advantage occurs when the population centers thatrequire communication are separated by large distancesand hostile intervening terrain makes cable or microwave

systems very expensive to install and maintain. Inter-continental traffic is a case in point; hence, the value of theIntelsat system. Alaska, Canada's Northwest Territories,Brazil, Iran, and several other such regions are interested intheir own domestic satellite systems for precisely thisreason.

In the remainder of this paper, attention will be limited totwo specific communication systems that have not gottenas much attention as others. One involves radio com-munication between over -the road, long-distance truckersand their home bases; the other is the electronic mailsystem.

Long-distance truck communications

Will small earth stations make satellite communication possible forlong-distance trucking?

Police cars, taxis, buses, and delivery vehicles startedoperating without mobile radio and developed effectiveoperating disciplines without it. However, mobile radio hasclearly helped increase their efficiency of operation to thepoint that it is now probably more common than not forthese classes of vehicles to have mobile radio. By the sametoken, over -the -road trucks and buses presently operatesatisfactorily without mobile radio-they have establishedan operating discipline that permits them to operate withoutit. However, satellite technology appears capable ofproviding a cost-effective mode of long-range communica-tion for these vehicles before the end of this century.Satellite communication systems have been designed toprovide long-range two-way communication with aircraft(Aerosat) and ships at sea (Marisat and Marots). These tendto be quite expensive. With Aerosat, aircraft must have anantenna that is essentially omni-directional and, therefore,low -gain. This, in turn, requires the satellite to radiate agreat deal of power in a narrow bandwidth. The narrowbandwidth, in turn, limits the amount of traffic that can becarried. In effect, this adds up to a high cost per voice orteletype channel. In the case of Marisat, the high cost comesfrom requiring a stable antenna platform on the ship, even invery high seas.

With land vehicles, these problems are much less seriousand the cost can become quite modest if one operationalconstraint is acceptable; i.e., the land vehicle should stop,pull over to the side of the road, and manually point a 11/2- or2 -foot dish, say, toward the satellite. A pilot tone from thesatellite could aid this procedure. When the base station istrying to reach the mobile user, a narrowband digital signalcould alert the vehicle to stop and receive the call.Assuming this constraint, a long-range telephone orteletype link could be established from the land vehicle to itshome base a thousand or more miles away. A roughcalculation (operation at L-band/S-band assumed)suggests that a truck or bus would require about $3000 ofvehicle radio equipment, and the rental charge for the use ofone satellite voice channel would be about $50/month. Themain difficulty in bringing such a system into being is nottechnology, but rather the nature of the business environ-ment. A truck or bus company cannot introduce such a

10

system on its own-a third party must invest the substantialamount of money necessary to place the satellite relaychannel in orbit. But there may come a time when acommunications satellite operator will see fit to add an L-band/S-band transponder for use by over -the -roadvehicles.

Electronic mail system

If the Postal Service doesn't implement electronic mail in the nextdecade or so, then private communication companies will.

There is just too much business mail (more particularly,financial -transaction mail and computer -generated data)not to recognize the value of telecommunications for itsdistribution. This will become even more pronounced whenword-processing machines replace typewriters almostcompletely. By then, business mail will automatically be in aformat eminently suited for transmission by telecom-munications. But to put the whole question of the electronicmail system (EMS) into perspective, it should be recognizedthat communications will probably account for less than 5%of the capital costs of the entire system. Input/outputterminals and store -and -forward facilities will account forthe lion's share of the costs associated with this new system.Nevertheless, telecommunications, and satellite com-munications, in particular, will be the vital new highway toreplace or, at least, complement trucks, trains, and planesfor mail service in the future. This trend will no doubt beaccentuated by the ever-increasing cost of, and pressure toconserve, fuel.

Note, though, that correspondence mail, especially of thesocial type, may not be amenable to handling by EMS for along time to come. However, business mail, in the form ofadvertising and form letters that are sent to many differentaddressees, is particularly cost-effective for EMS andshould be sufficient economic justification. But evenregular business mail, which is characteristically short andto the point, and which comes with preprinted letterheadsor on preprinted forms, is also quite cost-effective. In thisconnection it should be mentioned that the off -hourtransmission of nationwide newspapers and journals forprinting and distribution in many different regions of thecountry also appears to be quite cost-effective and somesuch systems are being tried out now outside the purview ofthe U.S. Postal Service. It is perhaps worth special note thatbusiness mail, particularly of the financial variety, requires avery low probability of error. Satellite communication linksappear to have characteristics that are the closest ap-proximation yet discovered to an ideal white gaussian noisechannel, so the likelihood that they will meet the low errorrates required for financial transactions appears very good.

Conclusion

This paper has outlined a potpourri of communicationssystems that are likely to see the light of day before thiscentury comes to a close. The reader is requested toremember those predictions made here that do materialize,and to forget those that fail to do so.

Harold Staras has had almost 30 years of professional experience(23 of them with RCA) in research and development, primarily inareas relating to propagation, communication, and radar systems.He is presently involved in satellite communication studies sup-porting RCA's communication satellite business. These studieshave included the effect of rain on depolarization of signals onsatellite links at 4/6 GHz, the role of companders in increasingtraffic capacity on FDM/FM carriers, and new methods for com-batting rain fading at 12/14 GHz.Contact him at:Communications Research LaboratoryRCA LaboratoriesPrinceton, N.J.Ext. 2731

Diversified, cost-effective satellite servicefor the 80sJ.E. Keiglerl D.S. Bond The first generation of satellite communications systems for

North America will mature by 1980. What's in store for thenext generation?

After a slow beginning, domestic communication -satelliteservice in North America is maturing rapidly as an integralcomponent of the total continental communication. TelesatCanada was the first to offer domestic service' with theirthree Anik satellites and widely distributed earth stationsand RCA began U.S. domestic service in 1973 by leasingtransponder channels on Anik II. Western Union soonfollowed with U.S. service via their two Westar satellites,'similar to Anik's 12 -channel design. RCA began operationswith its two 24 -channel RCA Satcom satellites in early1976,3 followed by AT&T's big Comstar satellite.4 The totalcapacity of these four 4/6-GHz systems already representsa significant fraction of the continent's long-distancecapacity.

Growth to maturityGrowth not only in satellite channel capacity, but in newfrequency bands, has begun with Telesat's recent contractfor a dual -band satellite to include 12/14-GHz channels inaddition to standard 4/6-GHz channels.' Likewise, SatelliteBusiness Systems is planning a 12/14-GHz satellite systemfor direct, digital customer service.' Both of these systemsare planned for service before 1980.

With the current North American domestic satellite com-munications systems thus reaching full maturity by the endof this decade, technical and economic planning for the1980s must encompass a broad spectrum of users. Otherthan the likely exception of the AT&T Comstar system,intended primarily for message trunking service as acomponent of AT&T's Long Lines Department, the NorthAmerican satellite systems of the 80s can be expected tocarry a variety of types of traffic and to employ a number oftypes of earth stations. Carriers will expand their private -line message and network tv distribution services, whilealso adding new services for smaller users.

Multi -purpose, diversified systems will spread the costs tomake service to small users possible without governmentsubsidy. Thin -route and single -channel -per -carrier servicewill dominate in the northern regions of Alaska and Canadaand perhaps even in parts of Mexico. The demand for low-cost, two-way tv for education and medicine has recentlyled to the formation of the Public Service Satellite Con-sortium. Direct user service for data transfer, with earthterminals on customer premises, is the raison d'etre of theSBS venture of Comsat, IBM, and Aetna. This proliferationof services, traffic volume, and number of earth terminals inthe 80s will require economies, not only in investment costs,but also in using the finite resources of orbit and spectrumspace.

Some present and future systemsThe authors are not endowed with any great gift ofprescience. The difficulties of forecasting events intelecommunications-just as in any field of science-arebrought out vividly in the writings of Arthur C. Clarke.' Themajor new discoveries, the shrewd application of knowntechnology, and changing economic and social factors allcontribute to unexpected applications for earth satellites.

However, if we recite a brief list of developments andapplications now being exploited or seriously considered,we may indicate some general direction for the early part ofthe 1980 decade. The list includes:

Communication common carriers, both international anddomestic, have been using satellites for heavy -routelong -haul telephone and record communication.Domestic systems especially are sure to proliferate in sizeand expand in traffic load.Television program transmission, point-to-point fornetwork program assembly and point-to-multipoint fordistribution to broadcast stations or broadband cablesystems, will become a major service in the years to come.Multipoint services are now expanding rapidly in Canadaand the U.S.Basic telecommunications to sparsely settled areas,isolated by geography or climate, are now being es-tablished. Their further expansion in the Canadian FarNorth and in Alaska will be discussed below. The servicesinclude public telephone, home radio and televisionreception, communication by video, voice, and data forhealth-care delivery, and communications for public andgovernmental functions. Instructional television isanother important application.Data transmission (and other transmissions) directlybetween earth terminals at users' locations are expectedto be employed by large business firms, governmentinstallations, and eventually by a multitude of smallercustomers. This can lead to the establishment of a radiomail system.Direct television broadcasting by satellite will initiallybegin to schools, community centers, villages, andmedical centers and clinics. Eventually, distribution tohomes is very likely in some countries. This use of directsatellite broadcasting for educational purposes in suchneedy countries as India was forecast some years ago"and was carried out to some degree by the NASA ATS-6satellite equipment in India.

Reprint RE -23-3-9A similar version of this paper was presented at the AIAA/CASI Communication SatelliteSystems Conf.. Montreal, Oue., April 5, 1976. This version was updated on October 20,1977.

12

Fig. 1"Thin -route" earth station at remote Eskimo community of Pang-nirtung, on Baffin Island in Canada's Northwest Territories.Unattended station, which provides two toll trunks to the outsideworld, is part of Telesat Canada system that began service in 1972.

Telesat Canada-the pioneerWhen Anik I was launched and put into service in late 1972,a new era in domestic telecommunications began. TelesatCanada's technical and economic innovations have hadprofound influence on all the subsequent systems that havebeen planned and put into service. One of the presentauthors was able to obtain an insight to the potential ofsatellite telecommunications in serving a sparse populationby visits to Telesat stations in the summer and autumn of1973.

At Frobisher, in the Northwest Territories, the "northerntelecommunications" (NTC) station provided multitrunktoll telephone service to the provinces and throughout theNorth American Integrated Network. It is also brought high -quality CBC television programs to the community. Pang-nirtung, a much smaller and predominantly Eskimo com-munity near the Arctic Circle on Baffin Island, uses a "thin -route" earth station to provide two toll telephone trunks tothe outside world from a small step-by-step office of BellCanada. The earth station, illustrated in Fig. 1, is un-attended. The quality of transmission and the inherentsimplicity and economy of service impressed the RCAvisitor tremendously and greatly influenced the current vastRCA program of telephone communications to rural Alaskaby earth satellite.

Telesat itself now has about 25 thin -route and larger earthstations for message traffic, and will add at least 10 more inthe next two years. Almost all are in the territories (north ofthe 60th parallel) or the northern part of the provinces.

Television -program distribution by remote tv-receive earthstations was considered highly important in Canada andbegan in the spring of 1973. Later that year Whitehorse,Yukon Territory was visted. That "remote television" sta-tion, which obtains network -quality tv from CBC's NorthernProgram, is unattended, but receives periodic maintenanceby CN Telecommunications. A trip was made toYellowknife, NWT, over a year later to learn about long-time

reliability of the remote tv earth stations. Substantially nooutages had occurred-a marvelous record, attesting to theinherent reliability of space communication systems andthe excellent engineering of the earth stations by Telesat. Atthe end of 1975, there were about 45 earth stations inCanada equipped for tv reception, including the two large"heavy -route" stations and the six "network tv" stations inthe provinces. Both the latter types are arranged for tvtransmission, and several more remote tv stations areplanned for the next two years.

Satellite telecommunications for AlaskaMany of the innovations of Telesat Canada are being put intopractice in Alaska.

RCA puchased the statewide long-distance telephonenetwork from the U.S. Air Force in 1970, and early in 1971became the sole long -lines carrier in the state. The AlaskaCommunications System then consisted of a number oftropospheric links, microwave relay circuits, miscellaneousother terrestrial facilities, and submarine cable. The systemwas configured principally for military traffic and wassuddenly becoming inadequate for the rapidly growingcommercial traffic to Alaskan cities. It served very few of thesmall bush communities.

Early expansion plans by RCA included satellite toll trunksfor high -traffic routes from the Anchorage, Fairbanks, andJuneau toll centers to the "lower 48" states. The success ofdomestic satellite systems in Canada for both heavy -trafficand thin -route applications showed clearly that most of theexpansion in rural areas and for interestate traffic should bebased on the use of satellite, rather than microwave ortropospheric, systems.

In the two-year period up to the end of 1975, seven 10 -meterearth stations of medium to high capacity were installed inAlaska by RCA. These included Lena Point (servingJuneau), Bethel, Nome, Prudhoe Bay, Valdez, Yakutat, andCordova.

The Alaska "Bush Program" began bringing limited telephoneservice by satellite to small communities in mid -1975.

A joint undertaking of the State of Alaska and RCA, theprogram is for small communities ranging in populationfrom 25 to several hundred. Twenty "small" (thin -route)stations were in service by mid -1976, and eighty more are tobe installed by the end of 1977. Each will initially providetwo circuits, one for public telephone use and the other for aprivate line or net circuit for the Native Health Aide in thecommunity. The installations are capable of later expansionas traffic warrants.

Each station uses a 4.5 -meter -diameter antenna and a low -noise rf amplifier (LNA) of about 200°K equivalenttemperature. The overall station G/T becomes about 19-20dB/°K, depending on antenna elevation angle. Single -carrier -per -channel equipment is used, with at least twomodulation methods possible.

Color -television reception capabilities have been added tomany of these thin -route stations. NTSC color standardsare employed and rf modulation is compatible with that inuse in the lower 48 states and Canada to permit reception of

13

14

Fig. 2Telemedicine by satellite experiments in Alaska began in 1974. The twoantenna dishes here link the lone nurse at the Alaska Area Native HealthService Clinic at Ft. Yukon with physicians at an Anchorage hospital.

direct network satellite feeds. This undertaking is beingsupported by the State of Alaska. Effective LNAtemperatures in the range of 120° K are planned for higher -quality reception at the EIRP values obtained with the RCASatcom satellite.

Telemedicine is now linking remote Alaskan communities withmedical centers.

Telemedicine is now the subject of extensive field tests inthe United States. Foremost among the experiments are therecent ones in Alaska using the NASA ATS-6 and the ATS-1satellites. The Alaska experiments, as well as those in thelower 48 states, include two telecommunication links:

Audio-Two-way telephone service, and, in Alaska,provision for telemetering patients' vital readings ortransmitting of health records.Two-way television-Between physician and nurse orbetween general -practitioner physician and specialist.

The telemedicine experiments conducted by the AlaskaArea Native Health Service in 1974-1974 were mostfavorable and point the way to the initial operational phaseof use of telemedicine for the Alaska Natives. One of theauthors became an instant sourdough by visiting Ft. Yukon,Alaska in January, 1975, immediately after the end of a-70° F cold spell that isolated the community for ten days.During that time the health care of the people was entirely inthe hands of the one nurse at the Native Clinic. Heretelemedicine demonstrated its worth in providing visualcontact with the physicians at the referral hospital inAnchorage. (See Figs. 2 and 3.)

Plans are now being implemented jointly by the AANHS andRCA to link the small regional hospital in Bethel and thelarge Anchorage facility by telemedicine. This involvessatellite transmission of full duplex video and voice betweenthe existing RCA earth stations at Bethel and Talkeetna.Many of us feel that current commercial communicationsatellites (like Anik, RCA Satcom, or Westar) and earthstations like those in Alaska offer telemedicine at vastlylower total cost than via an ATS-6 satellite.

Ultrafax radio mail serviceIn this proposed new satellite service for the 1980s, we shallnot use Alaska as the example, but rather treat the North

Fig. 3Telemedicine camera in the examing room at the Ft.Yukon clinic.

American market more broadly. In doing so, we areskipping over the application of high-speed digitaltransmission for a variety of well-known uses, e.g., traffic toand from computers for scientific and business datatransfer.

Thirty years ago RCA disclosed a method of radio mailtransmission called Ultrafax.9 Each frame of a tv signalwould transmit one page of copy in facsimile form. Atstandard scan rates, a tv channel could accommodate 30pages a second or about a million words a minute in analogform. Demonstrations were given in 1948 across the city ofWashington, D.C. to the Library of Congress using a 6-GHzmicrowave link. The expected transmission rates wereachieved. As an example, the entire book Gone with theWind was transmitted in slightly over two minutes. It wasrecorded on 16 -mm film and rapidly processed.

The art was not sufficiently advanced then to offer com-mercial success. With more recent advances, and under thestimulus of rapidly rising costs of physically moving mail,the opportunity is now being reconsidered by severalorganizations in the U.S.19 The wheel is being re -invented.The principal new tools are:

1) earth satellites for low-cost long -haul circuits;2) earth terminals for use on the premises of large users(post offices, large business firms, and governmentestablishments);3) broadband cable systems (like CATV) to providechannels to small users, eventually including individualhouseholds;4) digital facsimile transmission by PCM for efficientchannel use and good half -tone rendition; and5) improved high-speed facsimile recorders using dryelectrophotography and laser and other light sources.

Spectrum and orbit crowdingBottlenecks are starting to form.

Benefitting from the prior experience of the Intelsat system,domestic carriers in service to date have exploited the 4/6-GHz band, which represented little technical risk. Thesefrequencies had demonstrated transmission characteristicsand well -developed hardware technology for spacecraftand earth stations. However, since this frequency band isshared with terrestrial microwave systems whose density is

greatest near metropolitan areas, frequency -coordinationrequirements compelled the typical earth station to belocated fifty or more miles from the urban area it serves.Hence a significant part of the cost of domestic satelliteservice to date is the terrestrial "tail" that connects the earthstations to the urban areas and distributes the signals to theusers.

As the number of domestic carriers, their satellites, andtheir earth stations operating in the 4/6-GHz band havesteadily grown, the proper utilization and allocation of thelimited spectrum and orbit space have become moreimportant. With its responsibility for frequency andlongitude assignments, the FCC, with support by NASA andcooperation of the Canadian Department of Com-munications, has continuously had to balance the con-flicting demands of more satellite "slots" with the desire forlower -cost earth stations using smaller antennas. Advancesin component technology for both the output power anddirected EIRP of the satellites and the low -noise amplifier ofthe earth station have made smaller ground antennastechnically feasible and attractive to some users, but thelarger beamwidth of small -diameter antennas limits thelongitude spacing of adjacent satellites.

Although the number of 4/6-GHz satellites planned forNorth American service by the four carriers now in thebusiness (AT&T, RCA, Telesat, and Western Union) isconsiderably less than the peak originally requested whenthe FCC opened its domestic file in 1970,11 there is stillconflict in the optimum central region of 105 to 125° Westlongitude. NASA's study12 has indicated that maximum useof the equatorial arc will require not only limiting theminimum earth -station diameter, but coordinating channelfrequencies and polarizations of adjacent satellites. Whilethese results conclude that a 1.5 -degree spacing of like -polarized spacecraft operating into 10 -meter antennas ispermissible from an interference criterion, the FCC has notto date allowed orbit assignments closer than five degrees.Firm policy on orbit, frequency, and polarizationassignments is unlikely to be established until the demandsand conflicts reach the crisis stage.

Several of the satellite communications carriers are taking theirown steps to use spectrum and orbit space more efficiently.

AT&T's Comstar and RCA Satcom have introduced cross -polarization techniques to double the number of standard35 -MHz transponders channels per satellite from 12 to 24within the allocated 500 -MHz bandwidth at 4/6 GHz. Notonly can other users be expected to eventually adopt dualpolarization for similar economic reasons, but the FCC mayeventually require it (in a single satellite or two collocatedsatellites) in order to use the equatorial arc serving NorthAmerica optimally.

Beam isolation is another technique for spectrum reuse that mayfind application for domestic service.

It is being introduced into the latest series of Intelsatsatellites, and is applicable where distinct geographicalareas have different traffic. Severe antenna sidelobe re-quirements must be attained to prevent inter -channelcrosstalk, but the advanced multiple -beam antennas beingdeveloped currently for the Department of Defense mayprovide a practical alternative to the brute -force approachof individual high -gain antennas. Limitations on areacoverage, connectivity, and flexibility of channel assign-

ment may pose restrictions on beam isolation for spectrumreuse even if new antenna developments make it technicallyfeasible. However, if these limitations are compatible with aparticular carrier's operations, beam isolation not only usesorbit/spectrum space more efficiently, but also providesmore effective power utilization because of the higherantenna gain of the smaller beams.

Satellite systems operating at higher frequencies have a number ofadvantages.

Telesat Canada has recently started its program foroperating at 12/14 GHz. In spite of the known susceptibilityto heavy rainfall attenuation, this higher band offers threesignificant advantages to the carriers. First and mostimportant, the band (11.7 - 12.2 MHz space -to -ground and14.0 - 14.5 MHz ground -to -space) is dedicated to satelliteservice, so frequency coordination for ground -antennasiting is greatly eased, and antennas can be located in urbanareas rather than 50 miles away. Second, with no fluxlimitations because of shared service, higher satellite EIRPcan be used, so customers can use smaller ground anten-nas. And third, 12/14-GHz satellite locations can be in-terspersed, or virtually collocated, with 4/6-GHz satellitesfor optimum North American coverage.

Now that advances in device technology, both for satellitereceivers and TWTAs, have made systems in this bandtechnically and economically feasible, both multiband anddedicated 12/14-GHz satellite systems will expand duringthe 80s as they become the most cost-effective forparticular types of users. No North American applicationsare yet committed, but the 12-GHz band is of course alsoallocated to direct broadcast satellite service. Three ex-perimental direct broadcast programs are being funded byCanada/U.S., Japan, and Germany. The Canada/U.S.(CTS) Satellite is now in orbit and experiments are beingconducted.

While spectrum reuse and multiple bands have eased thestrain on the availability of orbit/spectrum space, in-creasing traffic and demands in the 80s will give rise tostandardization for most efficient use of the space. Theoutstanding question is whether such standards will bevoluntarily adopted by the carriers and/or hardwaresuppliers, or imposed, either by regulation of the FCCand/or treaty via the WARC and ITU.

Satellite system costsCost-effectiveness is now paramount.

As the satellite communications industry expands, using allthe advances in earth -station, satellite, and launch -vehicletechnology that become available, the overriding necessityof cost effectiveness will govern the characteristics of eachelement of the system. Unbalanced systems, in whichoveremphasis on low cost of one system element results inextraordinary costs elsewhere, will not thrive, not even withgovernment participation. Although ATS-6 demonstratedthe technical feasibility of a high -gain, high-EIRPspacecraft, the government could completely underwritethe cost of more than 2000 ten -meter earth stationsoperating with a Delta -class spacecraft before reaching thecost of ATS-6.

Launch -vehicle choice affects payload and cost.

For practical planning purposes for operating serviceduring the early 80s, although the space shuttle is pending,

15

16

there are only three proven classes of launch vehicles forgeostationary satellites-the Delta, Atlas -Centaur, andTitan-which have costs approximately in the ratio of 1:2:4.Although their payload weights into final synchronous orbithave the same approximate ratio, and thus their costs perpound of payload in orbit are comparable, it may be neitheroptimal to employ larger satellites nor desirable to "put somany eggs (or dollars) in one basket" with regard to therisks of successful launch. Of these three launch vehicles,the Atlas -Centaur has been used the most for communica-tion satellites, nearly all for Intelsat. However, the Delta hasbeen the choice of three of the four North Americandomestic systems, because its lower investment was impor-tant to systems having uncommitted traffic load andrevenue. As spacecraft designs have become more efficientand the Delta's capability has increased with the 3914series, it has become the basis for numerous new systemplans abroad as well as in North America.

NASA's current plans are to replace all three of theseexpendable launch vehicles with the space shuttle by themid -1980s. Shuttle launch costs will be directlyproportional to the size and weight of the spacecraft,according to the announced pricing policy. Hence, thepreference for minimizing the spacecraft size and weight fora given communications capability will be as much as adriving force in system design in the shuttle era as it is nowwith expendable vehicles.

The type of spacecraft chosen will also affect cost.

Spacecraft size and cost are approximately proportional tothose of the respective launch vehicle. Despite the widevariations in spacecraft configurations and com-munications payloads, experience to date shows a closecorrelation between spacecraft weight and total cost perspacecraft, where the total cost includes both initialdevelopment and any applicable performance incentives.

As shown in Fig. 4 (derived from published data), thisrelationship for total spacecraft cost closely follows the firstpower of spacecraft mass. The cases of noticeable depar-ture from the linear relationship represent either efficientdesign (below the curve) or unusual development andcontracture! complexity (above the curve).

Trends in commercial, military, and foreign com-munications satellites confirm that maximum payloadweight and power capacity are provided by three -axisstabilized spacecraft designs as compared to the earliergenerations of dual -spin satellites with despun antennas.While the cost per kilogram of an -orbit mass adheres to therelationship of Fig. 4 the communications capacity perkilogram is significantly greater. For example, the channelcapacity and El RP per channel of RCA Satcom is equivalentto that of Intelsat IVA and double that of Anik. Hence, whilethe dollars per kilogram of all three are nearly equal, thecost per channel of the three -axis stabilized RCA Satcom isappreciably lower.

In addition to the initial spacecraft and launch -vehicle cost,of course, the reliability of each contribute to the life -cyclecost of the system. Launch -vehicle failures are more drasticwith the larger spacecraft. With comparable launch -failureprobabilities for the Delta and Atlas -Centaur, for example,there is a double incentive to achieve a satellite designcompatible with the lower -cost booster, since program costplanning must include launch failure(s) as well as the basic

0V)z

_1 H

Hz

0z

z

cnO 0(-)w>J 0

22

20

18

16

14

8

INTELSAT I VA (8)

INTELSAT IV (8)

ANIK 13)

MARISAT (31

DSCS-I I 16,

RCA SATCOM (31

INTELSAT 111(8)

200 300 400 500 600 700

INITIAL SYNCHRONOUS ORBIT MASS, KG

800

Fig. 4Total spacecraft cost is directly proportional to spacecraft mass.Note that RCA's Satcom satellites are cost-effective designs.

vehicle cost. Similarly, premature in -orbit demise of thesatellite increases the program costs for replacementsatellites plus another launch vehicle. To limit the possiblefinancial losses from either launch or in -orbit failures, thecarrier may elect insurance coverage, which is anothersignificant cost that must be factored into the total programcost considerations.

Earth -station costs are decreasing.

Earth -station costs are influenced greatly by: the amountand types of channelizing equipment; the number of rftransmitting and receiving channels; the type of modulationemployed; the figure of merit (G/T) and transmitter EIRPrequired for voice, television, digital, or other traffic; andother system factors. Thus, it is impossible to directlycompare the cost of a large Intelsat earth station with a thin -route installation having only one or two voice circuits.Inflation produces an additional cost bias. The prices ofbuildings, civil works, auxiliary power supplies, and anten-na de-icing equipment (in certain locations) are importantparts of system costs. In remote areas like rural Alaska, thefreight charges for equipment delivery, installation laborcosts, and transportation of field engineers and techniciansadd up to a disproportionate fraction of the total systemcost.

If we look next at thin -route telephone stations for the FarNorth in North America, we find a steady downward trend incost as field experience has been gained. Antenna dia-meters have decreased from about 8 meters to about 4meters, and certain redundancy has been removed. Ananalysis of the trade-off of antenna vs LNA performanceand costs indicates that for the less favorable sites, whereEIRP values may be 32-33 dBW, a reasonable range ofpreferred antenna sizes for tv is 5 to 6 meters.

Table ITV -circuit tariffs show cost advantage for satellite system. Local -loop charges are included, as are monthly station commercialchanges for the terrestrial carriers.

Table IIAudio -circuit tariffs also show cost advantage that satellite systemhas over terrestrial microwave systems.

FacilityTariffbasis

Approximate Costcost per hour ratio

RCA satelliteAT&T terrestrial

microwaveAT&T terrestrial

microwave

5 hours/day $ 30010 hours/day 690

Occasional usehourly basis

FacilityTariffbasis

Approximate Costcost per month ratio

RCA satellite2.3 (two-way)

AT&T terrestrial1850 6.2 microwave

(one-way)

1.0

Telesat Canada has developed an advanced design(Anikon), which can be air -transported as a single load in atwin -engine DeHavilland Otter aircraft and then erected ona prepared site, ready for operation in less than eight hours.With the costs of sending an installation crew to a remotesite, where living accommodations are nonexistent andwhere premium labor rates must be paid, the value of theAnikon design is clear.

With somewhat less advanced earth -station packagedesign, RCA is installing the 20 small bush earth stationsdescribed earlier, with two high -quality telephone circuits.The average station has a turn -key cost of less than $80-90thousand. This figure will probably decrease as productionquantities rise, as cheaper foundations in permafrost aredeveloped, and as operating and maintenance experiencegrows.

Diversified -service satellite systems

The competitive pressures in the 1980s can be expected toresult in the dominance of satellite systems that have thelowest cost per channel. Except for a few specializedcarriers who may operate continuously at virtually full load(e.g., AT&T) or with their particular traffic to a select groupof users (e.g., SBS digital business data), the competitiveNorth American systems of the 80s are likely to offerdiversified services to a wide range of users. Expanding onthe pattern being established by Telesat Canada and RCASatcom, service costs to all users, including small terminalswith only intermittent traffic, will be minimized by employ-ing satellite systems with the flexibility to operate with avariety of types of traffic and earth stations.

It should be noted that satellite systems will have to survivenot only the competition with one another, but also withterrestrial systems. The two cases below give side -by -sidecomparison of satellite and terrestrial costs in commercialservice for the tv and radio networks. The sources for thecomparisons are published tariffs on file with the FederalCommunications Commission early in 1976.

In one case, RCA has contracted to provide a televisioncircuit from Los Angeles to New York City for one of the U.S.networks. The service is required 5 hours every day and ison a long-term contract. Previously this service had beenprovided by AT&T at either an "occasional use" hourly rateor a ten -hour -per day rate. The satellite system's costadvantage is shown in Table I, which compares theterrestrial and satellite tariffs.

In the second case, RCA is furnishing a program -qualityaudio circuit via satellite to the same network for servicebetween New York City and Los Angeles. The audio band is

Monthly rate

Monthly rate

$ 2,400 1.0

16,800 7.0

from 50 to 8,000 Hz. The circuit was formerly supplied byterrestrial facilities of AT&T with the maximum audiofrequency actually limited to 5,000 Hz. The satellite circuit istwo-way at no additional charge, to allow for future needs.Table II shows the the comparative costs, which are again tothe satellite system's advantage.

We think that the comparisons made here carry a clearmessage about the economic superiority of long satellitecircuits.

References

1. Almond, J.; (Session Chairman), Telesat Systems, AIAA Papers 74-451, 452, 453, 454,and 455. AIAA 5th Communications Satellite Systems Conf., Los Angeles, Apr 23,1974.

2. Verma, S.N.; "U.S. domestic communication system using Westar satellies," WorldTelecommunication Forum, Geneva (Oct 7, 1975).

3. Napoli, J., and Christopher, J.; "RCA Satcom system." National TelecommunicationsConf., San Diego (Dec 3, 1974) and RCA Engineer, Vol. 22, No. 1 (Jun/Jul 1976).

4. Rusch, R.J.; "Comsat general domestic communications satellite," National Telecom-munications Conf., San Diego (Dec 3, 1974).

5. Thorpe, D.G.; "Evolution of the Telesat Canada system into the mid -1980s," AIAAPaper 76-220, AIAS/CASI 6th Communications Satellite Systems Conf., Montreal (Apr5, 1976).

6. "Applications of Satellite Business Systems for a domestic communications satellite,"filing before the FCC (Dec 1975).

7. Clarke, Arthur C.; Profile of the Future, 1962. Harper and Row, New York. (NoteChapter I, "Hazards of Prophecy.")

8. Bond, D.S.; "Performance characteristics of a system for direct television broad-casting from earth satellites," Intl. Conf. on Satellite Communications, London (Nov22, 1962).

9. Bond, D.S., and Duke, V.J.; "Ultrafax," RCA Review, Vol. 10 (Mar 1949) p. 99.

10. U.S. Patent 3,594,495; "Radio facsimile postal system" (Jul 20, 1971).11. Report and Order "Establishment of domestic communication satellite facilities by

non -governmental entities," FCC Docket No. 16495 (Mar 24. 1970).12. Freibaum, J., and Miller, J.E.; "NASA spectrum and orbit utilization studies for space

applications," AIAA Paper 74-434, 5th Communications Satellite Systems Conf., LosAngeles (Apr 22, 1974).

John Keigler (right) ledthe design team whosework culminated in thepresent RCA Satcomprogram and also led thegroup that developed andtested the Stabilite three -axis control system nowused on polar -orbitingand geosynchronoussatellites.Contact him at:Communication Satellite

SystemsAstro-ElectronicsPrinceton, N.J.Ext. 2848

Donald Bond, a retiredRCA engineer who is aconsultant to RCA, hasworked extensively in thefield of satellite com-munications.

17

editorialinput

Technical currency

it's money in the bank

Being "technically current" is very important to engineers.We all know it, and the Engineering Information Surveyresults in this issue prove it.

But exactly what does "technically current" mean...notacademically, but in a real -life practical sense to theworking engineer at RCA? It is really quite simple: If youare technically current, you are ready to carry out yourengineering assignments in today's highly competitiveenvironment! No more, no less. Put another way, you mustapply the latest, most cost-effective engineering tools toyour present assignment...and be knowledgeable enoughabout technology to work rapidly into a new product fieldshould your old one become obsolete.

Although the definition of "technically current" appearssimple, its implications for the practicing engineer are not.If you're a specialist and an authority in your field-and theproducts you support are among the best available-doesn't that prove you are technically current? Unfor-tunately, no. You may have started with the sharpestengineering tools, done creative work, and then, as yourproducts matured and their manufacture was simplified,your challenges diminished and your tools dulled. Nowyou may be rapidly moving towards becoming one of theworld's foremost experts on a product nobody wants,which hardly means being technically current!

The implication is that, to keep technically current, youmust overcome the very real obstacles and inertiapresented by your daily work assignments and directsufficient time and energy to the task of learning currenttechnology, gaining working knowledge of new engineer-ing tools and techniques as they emerge, and finding waysto use some of this newly gained knowledge.

To accomplish this, you must go beyond specialty;consider such questions as: How will the new technologyaffect my product? Will it produce a different kind ofproduct that will obsolete mine? Is is presenting newopportunities for me?

Is it possible to keep technically current in today'senvironment of enormous information growth? Evidently,yes. Look around RCA; you will see very many examples ofkey contributors who have made the transformation intoone or more new technologies that were completelyunknown at the time of the contributor's initial education.

And they have innovated new techniques and products ineach technology. Unfortunately, there are also too manyexamples of those who have not kept technically current,whose specialty is no longer useful, and who must leavethe engineering field-unable to compete. At this point, itmatters little whether the cause was negligence or badadvice-the engineer must face reality alone.

A substantial number of today's engineers were educatedin the era of electron tubes. These engineers subsequentlylearned about semiconductors, and participated in theobsolescence of their earlier products. They saw in-tegrated circuits of increasing complexity challenge dis-crete transistors and realized that digital technologywould tremendously influence electronics. Today, manyof these former tube "specialists" are enjoying thechallenges and opportunities of microprocessor -controlled product design.

What other profession has had such a task of continuinglearning and keeping technically current and the excite-ment of so many new breakthroughs? How could anengineer survive professionally in the ever-changingelectronic technology jungle without keeping technicallycurrent next year...and next!

To help you find out how technically current you are, theRCA Engineer is publishing a series of papers giving theresults of the Engineering Information Survey, beginningwith this issue. As you read these papers you can compareyourself with your peers at RCA and possibly discoversome effective ways to enhance your technical viability.Remember, it is never too late to improve.

Join and stay with those for whom engineering is anexciting, satisfying lifelong career.

-Hans Jenny

Hans Jenny has experience as a design engineer, engineeringleader and manager, and Chief Engineer and OperationsManager of RCA's solid-state microwave product line. Hispresent position of Manager, Technical Information Programs,for Corporate Engineering uses this background to assist RCAengineers in their and the Corporation's efforts to remain viableand competitive. If you have questions or recommendations onthis topic, please call Hans at PY-4251, Cherry Hill, or fromoutside RCA, 609-779-4251.

18

RCA Globcom's role as a carrier

RCA started out as an international communicationscorporation in 1919. RCA Globcom has taken that base andexpanded it to over 70 times its initial sales with a number ofinnovative services.

Overseas telecommunications has gone through a steadystream of evolutionary changes and we are now on thethreshold of further transformations. These are evolvingfrom new developments in technology, a growing marketfor data transmission, the multiplying need for com-munications services by business and government, andbasic revisions in Federal Communications Commissionpolicy. All of these factors will play significant roles inshaping the direction of international record com-munications in the future.

Over the past two decades, the industry has made signifi-cant strides in bringing modern, efficient, low-cost com-munications to the far corners of the earth, linking bothindustrialized and emerging nations. You can now reachalmost any place in the world by telegram, telex, or on aprivate line with little more difficulty than you can callacross town. In the face of spiraling costs, this expansionhas been done with improvements in the quality of serviceand reductions in the price of these services.

Perhaps the best way to dramatize the differences betweenrate reductions in international and domestic com-munications is to look at the ordinary domestic telegram,whose cost has risen by as much as tenfold since World WarII. By contrast, internationally, a full -rate message today tomost parts of the world costs the same and, in some cases,costs less than it did twenty-five years ago. Internationaltelex, which, at the outset of the 1970s, had a minimumcharge of nine dollars for three minutes, is now available fora minimum of two dollars for one minute.

How does RCA fit into this picture?For over half a century, RCA Global Communications, Inc.has been one of the world's leading overseas commoncarriers, supplying a wide spectrum of services linking thecontinental United States with a globe -spanning network oftelecommunications facilities.

Today, RCA Globcom still performs the basic internationalcommunications that was the original function of RCAwhen it was formed and acquired the Marconi WirelessTelegraph Company in 1919. RCA inaugurated commercialoverseas radio communications on March 1, 1920 withmessages sent between New York and London. In its firstfull year of operation, RCA's revenues were $2 million. Incontrast, RCA Globcom's 1976 sales were $143.8 millionand RCA Corporation reported record sales of $5.4 billion.

J.C. Hepburn

Communications facilitiesRCA Globcom maintains the world's largest internationalnetwork of voice/record circuits,* serving more people(comercial users, government agencies, the news media,and the public) in more places than any of the otheroverseas carriers. Globcom employs high -capacity trans-oceanic cables, terrestrial microwave systems, satellitesystems, and high -frequency radio circuits in a network ofmore than 2500 telegraph and voice frequency channelswhich are growing in number each year.

We have invested about $300 million in plant and facilitiesand employ over 2500 people. The company operatescircuits jointly with our correspondents on the globalIntelsat commercial communications satellite system and ispart owner of the seven U.S. earth stations for that system.RCA Globcom installed, and now maintains and operates,the United States earth station in Guam. To meet projectedworldwide communications growth, we are investing ap-proximately $7.7 million in the next few years to expand andextend cable circuit facilities. RCA Globcom has a $5million investment in TAT -6, the world's highest -capacity,completely transistorized submarine cable, which stretchesfrom Rhode Island to France. The first of RCA's 115 circuitsin this newest transatlantic cable was activated in August1976, connecting the United States with Germany. By theend of 1977, approximately 70 TAT -6 circuits should beactivated to points throughout Europe and beyond. Thebalance of the circuits will go into service as soon asadditional capacity is required.

The company is also planning to invest in the proposedCaribbean Cable System, which will link the U.S. mainlandwith Puerto Rico, the Virgin Islands, Brazil, Venezuela andneighboring Latin American countries. The new cable isexpected to be operational by 1978 and will provide the firstdirect all -cable route to Brazil.

RCA Globcom has historically been the leading U.S. carrierserving points in the Pacific. To maintain this position, wehave invested approximately $20 million in TRANSPAC II.This cable system, completed in late 1975, links the U.S.mainland and Japan via Hawaii and Guam and providesservice between the U.S. and other Asian countries. Ex-isting and planned cables beyond Japan will connect

'As used in this article, the term "voice/record" includes telegram, telex, leased telegraphchannels, alternate and simulanteous voice/data channels, data, and facsimile transmis-sion.

19

Fig. 2Automatic dial -in (ADI) computer reduces processing time forinternational telegrams, also provides instant billing information.

Taiwan, Hong Kong, the Philippines, Korea, and thePeople's Republic of China.

RCA Globcom's customersRCA customers consist of a diverse roster of small and largecompanies and individuals who require overseasvoice/record communications services. These includebanks and brokerage companies, oil companies, shippingand freight forwarders, trading companies, importers andexporters, and the automobile, steel, aluminum, copper,rubber, electronics, clothing, and shoe industries. Com-munications users also consist of brokers in the wheat,cotton, corn, cocoa, and coffee commodity markets, air-lines, transportation and insurance companies, and theservice industries, such as auto rental, hotels, and travelagents. To these must be added foundations, universities,the world's consulates, state and U.S. Governmentagencies, news services, and the general public.

Fig 1Automatic retrieval computer (ARC) is an example of telegram -facility automation. Telegrams for overseas destinations must fitinto a proper international format; the ARC automatically removesmessages from the Computer Telegram System (CTS) that are notin the correct format and displays them on this CRT monitor.Operators make needed corrections and then route the telegramsback to the CTS.

Photo credit: Ai Garratt

CompetitorsWhile RCA Globcom is a leader among the overseasvoice/record carriers operating in the United States, itscompetitors for overseas business are: ITT World Com-munications Inc., Western Union International, Inc. (notaffiliated with the Western Union Telegraph Company),TRT Telecommunications Corporation, United States -Liberia Radio Corporation, and the French Telegraph CableCompany. In addition, the American Telephone &Telegraph Company has a monopoly in the internationalvoice -only communications business. The FCC recentlyalso authorized two former domestic -only carriers,Graphnet Systems, Inc. and Telenet CommunicationsCorp., to provide international service, but this is beingcontested by the major carriers.

Basic servicesRCA Globcom's principal overseas communicationsservices include: telegram, telex, private -line teleprinterand simultaneous and alternate voice/data channels,facsimile transmission, program broadcast, televisiontransmission and reception, worldwide marine services,and telephone service between Guam and over a dozenother Pacific points.

Message telegram, the oldest and probably the best-known of theservices, began in the Morse -code era long before the advent ofmodern electronic communications.

RCA Globcom was first in the industry to automate thehandling of international telegrams with a ComputerTelegram System (CTS). This system uses an array ofelectronic data-processing equipment that automaticallyreceives, audits, routes, and transmits telegrams across theworld in fractions of a second. Before the computer, thesame operations took several minutes.

A later auxiliary addition to this system, the AutomaticRetrieval Computer, or ARC (Fig. 1), takes telegrams thatU.S. customers have not filed in the proper internationalformat, electronically converts them to the proper format,and feeds them to the CTS.

RCA Globcom has now nearly completed a high-speedsecond -generation computer system that will provide an

20

Photo credit: Al Garrett

Fig. 3Computer telex exchange (CTE-I I) handles over 80% of the overseas telex calls sent through RCA. System increases speed andaccuracy of telex calls, also adds a number of convenience features.

input-output capability more than 100 percent greater thanthat of the CTS and ARC and will further reduce handlingcosts. A segment of the new system computer, a high-speedautomatic dial -in computer (Fig. 2), has recently beenactivated in the Kingsbridge Communications Center, inPiscataway, N.J., further reducing the processing time ofoverseas telegrams to more than 230 overseas destinations.

Telex is a subscriber -to -subscriber dial -up teleprinter service.

It enables a customer in the United States to transmit andreceive messages to and from any overseas correspondent,directly over private teleprinters in his office. Customerscan literally "talk in writing." From 1964 to the early 1970s,overseas telex grew at the rate of approximately 30 percentannually, and since 1967 has replaced the telegram as theprimary source of the industry's revenues.

RCA Globcom now has direct telex service with more than185 overseas points and connects U.S. subscribers withteleprinters in any of hundreds of thousands of officesaround the world. Since Globcom introduced telex servicein 1950, the number of calls handled by the company hasrisen dramatically from 1500 in the first year to 27.2 millionin 1976.

Telex has become popular with users for a number ofreasons. For the small importer and exporter, the inter-national telex or telegram message offers the fastest andmost positive means of negotiating price, obtaining deliverydates, and providing the information necessary to expediteclearance of imported goods through customs.

Record communications can frequently solve many of theproblems of placing business calls intercontinentally dur-ing non -coincident business hours. For telephone users,the greater the difference in time zones, the greater theproblems. In some places overseas, there are so fewtelephone circuits available that placing a business calloften requires a long waiting time. Selecting telex canproduce contact almost immediately. And, telex is in writtenform, which can be handled at once, or as soon as the officeopens, with reduced chances for misunderstanding.

To handle the proliferating number of telex calls, RCAGlobcom installed the industry's first computer -controlled

telex switching system. Using area codes and numberssimilar to those for making long-distance telephone calls inthis country, subscribers can make direct -dial telex callsoverseas without operator intervention at any point. Today,our subscribers and, by direct interconnection with ourfacilities, those of Western Union's domestic telex and TWXnetworks, can reach more than 90 percent of the world'steleprinters by this automated system.

In addition to increased speed and accuracy, the computersystem provides an array of customer convenience options:

Uni-codes make it possible to dial the most frequentlycalled customers' numbers by just typing a single digit.With this setup, calls go through faster and with lesschance of error.Automatic camp -on keeps trying a busy telex number forabout 3 minutes until connection is made.Telextra automatically takes a call into the computerwhen the circuits are busy and delivers it when the line isclear. It provides confirmation soon after the call iscleared.Stay -connect lets a subscriber call another number whenhe gets a busy signal; he doesn't get cut off and have tomake another connection.Telexgram takes an undeliverable telex call and convertsit to a telegram for easy delivery.Multiple -address service sends the same text to manyoverseas locations quickly and automatically.Departmentalized billing gives customers monthlycharges for overseas telex calls by department in sub-scribing companies.

In late 1975, a completely new Computer Telex Exchange,CTE-I I, (Fig. 3) went into operation at the KingsbridgeCommunications Center in Piscataway. The new systemwas further expanded in 1976, with additional redundantsubsystems, increasing both capacity and reliability.

The CTE-I I is now handling over 80 percent of RCA's dailyvolume of overseas telex calls. When the CTE-I I installationis fully expanded, it will have three times the trunk -handlingcapacity of the original computer system. The new systemhas the modular capacity to handle growth requirements to1980.

21

Fig. 4Computerized message switching system for leased -channel sub-scribers is called AIRCON. System handles high-speed traffic,giving urgent traffic priority and selecting alternate routes if theoriginal route is interrupted.

Leased channels are essentially private lines that permit U.S.subscribers to maintain direct, uninterrupted communications withlocations throughout the world.

RCA Globcom installed the first commercial leased channelin 1948 and still leads the industry today, with leasedchannel service to over 100 overseas points. RCA Globcomhas approximately a 43 percent share of the total industryleased -channel business.

When a customer leases a channel from Globcom, thecompany arranges for everything, including all thenecessary communications equipment at both ends of thechannel. Globcom also assumes end -to -end responsibilityon a continuing basis for optimum performance.

RCA Globcom provides both narrowband teleprinterchannels and wideband or voice -grade channels, whichmake possible a choice of communications modes, alter-nate voice/data, or facsimile with simultaneous teleprinterservice.

Wideband circuits can transmit data at speeds up to 9600bits per second. As many as 24 standard -speed 100 word -per -minute channels can be derived from one voice -gradecircuit, or a lesser number of channels can be provided forhigh-speed printers.

A typical leased -channel application is the digital facsimileservice provided for the National Oceanic and AtmosphereAdministration (NOAA). RCA Globcom furnishes NOAAwith the overseas voice -grade circuit that links the NationalWeather Service in Maryland with the Central ForecastingInstitute in Moscow for regular interchanges ofmeteorological information. This circuit supports the U.S.Weather Bureau participation in the World MeteorologicalOrganization, which contributes to the safety and comfortof intercontinental air travel.

Computer -to -computer communication is increasing.

RCA Globcom is now offering 50-kilobit/s overseas leased -channel service for point-to-point transmission of largevolumes of information. The service is carried overseas bysatellite and is designed for real-time computer -to -computer communications.

RCA Globcom is a major supplier of high-speed digital dataservices that link the NASA tracking stations and switchingcenters around the world. At the end of last year, three 50-kb/s wideband circuits were in operation supportingscientific space programs and projects for NASA. WhileNASA is presently the major user of these facilities, 50-kb/sservice also has broad application for high -volume users.

AIRCON is a shared computerized message -switching system forleased -channel customers.

Introduced by RCA in 1967, AIRCON permits companieshaving their own private teleprinter networks to plug into amaster computer for automatic relaying of messages.AIRCON switching centers (Fig. 4) in New York and SanFrancisco direct information flow and interconnect theoverseas and domestic offices of high -volume subscriberswho need a rapid exchange of information.

One of the most successful AIRCON applications can beseen in the petroleum industry, which uses the switchingsystem to exchange refinery production data, tanker routesand schedules, crew assignments, cargo manifests, and avariety of administrative information between widelyseparated U.S. and overseas locations.

AIRCON computers continuously channel messages totheir destinations and ensure that high -priority messagesare transmitted first. The center routinely handlesthousands of messages a day.

Recent additions to serviceRCA Globcom is now offering Mailgram service to Hawaii.

This service, now offered on an interim basis, enablescustomers in the U.S. mainland and in Hawaii to sendmessages between these points for local delivery by theUnited States Postal Service. The company has alsorequested authority from the FCC to initiate permanentelectronic mail service (EMS) between the U.S. mainlandand other overseas operating points. The company plans touse its existing facilities and those of the United StatesPostal Service for the new electronic mail service. Theproposed EMS is similar to service provided domestically,which uses a combination of telegram service and mail.

Worldwide marine communiations via satellite became a reality withthe inauguration of Marisat service by RCA Globcom in 1976.

For the first time in marine history, ships at sea can enjoyalmost instantaneous two-way worldwide telegram, telex,voice, data, and facsimile contacts with shore points.Communications via the Marisat satellites make this possi-ble. Two Marisat satellites are operational over the Atlanticand the Pacific areas. The third "bird," in orbit over theIndian Ocean, will be used primarily by the U.S. Navy.

22

RCA Globcom is the only Marisat carrier that can providetotal marine communications to subscribers: sale or leaseof shipboard terminals, satellite communications services,and conventional high -frequency, high -frequency cw, andhigh -frequency teletype radio service.

In 1976, the FCC designatedMiami and New Orleans as full -service"gateways" for RCA Globcom.

The new gateway offices in Miami and New Orleans nowgive a greater number of subscribers direct access to the fullrange of Globcom's overseas services with significantlyimproved quality and speed. The new gateways are part of aproposed expansion program in which Globcom requestedauthorization from the FCC to provide additional overseascommunications services directly to customers in impor-tant U.S. metropolitan areas. Globcom previously had fullgateway operations in New York, San Francisco, andWashington, and served private -line customers fromMiami.

RCA Globcom also performs several other communications -relatedactivities through a wholly -owned subsidiary, RCA GlobcomSystems, Inc.

For example, Joint User Service (JUS), a domestic low -speed teleprinter and data network that went into operationin July, 1973, became part of Globcom Systems during1976. JUS can handle line speeds from 50 to 300 baud.

Another activity,Communications Network ManagementService, maintains customer -owned or -leased modems(modulator and demodulator equipment) and multiplexers,which make simultaneous use of a large number ofchannels on a single circuit possible.

The future

While the overseas communications industry has beenestablished for over half a century, today's dynamic up-heavals may produce fundamental changes in its traditionaloperations. The changes are being triggered by basicrevisions in Federal Communications Commission policy,by significant developments in technology, and by theexpanding need for international data communications.

RCA Globcom recently established a new Data ServiceDevelopment group, whose mission is to produce newofferings to meet the user needs of, and so capture a shareof, the emerging data -services market.

The company has concluded a series of overseas transmis-sion tests between New York and Tokyo on a new high -resolution, high-speed digital facsimile system that deliversa typewritten page in about 26 seconds. The new system,called "Quick -FAX," and produced by a Japanese com-pany, can send approximately two pages of typewrittenmaterial or engineering drawings in the same time that thefastest existing equipment takes to send one page, whilesimultaneously providing a superior reproduction. Thetests definetely point to ways of improving the speed,quality, and cost of public overseas facsimile corn-

munications; plans are being examined for offering thisservice on a commercial basis.

RCA Globcom has also concluded agreements withdomestic record communications carriers, subject to theapproval of the FCC, to interconnect facilities for thedelivery and receipt of overseas data and messages. Theagreement with one of the carriers provides packet -switched data -communications service between the U.S.and overseas points. The new packet -switched service isdesigned as an economical means of communicationsamong corn puters and a wide variety of terminals operatingat low and medium speeds. The primary users of this serviceare expected to be multinational corporations, public databanks, and commercial computing -service bureaus.

These recent developments point toward RCA Globcom'snew directions in the communications field. The companyis committed to its pioneering and innovative role in theindustry, introducing new services and expanding its plantwith the addition of advanced -design equipment andtransmission paths.

Reprint RE -23-3-8Final manuscript received June 17, 1977.

Jim Hepburn is Vice President and Technical Director of RCAGlobcom. He joined RCA Globcom in 1941 and served in variousoperations and engineering posts before becoming Manager,Equipment Design, and later Chief Engineer. He has also beenManager, Pacific Coast; Vice President, Pacific Coast; and VicePresident, Operations.Contact him at:RCA GlobcomNew York, N.Y.Ext. 7544

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cessing of musicfor satellite

How do listenersencoding and mo

The success of RCA's entry into thedomestic satellite communication marketrequires careful consideration and plan-ning to provide an economic, flexiblecommunication system that can accept awide variety of signal types. A prime factorneeded for success is the selection of themost efficient method of encoding andmodulating the various audio, video, anddata signals to ensure a given quality ofservice with minimum power andbandwidth.

Advantages ofdigital transmissionHistorically, audio and video have beentransmitted by various modulation techni-ques in which the transmitted carrier is acontinuous function of the messagewaveform. However, the development ofsemiconductor devices over the pasttwenty-five years has permitted the rapidgrowth of digital communication systems,in which the information appears in dis-crete steps of both time and amplitude.

Digital systems have a number of inherentadvantages. They provide a more flexiblechannel in that various kinds of signals-audio, video, or data-can be intermixed intime without impairing each other. This is avaluable asset because the channel then canaccommodate various mixes of trafficloads. Digital signals are less susceptible tochannel noise, and furthermore, terminalnoise and transmission -media noise can beconsidered separately. The quantizingnoise introduced by the digitizing processcan be made as low as desired by the choiceof the codec (code -decode) transfercharacteristic. Transmission -media noisedoes not build up in terrestrial circuitsbecause regenerators, rather thanamplifiers, are used to restore the digitalsignal. The rapid advances in semiconduc-tor technology and LSI make digitalprocessing attractive because of size andcost reduction. Digital signals are also

communicationreact to different methods ofdulating music?

simpler to encrypt and so reduce securityproblems. In the future, as digital switchesbecome more prevalent, all -digitaltelecommunication transmission systemswill be developed.

Digital processing methodsA number of practical audio systems arenow in existence.

For example, the T1 digital telephonesystem was introduced about 15 years agoto increase the capacity of interchangetrunks in densely populated areas. Thissystem provides 24 channels at 1.544 Mb/ son a single twisted pair of wires. Morerecently, a rural -subscriber loop carriersystem providing 40 channels has beenintroduced. This digital system uses anadaptive delta modulation technique toencode the voice signal. Digital telephonetransmission has now developed into acomplete hierarchy of systems, both in thiscountry and in the international network.Higher -speed systems using bit rates ofover 100 Mb/ s are under development.Another application of digital transmissionis the multichannel music -distributionsystem used on the Boeing 747. In thissystem, fifteen high-fidelity channels andcontrol information are distributed to eachseat on a single coax cable at a data rate ofabout 5 Mb/ s. Digital video is still in thedevelopment state, but some systems havebeen demonstrated. Low -resolution Pic-turephone service has been provided on anexperimental basis using 6.3 Mb/ s.

The rapid expansion of digital techniquesand digital signal processing makes them aprime contender for satellite com-munications. At present, most satellitecircuits employ continuous -time waveformmodulation, but Intelsat has introduced adigital system called SPADE for low -volume telephone circuits.

One of the concerns in selecting a digitalsystem over analog is signal quality.

24

Although the signal-to-noise ratios can bedetermined from objective measurements,listeners perceive digital and thermal noisedifferently. In this paper we describe somedigital processing techniques and give theresults of a subjective evaluation of thequality of high-fidelity music received overthese various systems.

Before discussing specific systems, a briefdescription of digital processing may behelpful. A digital signal is defined by bothtime and amplitude. The sampling theoremrequires that samples be taken at twice thehighest frequency in the band with pulses ofzero width, and that an ideal lowpass filterbe used to eliminate high -frequency com-ponents. In practice, realizable lowpassfilters require a guard band, provided bysome over -sampling. The T1 telephonesystem, with sampling at an 8 -kHz rate,provides a useful channel bandwidth of 3.5kHz. The sample pulsewidth should be lessthan 10% of the sampling time to avoidfrequency distortion of the reconstructedsignal. In most digital processing systems,the original continuous -amplitude time -sampled signal is converted to a number ofdiscrete amplitudes by a coder.

The simplest coding method, pulse codemodulation, divides the sampled signal intoa number of equally spaced levels.

PCM, as it is known, produces a staircaseapproximation to a linear distortionlessfunction. The error between the staircaseand the linear characteristic producessignal -related quantizing distortion that is

perceived differently from the morefamiliar random thermal noise developedin analog channels. The quantizing noisecan be made as small as desired by in-creasing the number of quantizing levels.However, this increases the number of bitsrequired to encode the signal, and conse-quently, the bit rate and bandwidth re-quired for the channel.

Many variations of PCM have beenproposed to compress the amount of infor-mation that must be transmitted.

For signals that have correlation betweensamples, as with audio and video,differential pulse -code modulation(DPCM) has been effective for bit -ratereduction. Instead of encoding the directsample, the difference between the inputsample and a predicted signal, based uponpast samples, is coded. When the differencesignal is coded into one binary bit, theprocess is termed delta modulation (DM).In this case, the output bits convey thepolarity of the difference signal. Inordinary DM, the decoder moves theoutput signal a fixed increment up ordown, depending upon the bit stream.

Companding reduces quantizing noisewithout reducing step size excessively.

In both DM and PCM, the step size affectsthe level of quantizing noise. In DM, thedynamic range is limited by quantizingnoise and slope overload distortion. If thesteps are small, the quantizing noise is low,but a very high sampling rate would berequired to follow a rapidly changing

Dick Klensch has worked in a wide variety of researchprojects since joining RCA Laboratories in 1952. Hiswork has included microwave, television, communica-tion, and display systems. He has been doing researchin satellite audio and video communication techniquessince 1975.

Contact him at:Communications Research LaboratoryRCA LaboratoriesPrinceton, N.J.Ext. 2909

Ed Rogers has a wide research background. He beganhis work at RCA in 1945 in acoustic and ultrasonicresearch, then worked on machine recognition andsynthesis of speech, and more recently has donesystem analysis and design. He is now investigating thesystem aspects of broadband information systemscovering data, speech, audio, and two-way CATVsystems.Contact him at:Communications Research LaboratoryRCA LaboratoriesPrinceton, N.J.Ext. 2226

signal. On the other hand, if the samplingrate is too low, the received signal cannotaccurately follow the rapidly changingsignal. DM coders that incorporate avariable step size, which is essentially acompanding operation, are called adaptivedelta modulators (ADM).

In PCM a similar problem exists. If thequantizing steps are made very small toreduce the quantizing noise, the number ofbits per sample becomes large. For exam-ple, for linear quantizing steps, 12 bits persample are required to provide about 70 dBSI NQ. The number of levels, and hence thenumber of bits per sample, can be reducedby using unequal level spacing. Thisreduces the bit rate without reducing theperceived signal quality. A form of com-panding, it essentially compresses thetransmitted signal and then expands thereceived signal. This method increases thesize of quantizing error for large signalsand reduces it for small signals, and so ineffect yields a constant signal -to -quantizing -noise ratio over a wide dynamicrange.

Optimum companding functions aredifferent for different kinds of signal dis-tributions. For example, audio signalsrequire a logarithmic compression functionthat produces a quantizing distortionproportional to the signal level. Fortelephone systems, two modifiedlogarithmic functions are in use. In theU.S.A., "µ-law" compression is frequentlyused, whereas in Europe an "A -law" func-tion is more common. The functions are

Authors Klensch (left) and Rogers.

25

similar at high levels, but the A lawbecomes linear at low levels. The µ- and A -law characteristics have been developed forspeech, with typical values ofµ = 225 and A= 100. Fig. 1 gives graphs of severalcompanding functions. For music, alogarithmic characteristic (the curve at thetop of Fig. 1) was used with various

numbers of levels of approximation. A µ-law characteristic with µ = 1000 is shownfor comparison.

All of the digital signal processors outlinedabove are candidates for satellite com-munication systems. Digital satellitetelephone systems are now in use. One,

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Fig. 2Experimental test arrangement provides three signal types for listener evaluation afterstarting with the same high -quality input (left). FM signal (top) is produced by addingweighted noise to the analog channel. ADM signal (middle) is produced by a codec capableof operating at varying bit rates. PCM signal (bottom) is produced by putting analog signalthrough sample -and -hold circuit, analog -to -digital converter, computer processing, anddigital -to -analog converter.

Intelsat's SPADE system, uses a 7 -bit A -law companded PCM codec with a bit rateof 56 kb/ s. This signal is compatible withthe T1 terrestrial digital hierarchy.

Evaluating the digitalprocessing methods

Although speech, video, and datadominate the current interest in satellitecommunication, there is a possibility ofproviding high-fidelity music channels forradio broadcast networks in the future. Anumber of subjective evaluations have beenreported to determine the value of variousdigital techniques for speech systems, butthere does not appear to be any informa-tion on subjective evaluations of musictransmitted over digital systems.Therefore, the experiment described herewas performed to compare the processedmusic signal received over analog anddigital circuits. The digital processors wereADM, PCM, and companded PCM. Theoutput from these processors was com-pared with an analog signal simulating thetype of signal and noise received from aconventional FM receiver.

All three processing circuits (FM, ADM, andPCM) were set up simultaneously so thatpairs of processed signal variations could beselected for encoding on parallel tracks of ahigh -quality dual -channel tape recorder.

Dolby noise reducers were included toprovide a test tone -to -noise ratio of 70 dBat a test -tone level producing 3% distor-tion. Fig. 2 gives a functional diagram ofthe arrangement. The analog signal sourceis shown at the left. An FM signal wassimulated through the top channel byadding various amounts of weighted noiseto the analog signal. The signal to thedigital processors was band -limited by the15 -kHz lowpass filter (to prevent aliasing).The response of this filter is 3 dB at 15 kHzand 50 dB down at 16.5 kHz. The band -limited signal at the output of the filter issplit and sent to both the ADM and PCMprocessors.

The ADM codec is a hardware realizationof a design developed at RCA Laboratoriesby W.G. McGuffin. It uses an adaptiveprocessor to adjust step size and is capableof operating at rates between 50 and 300kb/s.

The PCM processing system is the bottomchannel in Fig. 2. This channel employsA/ D and D/ A converters in conjunctionwith a PDP-1 I / 20 minicomputer to

26

produce various companded PCM signals.The band -limited signal from the filter isadjusted to provide a maximum level of±10 volts at the input to a high -precisionsample -and -hold circuit. The precision ofthe sample -and -hold circuit is specified asan aperture uncertainty, which is related toits response -time uncertainty. It shouldhave a value suitably small, consistent withthe highest rate of change of the inputvoltage and the number of bits to which theinput will be digitized. This can be ex-pressed by:

[d(V sin 27rft)/ dt][A] < [V(n - 1]

whereV = peak input voltage

f = maximum input frequencyn = total total number of bitsA = aperture uncertainty

An 0.2-ns aperture uncertainty is thereforejust adequate to sample a 15 -kHz audiosignal with 16 -bit accuracy.

The choice of the number of required bitsresulted from the signal-to-noise goals andevidence indicating that somewherebetween 12 and 14 bits are necessary for"high fidelity." The availability, atreasonable cost, of a 16 -bit A/ D converterhaving an 8 -us conversion time made itpossible to go beyond what the mostcritical listeners had indicated was man-datory for complete freedom of quantiza-tion effects. Indeed, experiments madewith the D/ A converter connected directlyto the 16 -bit A/ D converter, whose filteredoutput was compared to the original un-sampled high -quality analog input,demonstrated that 12 bits was good enoughfor most recorded sound. It should benoted that any number of bits (up to 16)could be selected by the use of toggleswitches.

The PCM system described provides aflexible facility for real-time processing ofhigh-fidelity audio. Assembly -languagesoftware, provided by S. Cabo, allowsseveral options for effecting different com-panding laws by providing computer -generated translation tables with linear,log, or mixed linear/ log characteristics.Tables can also be generated in a "free"manner by inserting the table values fromthe teletype terminal. Companding is per-formed in real time by table look -up at amaximum sampling rate of about 33kilosamples/ s. Because of the limitedmemory capacity of the PDP-11 / 20, the

2000

1000

500

200

100

50

20

1010

LINEAR400 KB/S

0.1dB/STEP333 KB/S

FREE 12282 KB/S

FREE 17267 KB/S

0.3 dB/STEP300 KB/S

1

100

LINEAR PCM INPUT LEVELS

1000 3000

Fig. 3Five PCM codes were used in the listening experiment. Linear 400 is a 12 -bit linear code (11level bits plus sign bit), 0.1 dB/step codes use pure log companding down to the point wherelinear size limits companding, and free -12 and -17 use semifree companding with linear,0.2 -dB, and 0.4 -dB steps.

16 -bit samples from the A/ D converterwere truncated by the computer to 12 bitsfor the translation table.

The experiment compared five PCM, threeFM, and two ADM signals.

About 25 variations of companding basedupon the top curve of Fig. 1 were tried forpreliminary tests, and after considerablescreening, five PCM encoding plans wereselected for final testing. One was linearwith 12 -bit samples and the other four werecompanded codes with 10, 9, 8.5 and 8 bitsper sample. Assuming a sampling rate of33.3 kilosamples/ s, this results in bit ratesof 400, 333, 300, 282, and 267 kb/ s. Thedistribution of levels for these five PCMcodes are shown in Fig. 3.

Three FM signal-to-noise ratios and twoADM bit rates were chosen for comparisonwith these PCM signals. The "qualityfactors" were 60, 50, and 40 dB S/ Nfor theFM signals and 200 and 300 kb/ s for theADM. This total of 10 different processingtechniques for evaluation gave 45 com-parison pairs for the balanced test.

Subjective evaluationSubjective evaluation has been frequentlyused to measure the relative preference ofthings that cannot be measured objectively,but with various degrees of success. Anumber of accepted methods are available,depending upon the purpose of the experi-ment. Our primary objective in these testswas to rank the various systems without

attempting to determine the psychologicalfactors underlying the judgment.

Two methods were used simultaneously inthese tests.

In the primary test, listeners were givenpairs of recordings and asked to make apreference judgment with a forced deci-sion. In the second test, listeners were askedto rate the recordings on a five -level scalegraduated from excellent to not acceptable.The goal of this experiment was to provideinformation that could be used to estimatethe minimum bit rate, and hencebandwidth of a digital channel, that wouldprovide high -quality audio perceptuallyequivalent to that obtained from a givenanalog channel.

The test material was chosen to provide afull range of music types-it included soloinstruments, small groups, jazz bands, andclassical orchestras.

Excellent third -generation master tapes offive stereo albums were provided throughthe courtesy of RCA Records. Since theoriginal stereo tapes were recorded with theDolby noise -reduction system, they were"de-dolbized," mixed, and then rerecordedmonaurally for test samples. After screen-ing tests were performed to obtainselections that produced noticeabledifferences between systems, the followingselections were chosen:

1) Guitar, Chet Atkins, "Godfather"

2) Guitar, Chet Atkins, "Sting"

27

3) Trumpet, Buddy Rich Band,"Something"4) Chicago Symphony Orchestra,"Mahler's Symphony #4"5) Jazz, Basie Trio, "O.P."

These selections provide a wide range ofphysical and psychological factors, such asloud -soft, full -thin, and dynamic at-tributes.

A two -minute test sample was made, using24 seconds of each selection. This testsample was then used as source material forthe system comparisons. The outputs fromthe various processing systems werearranged in pairs, cut up and reconstructedwith a random sequence of 45 two -minutetest segments that were evaluated in threehalf-hour listening sessions.

A heterogeneous group of 35 listeners,made up of males and females covering awide range of ages, was selected at randomfrom the laboratory personnel. There wasno training period involved in these tests,but some listeners were scientificallyoriented and presumably may have usedspecial clues for judgment. After someinitial analysis of the data, the overallgroup (A) was divided into two sections,with 20 listeners classified as unskilled (U)and the remaining 15 listeners classified asskilled (S).

The prerecorded test tapes were played forthe listeners through high -qualityheadphones. Each listener station had avolume control and switching betweenchannels. Headphones were used, ratherthan loudspeakers in a living -roomenvironment, because the program levelrequired to provide a 60-db SI N in therooms available would have been ex-cessive.

Results

In general, preference testing of severalobjects simultaneously generates twopossible problems. First, are there signifi-cant differences between the systems thatcan be uniformly judged by a group oflisteners? It is not clear that this criterion issatisfied when comparing analog anddigital systems; it may be like comparingapples and oranges. Second, are thelisteners consistent in their judgment ofpreferences? If the systems are notsignificantly different, then the data can beinconsistent and circular trials develop inwhich 1 is preferred over 2, 2 is preferredover 3, and 3 is preferred over 1.

Table IRanking of processing methods puts FM and PCM at top; seeFig. 4 for graphical interpretation of data.

Preference %A U S

Processingmethod

Data rate(kb/ s)

SI N(dB)

75 77 74 PCM 40073 73 74 FM 6071 74 67 FM 5067 67 66 PCM 33347 49 44 FM 4039 39 39 ADM 30039 35 43 PCM 30038 37 41 PCM 28235 33 37 PCM 26716 16 15 ADM 200

To rank the various systems on some kindof a relative preference scale with knownconfidence intervals, the data from thelistening tests was collected in matrix formshowing the percentage of time the columnstimuli A was preferred over the rowstimuli B. The data was subdivided byselection number and listener group andthen summarized by a tournament methodin which the total number of times aparticular stimuli is preferred over all otherstimuli is summed and used as a rankingscore. The ranking of the various systemsby this method is shown in bargraph formin Fig. 4. The scores for each selection(numbered from left to right) are shown inclear bars and the combined results for thefive selections are shown as solid bars.Although this method does not indicate thestatistical significance, it shows dramatical-ly the effect of the selection and processingmethod. The data is shown grouped byprocessing method rather than preferencerank. Apparently selections 3 and 4 werepreferred on the lower -bit -rate PCM.However, selection 3 had a very lowpreference on the ADM. The rank orderingfrom the combined average matrix is givenin Table I.

The category judgment subjective evalua-tion produced an independent preferenceranking; Fig. 5 gives a summary of themean, the standard deviation, a , and the95% confidence intervals. There is nosignificant difference between FM with 60 -dB and 50 -dB S/N and 400 -kb/ s PCM;however, these three are significantly betterthan all of the other systems. This testmethod ranks the ADM higher than theranking obtained from the paired -comparison tests. The figure shows verylittle significant difference between FM

with 40-db SI N and the other digitalprocessing methods.

ConclusionsThe evaluation test shows that listenersperceive very little difference between anFM signal with 60 -dB or 50 -dB S/N and a400-kb/s linear PCM signal.

Both the paired -comparison method andthe category -judgment test showedremarkable consistency in ranking. Theprocessing systems used in these tests werethe best ten selected from many trialsystems evaluated in preliminary screeningtests. A study of Fig. 4 shows considerablevariance due to music selection-it appearsthat the greatest discrimination resultedfrom the purer, clearer solo instrumentsand less distinction was obtained from thelarge jazz bands and orchestras. This isbecause the broad audio spectrumproduced by many instruments masks thedistortion introduced by the digital sysem.Vocal selections did not provide muchdistinction between systems.

There is no question that digital processingsampled at the Nyquist rate producesconsiderable distortion. This can bereduced by oversampling, but it is im-practical because of the excess bandwidthrequired. When reproducing pure tones,digital systems are unquestionably inferiorto analog systems; however, for variousother types of music, digital systems can bequite acceptable.

A rough comparison shows that the FM andPCM bandwidth requirements are equal.

The prime purpose behind the subjectiveevaluation was to determine the power andbandwidth required to transmit a given

28

100

90 -

80 -

70 -

60

88 50-

z 40-w

LL 30 -wa. 20-w

5 10 -

0 Aluls60

A U I s50

Alu Is40

A lUr3400

AIU S333

AIUIS300

FM PCM

PROCESSING SYSTEM

Aro.282

A106267

AluISIA U S

300 200

ADM-.

Fig. 4Average selection preference (dark bars) showed best -quality FM and PCMessentially equal in paired -comparison tests. However, individualselections (white bars, numbered from left of each group of five) receivedvarying preferences with different processing systems. On horizontal axis,A, U, and S are for "all," "unskilled," and "skilled" listeners; numbers for FMare S/N in dB; numbers for PCM and ADM are sampling rates in kb/s.

quality of audio over the different kinds oftransmission links. An estimate of therelative efficiency of digital and analogsystems can be made by considering a 15 -kHz music signal. If we assume that fordigital transmission an intrinsic bandwidthequal to the bit rate is a practical, realizablevalue, then a system with coherent phasedetection is capable of providing a bit errorrate (BER) of about 10-6 with a carrier -to -noise ratio of 12 dB. The subjective evalua-tion shows that a 400 -kb/ s PCM signalproduces a baseband signal that is sub-jectively equivalent to an FM system with a50 -dB N program level or, because musichas a 13 -dB peaking factor, a peak SI N of63 dB. The digital signal could betransmitted in a bandwidth of 400 kHz at aC/ N of 12 dB. If a lower BER is required, itcan be achieved using error -correcting codetechniques, which will require someadditional bits.

Assuming a Carson bandwidth of 400 kHzfor an FM signal, the modulation index forthe 15 -kHz baseband channel is about 12.Although this may not be the most efficientdesign for an FM system, it does allow thetwo systems to be compared in a commontransmission bandwidth. At a modulationindex of 12, a C/ N of 25 dB would providea peak S/ Nof 63 dB in the baseband signal.Assuming an improvement of 13 dB SI Nthrough using pre -emphasis, the FMsystem using a 400 -kHz transmissionbandwidth would require a CI N of 12 dB,which is identical to the digital system.

FM 60dB

PCM 400 KB

FM 50 dB

FM 40 dB

ADM 300KB

ADM 200KB

PCM 267 KB

PCM 333 KB

PCM 282KB

PCM 300KB

cr

,-95% CONFIDENCE INTERVALi 7 a

EX GOOD FAIR

2 3CATEGORY

POOR NOT

4STABLEACCE

Fig. 5Preference ranking by category judgment showsno significant difference among 60 -dB FM, 50 -dBFM, and 400 kb/s PCM, but ranks ADM higherthan paired -comparison tests (Fig. 4).

The comparison made here is quite crude.There are many trade-offs of power andbandwidth possible for these two basicsystems. The PCM signal was a linearsignal without companding. One of thelimitations of the PDP-11/ 20 system wasits lack of digital storage; hence the need totruncate to 12 bits. The low levels, near 60dB down, had minimum steps of severaldB. It is conceivable that processing 14 or16 bits per sample with companding to 12bits or less per sample would provide abetter -quality signal.

The results of this work show that digitalprocessing of music can be achieved with ahigh degree of listener acceptance. At thepresent state of the art, analog systemsprobably have a slight edge over the digitalsystems reported here. If serious interestdevelops in satellite networking of high-fidelity music, more research into digitalprocessing systems should be encouraged.In particular, work on better compandingalgorithms is desirable. The compandingprocedures reported here were reallyshallow, in that only variations oflogarithmic functions were tried by tablelook -up.

The conclusions are clear. For manyapplications, digital systems can providecustomer -acceptable monaural music of agiven quality at essentially the same powerlevel and bandwidth required by an FMsystem.

AcknowledgmentThe advantages of a large integratedresearch laboratory such as RCALaboratories are appreciated when oneattempts a task covering several disciplines.The resources of these laboratories wereused extensively in this work. We ap-preciate the leadership and interestprovided by K.H. Powers and W.D.Houghton of the CommunciationsResearch Laboartory. We also wish tothank all of the people who volunteeredtheir time to listen to 90 minutes ofrepeated playings of the same five musicalexcerpts. Special appreciation is expressedto several individuals whose help greatlyexpedited the progress of the work: toW.G. McGuffin for circuit hardwaredevelopment; to H.E. White for aid ininterfacing the digital circuitry to the PDP-11 / 20 computer; to S. B. Calo for develop-ing software for the processor; to J.J.Mezrich for consultation during the designof the tests and computer analyis of thepaired -comparison data matrices; to L.Schiff and J.J. Gibson for discussions onsystem aspects of the three processingsystems; to L. L. Stetz for aid in obtainingobjective measurements and preparation oftest tapes; to E. Cattani of RCA Recordsfor providing the music source tapes andDolby noise -reduction equipment; and toS. L. Roberts for recruiting and schedulinglisteners, and also typing the manuscript.

Reprint RE -23-3-10Final manuscript received February 4, 1977.

29

Keeping abreast of the new technologyin my field is quite important to my job performance.

It is also quite important to my future career goals.

My management places only moderate emphasison the importance of my staying up-to-date.

Technical information bearing directly on my jobis the most important type of information I need,and having efficient access to it is extremely important to me.

I obtain most of my job and career information through reading andthrough informal discussion.

The five most useful information sources for me are (in order)my own files, engineers in my work group,books, handbooks and manuals,and engineers at my location outside my work group.

I get most of my technical information about RCAfrom discussion with associates and from the RCA Engineer.

I get much of my nontechnical informationabout RCA from the grapevine, from RCA Trend, and from my supervisor.I think other sources ought to be more productiveso I would have to rely less on the grapevine.

I spend eleven hours per week readingmaterial that is relevant to my job and career.More than half of that reading is technical information,and more than half is done on my own time.

The greatest obstacle I haveto adequate reading is TIME. There isn't enough, either at work or outside.

Engineering InformationSurvey results

H.K. Jenny) W.J. Underwood

30

These are some typical responses from more than 50% of theengineers who completed the Engineering Information Surveydescribed in the accompanying box. This article, which is thefirst of a series, analyzes the responses to the followingquestions:

How important is keeping abreast of new technology?How important is efficient access to various types of infor-mation?What information sources are used and what is their value?How many hours do engineers spend reading various types ofmaterial?To what extent are engineers staying up-to-date?

Engineers and their supervisors work in fields of constantlychanging technology. For many, this changing technology hasthe following characteristics: its rate of change is high, itscomplexity is increasing, and its volume is expanding.Technology is changing from tangible to intangible, visible toinvisible, concrete to abstract, manual to automatic. Informationconcerning new technology proliferates at a similarly high rate.The number of technical journals has doubled every 15 yearssince 1700. In 1970, some 3500 technical books were published.Books in science increased by 55% during the 50s and by 117%during the 60s. In chemistry about 250,000 books, articles, andpapers are published each year. Patents have doubled everydecade since World War II, and filing rates have reached 3000 aday.

How has living in the above milieu affected the attitudes andopinions of RCA engineers and their supervisors? How impor-tant do they think it is to keep up with the changes? The firstthree items on the Engineering Information Survey soughtanswers to these questions.

In these questions, engineers refers to all professional,technical, nonsupervisory employees working in the physicalsciences. It includes those working in research, in design anddevelopment, and in manufacturing. Supervisor refers to alllevels of supervision of the engineers, leader refers to the firstlevel of supervision, and manager refers to all higher levels.

How important in your present job is keeping abreast of newtechnology in your field?

Importance

ExtremelyQuiteSomewhatSlightlyNot at all

Engineers Leaders Managers

32% 39% 40%

44 42 43

18 15 15

5 3 2

1 1 0

More than three -fourths of each occupational group ratedkeeping up-to-date in the two highest degrees of importance. Itis interesting to note that supervisors assign new technology ahigher degree of importance for their jobs than do engineers.

That practically all respondents (99%) would assign some jobimportance to keeping up with technology is probably notsurprising. The importance it would have for their future careerswas somewhat less predictable.

Reprint RE -23-3-20Final manuscript received September 29. 1977.

Thanks for taking that half hourDuring the first half of 1977, engineers and their supervisorsthroughout RCA responded to a questionnaire concerningthe sources that supply information needed in their jobs andcareers. This Engineering Information Survey wasdeveloped by the Technical Information Programs unit ofCorporate Engineering. The purpose of the survey was todetermine engineers' information needs for use in shapingprograms aimed at satisfying these needs.

The questionnaire was completed by over 3000 individuals,about 75% of RCA's engineers. Returns were sufficientlybalanced across such parameters as location, division,discipline, age, type of work, and job level to truly representthe RCA engineering population.

The major results of the survey will be reported in a series ofarticles in the RCA Engineer. These articles will presentcorporate -wide data. Additional reports will be made tolocal management, which will review location- and division -level results.

The staff of Corporate Engineering expresses sinceregratitude to all who responded to and administered thequestionnaire. Completing a detailed questionnaire caninterfere with business and personal pressures. The out-standing cooperation of RCA engineers resulted in anunusually high return rate and therefore credible data.

How important to your future career goals is keeping abreast ofnew technology?

ImportanceExtremelyQuiteSomewhatSlightlyNot at all

Engineers370/0

4714

2

1

Leaders

38%4712

3

1

Managers28%5218

2

0

Combining the two highest degrees of importance, engineersand leaders regard keeping up-to-date as more important totheir futures than to their present jobs. Managers assign it onlyslightly less importance to their future compared with theirpresent jobs, but concur that is is quite important.

Given that the respondents at all three organizational levelsconsider keeping up with new technology to be very important,how much emphasis on it do they experience from theirmanagement?

How much emphasis does your management put on theimportance of your staying abreast of new technology in yourfield?

Emphasis

Very strongStrongModerateMinorNone

Engineers7%

21

372311

Leaders Managers

12%27 2836 3921 15

8 5

7%

31

ThiriK it Would be,

berer if you used cos/505

in 1,5I,ancl wo might -also

consider CCD 61011100."

How important to your job is keeping up with technology?

Less than half the respondents in each occupational groupperceive a strong management emphasis on keeping up -to -date -36% to 39% regard the emphasis as moderate. Theemphasis is felt strongest by managers, less by leaders, andleast by engineers. Apparently upper management emphasizeskeeping up with new technology, but the urgency atrophies as itpasses downward through the organization.

The above responses clearly show that keeping abreast oftechnological change is regarded as quite important byengineers and their supervisors for the sake of both their presentand future jobs. Middle managers seem to place importance onkeeping updated but may not act to emphasize that importanceto their subordinates.

Keeping abreast of technology, or anything else, requireshaving access to relevant information. The major purpose of theEngineering Information Survey was to explore access toneeded information, not only technical information, but othercategories that also seem relevant to job and career. Fivecategories of information were predefined in the survey:

Technical-related to one's immediate jobTechnical-otherBusiness-related to RCABusiness-related industryProfessional-the professional field of engineering

Respondents were asked to indicate the importance of access toeach.

How important to you is having efficient access to the variouscategories of information?The alternatives were: Extremely, Quite, Somewhat, Slight, Not.The percentages responding Extremely and Quite combinedare as follows:

(%) Engineers

95 Technical-Job75 Technical-Other41 Professional36 Business-RCA28 Business-Other

(%) Leaders

94 Technical-Job75 Technical-Other55 Business-RCA41 Professional40 Business-Other

(%) Managers

91 Technical-Job71 Business-RCA67 Technical-Other54 Business-Other39 Professional

All three groups ranked job -related technical information asmost important. In fact, more than 50% of each group assignedthat category the highest scale position- Extremely Important.It was the only category ranked in the same position by allgroups. The professional category is more important toengineers, less to leaders, and least to managers. Conversely,business information about RCA was ranked highest bymanagers, lower by leaders, and lowest by engineers. Thesepositionings seem logical, considering the responsibilities ofeach group. An interesting result is that more categories areimportant to a greater percentage of managers; more than 50%responded to four categories. Three categories drew more than50% of leaders and only two did so among engineers.

We now examine the methods and sources for obtaininginformation. Again using the previous information categories(Technical-Job, Technical-Other, Business-RCA,Business-Other, Professional), the study asked:

For each category, what percentage of your information isreceived through:

Reading?Discussions with other engineers?Educational courses?Business meetings?Professional society activities?

The responses were highly similar among engineers, leaders,and managers, and therefore are shown consolidated. Numbersin the table are the average percentages of information receivedvia each method.

Technical TechnicalMethod job other

Business BusinessRCA other Professional

Reading 4 0 % 48% 41% 55%

Discussions 34 25 36 23

Courses 8 10 1 1

Meetings 8 5 13 6

Societies 4 5 1 3

51%

19

19

4

8

Reading is clearly the primary method used, with informaldiscussions second. Together they account for 70% or more ofthe information acquired. Reading and discussions are inverse-ly related across categories. Reading is most productive forinformation that is not immediately related to job and company(Business-Related Industries, Professional). Discussions aremost productive for Technical-Job Related and RCA-Business information.

32

Business meetings are the largest of the three minor contributors with their greatestutility in RCA-Business information. Among occupational groups (data not shown)business meetings were substantially more productive for leaders and managersthan for engineers. Conversely, educational courses were more productive forengineers than for leaders and managers.

These five methods do not exhaust all possible methods for obtaining information.However, the totals of each column show that 88% or more of the information in thesecategories is obtained by the five methods listed.

Another question in the survey probed information sources in substantial detail.Thirty-two possible sources for obtaining needed information were listed.Respondents were given a four -point value scale (Very Valuable, ModeratelyValuable, Somewhat Valuable, Little or No Value). They were asked to assign a valueto each source. In the following table, the 32 sources are listed in rank order by thepercentages of engineers assigning the top two scale positions (Very Valuable andModerately Valuable). The table also shows the sources that leaders and managersranked substantially differently from engineers.

How valuable to you is each of the following sourcesinformation?

for obtaining useful

%

EngineersSource %

LeadersSource %

ManagersSource

93 My own files87 Engrs. in my group78 Books76 Handbooks/manuals62 Engrs. at my location60 Data sheets/appl. notes 60 Internal meetings58 Supervisors in my group56 RCA library 55 TRs and EMs55 Catalogs 53 Supvrs at location50 Standards handbooks 50 External meetings

46 Internal meetings 47 Ext. meetings45 Sales literature 45 Supvrs. at location 45 Data sheets/appl. notes45 TRs and EMs 44 Engrs. at other locations45 External journals41 External papers 39 Standards handbooks 40 Catalogs38 External meetings 39 Sales literature 39 Standards handbooks37 External courses 38 RCA papers37 Internal courses35 RCA standards32 Engrs. at other locations 32 External courses 34 External courses31 External libraries 32 Internal courses31 Proceedings30 Military Specs. & Stds.29 Supvrs. at my location 29 External libraries26 Professional societies25 RCA journals

23 RCA papers22 External consultants14 RCA contract reports13 Supvrs at other locations11 External contract reports4 RCA editorial reps.

Horizontal lines at the arbitrary 50% and 25% response levels divide the sources intothree groupings that might be considered very important, moderately important, andslightly important, respectively. There is no doubt among these respondents that theengineers' own files and other engineers in their immediate groups are most

Hans Jenny has experience as a designengineer, engineering leader and manager,and Chief Engineer and OperationsManager of RCA's solid-state microwaveproduct line. His present position ofManager, Technical Information Programs,uses this background to assist RCAengineers in their and the Corporation'sefforts to remain viable and competitive.Contact him at:Technical Information ProgramsCorporate EngineeringCherry Hill, N.J.Ext. PY-4251

Bill Underwood has a background thatcombines engineering and behavioralscience. Since 1973 he has been associatedwith Corporate Engineering and is now theDirector of Engineering ProfessionalPrograms. Previously, he was in CorporateIndustrial Relations, specializing inmanagement training and organizationaldevelopment.Contact him at:Engineering Professional ProgramsCorporate EngineeringCherry Hill, N.J.Ext. PY-4383

33

valuable. In fact, more than 50% of leaders, managers, andengineers assigned the highest scale value to their own files.

As noted previously, leaders and managers were in substantialagreement with engineers except where indicated. However,some of the sources differ systematically by occupationalgroup. The value of external meetings and supervisors asinformation sources increases as organizational level increases.Conversely, standards handbooks vary inversely withorganizational level as an information source. Also, educationalcourses, both internal and external, are valued more byengineers than by supervisors.

A prominent feature of the results (not revealed in the table data)is the distribution of response. For most sources, an appreciablenumber of responses existed at each scale position. In otherwords, deviation from the mean is large. The interpretationwould seem to be that different people find useful information indifferent places. While some of the sources are highly valued bymost, none can be considered to have insignificant value.

A number of sources were examined in regard to their value forsupplying information about RCA. The first set concernedtechnical information and the second concerned nontechnicalinformation. Regarding technical information about RCA,respondents were given a list of nine sources and were asked toindicate which they used and which were most important.

From which of the following sources do you get the majoramount of technical information about RCA? Also, indicatewhich are most important.

EngineersUse Import.

LeadersUse Import.

ManagersUse Import.

Discussions with assoc. 1 1 1 1 1 1

RCA Engineer 2 2 2 3 2 3

RCA Trend 3 5 4 5 4 6

TRs & EMs 4 3 3 2 3 2

Discussions with super. 5 4 5 4 5 4

RCA educational courses 6 6.5 7 7 8 8

RCA seminars & lectures 7 6.5 6 6 6 5

RCA Review 8 8.5 9 9 9 9

RCA Tech. Abstracts 9 8.5 8 8 7 7

Numbers in the table are rank orders. Discussions withassociates and the RCA Engineer were the first and secondchoices for each group in terms of use. RCA Trend and TRs andEMs were ranked third and fourth, but the order differs betweenengineers and supervisors. All groups assigned fifth position todiscussions with supervisors. At least 50% of each group agreedwith these five sources.

For engineers and leaders, the top five sources ranked by usewere also considered the top five in importance. Managersagreed, except for elevating RCA seminars and lectures in placeof RCA Trend.

To examine sources of nontechnical information about RCA,the survey presented thirteen sources and asked respondents:

From which of these sources do you get most of yournontechnical information about RCA? From which would youprefer to get it?

The primary obstacle to adequate reading for keeping up to dateis lack of time.

EngineersUse Prefer

LeadersUse Prefer

ManagersUse Prefer

Grapevine 1 9 1.5 11 6 9.5

RCA Trend 2 3 3 3 3 3

Your supervisor 3 1 1.5 1 1 1

RCA Family News 4 5 5 4 4 4

Bulletin boards 5 4 7 5 10 8

RCA Communicate 6 6.5 6 6.5 5 5

Company meetings 7 2 4 2 2 2

Local newspapers 8.5 10 11 9 11 11

RCA Engineer 8.5 6.5 8 6.5 8 6

Electronic News 10 11 10 10 9 9.5

RCA annual report 11 8 9 8 7 7

Radio, tv 12 12 12 12 12 12.5Community gossip 13 13 13 13 13 12.5

The grapevine is a primary source for engineers and leaders, butnot for managers. Managers select their supervisors as theprimary source and relegate the grapevine to sixth position. Allgroups place supervisors and Trend among the top threepositions regarding use. RCA Family News is ranked in the top 5by all groups. Three sources vary organizationally. Companymeetings and the RCA annual report are used more bymanagers, less by leaders, and still less by engineers. Converse-ly, bulletin boards are useful in the reverse order. RCACommunicate is middle -ranked by all groups.

The occupational groups are in strong agreement on rankingthese sources according to preference. All rank supervisors,company meetings, and RCA Trend first, second, and third,

34

respectively. Interestingly, that is exactly the use ranking bymanagers. All agree that the grapevine should be a far lesssignificant source.

Since reading was anticipated to be a widely used method forobtaining information, the survey inquired into the timerespondents spend reading, and obstacles, if any, in doing so.

On the average, how much time during and after working hoursin a typical week do you spend reading the various types ofmaterial listed below? Also, approximately how much of thistotal reading time is done during working hours?

EngineersTotal Work

LeadersTotal Work

ManagersTotal Work

Technical -Job 5.0 3.3 6.0 3.6 6.4 3.6

Technical -Other 3.0 1.0 2.9 1.2 2.6 1.0

Business -RCA 0.9 0.6 2.0 1.4 3.3 2.4

Business -Other 1.1 0.3 1.6 0.6 1.9 1.0

Professional 1.5 0.9 1.4 0.5 1.9 0.5

Total 11.4 6.1 13.9 7.3 16.0 9.0

53% 53% 56%

Numbers in the table are hours averaged across responses.Engineers average 111/2 hours per week, leaders read about 21/2hours more than that, and managers average about 2 hoursmore than leaders. Engineers do a little over 50% of their readingduring work hours; all three groups do more than 50% of theirreading only for job -related technical and RCA businesscategories. Managers also do more than 50% of non -RCAbusiness reading during work hours.

Job -related technical materials account for the largest alloca-tion of reading time for all three groups. The second largestallocation of time is for non -job -related technical reading forengineers and leaders and RCA -related business for managers.Taken together, these first and second categories account forabout two-thirds of reading time.

Eleven to sixteen hours per week is a substantial amount of timedevoted to reading. Even the six to nine hours of reading duringwork represents 15% to 22% of a 40 -hour work week. Apparentlythe claims of extreme proliferation of relevant printed materialhave merit.

Regarding obstacles, the survey asked:

Which, if any, of the following are obstacles to you in keepingabreast of new developments in technology by reading? Whichare the one or two you consider most important?

Obstacle Importance

69% I do not have sufficient time to read at work. 48%

47 I do not have sufficient time to read outside of work. 24

27 I keep abreast by ways other than reading. 9

21 Management does not condone reading at work. 11

13 I need a better grasp of mathematics. 6

9 I need a better grasp of science. 5

4 I lack interest in reading. 2

3 Reading wouldn't help in my job. 2

The primary obstacle to adequate reading for keeping up to dateis insufficient time, both at work and outside work. Twice asmany engineers regard the insufficiency of time during work asmore important than that outside work hours. A substantialpercentage uses other methods than reading, which eitherdiminishes the need for reading or competes with it for time. Aslightly lower percentage feels constricted by management andregards this as the third most important obstacle. How many feelconstricted by management is a function of organization level:engineers -23%, leaders -15%, managers -10%. Finally, somefeel the need for a better grasp of math and science; theproportions who do are about the same in each occupationalgroup.

After such a review of the importance of keeping up withtechnological change, the methods used, and sources ofrelevant information, it is important to see how engineers andtheir supervisors stand. How well are they able to remaintechnically viable as they see it?

How would you rate yourself in terms of being up to date with thecurrent state of the art in your technical field? Answer withrespect to other RCA engineers.

I'm in the:Upper 100/aUpper 25%AverageLower 25%Lower 10°/0

Engineers Leaders Managers7% 26% 22%

21 36 3437 31 3623 6 8

11 0 1

Engineers are somewhat pessimistic -only 28% placethemselves above average and 34% place themselves belowaverage. This contrasts sharply with the allocations made byleaders and managers -62% of the leaders and 56% of themanagers place themselves above average and only 6% and 9%locate themselves below. Of course, the question is relative andthe responses are subjective. Still, it can be argued thatengineers have a great deal of almost daily evidence with whichto locate themselves in relation to their colleagues. Theoptimism of leaders and managers cannot be ascribed to a lackof importance of technology at their levels. Question 1 es-tablished that supervisors consider keeping up with newtechnology even more important than do engineers.

Concluding remarksThis survey has measured the need that engineers feel to keepup to date with rapid technological change. It has demonstratedsome of the complexity, variety, and obstacles in doing so.

Technical obsolescence is insidious. There are very fewmileposts to it along the way in an engineer's career, and thosethat do exist are blurred. Many technical people have awakenedone day to the realization that they are behind, sometimesseriously so. Catching up is difficult because the targetcontinues moving at a rapid pace.

The next paper in this series will show what is different aboutengineers who achieve more professionally than others. It willdisclose what these "higher achievers" do to maintain theirtechnical viability. It will demonstrate that the greater utilizationof information sources is strongly related to solving the problemof falling behind.

35

Communication multiplexing

H.E. White

Today's massive communication networksuse multiplexing to provide the economyof scale required to justify marine cables,microwave relay systems, and communi-cation satellites. RCA interests in com-munication multiplexing range from con-cepts to system designs and include anumber of services offered by our threecommon carriers-Globcom, Americom,and Alascom.

Ten years after the first trans -Atlanticcable became operational in 1868, it wasduplexed to allow simultaneoustransmissions in both directions.' Whileduplexing is a special case of multiplexing,it is motivated by the basic need to increaseutilization of expensive communicationcircuits. Another early form of multiplex-ing was the simplex circuit, also known asthe phantom circuit. As shown by Fig. I,the simplex circuit rides piggy -back on twoexisting circuits, but is electrically isolatedfrom them by the balanced transformerwindings at each line termination.

While the early simplex circuits andduplexing increased effective communica-tion capacity, they were not the answer tothe spiraling demand for additional cir-cuits. The first approach to large-scalemultiplexing was space -division multiplex-ing, where many wire pairs are combined toform cables. These are laid between pointsrequiring multiple circuits and are animportant part of present-day communica-tion networks. Space -division multiplex-ing also provides a basis of comparison forother forms of multiplexing, such asfrequency -division and time -division mul-tiplexing.

Recently, though, the effort has movedfrom circuit multiplexing to applying mul-tiplexing to communication networks, es-pecially since the advent of communicationsatellites and low-cost minicomputers andmicroprocessors. The very high cost ofinstalling local circuits that connect sub-scribers to switching centers has also led tomultiplexed subscriber loops that formlocal networks. After a brief review of basic

Communication capacity is being increased by multiplexingentire networks as well as individual circuits.

multiplexing techniques, several examplesof multiplexed communication networkswill be given.

Multiplexing classesThe basic form of multiplexing is spacedivision, which simply bundles many wirepairs into a common cable.

Installation costs and the cost of right-of-way are therefore shared among manycircuits. A problem with space division,aside from the expense and bulk of thecable, is that coupling between circuitsproduces crosstalk between subscribers onseparate circuits. Crosstalk can beminimized by wrapping cable conductorssymmetrically and thus balancing out thecrosstalk currents.

Frequency -division multiplexing, FDM,takes a number of incoming signals andtranslates them to non -overlapping fre-quency bands so they can be transmittedover a single wideband circuit.

FDM was originally thought of as anapplication of wireless techniques tometallic circuits. In 1910, Major George 0.Squire of the Army Signal Corps notedthat the same means of selective frequencygeneration and reception used for wirelesstransmission could also be used to increasethe capacity of existing wire circuits.2Squire's patent, issued in 1911, is quitespecific concerning the means for

generating a plurality of ultrasound fre-quencies, modifying them by a telephonetransmitter, and separating them byreceiver circuits tuned to each of thetransmitter frequencies. This is the basis forpresent-day FDM equipment, which simp-ly translates incoming signals to non -overlapping frequency bands where theymay be transmitted over a single widebandcircuit. At the distant termination of thecircuit, the signals are separated by filtersand translated back to their original fre-quency bands.

Widespread application of frequency -division multiplexing required standardfrequencies and frequency bands, whichwere specified by the FDM hierarchy usedfor long -haul transmission in the BellTelephone System. As shown by Fig. 2, thisdefines the basic message channel (for voicecommunication) as 200 to 3400 Hz andspecifies the basic group as 12 messagechannels with carrier frequencies in the 60 -to -108 -kHz range. The supergroup isdefined as a combination of 5 basic groups,and other higher -order groups are alsodefined. All of the FDM groups are directreplacements for multipair cable, whichwould otherwise be needed in a space -division multiplex system. The FDM signalmay, however, be carried by a singlecoaxial cable, a microwave relay system, ora satellite. None of these carriers would beeconomic for a single message channel, but

CIRCUIT#I

SIMPLEXCIRCUIT

O

CIRCUIT

#2

CIRCU IT#I

SIMPLEXCIRCUIT

0

CIRCUIT#2

Fig. 1Simplex circuit (middle), an early form of multiplexing, rides "piggy -back" on existingcircuits, but is electrically isolated from them.

36

are readily justified when carrying a largeFDM group of channels.

Time -division multiplexing (TDM)came intocommon use with the availability of high-speed switching transistors in the early1960s.

Both the sampling theorem and pulse -codemodulation (PCM) are closely related tothe development of TDM. The samplingtheorem specifies that a band -limited signalof bandwidth B can be exactly reproducedfrom samples taken at a rate of 2B or moresamples per second. Pulse -code modula-tion provides a means of transmitting thesesamples as a string of binary pulses thatmay be regenerated many times as they aretransmitted over circuits employingrepeaters instead of amplifiers. While PCMis not an integral part of TDM, sinceanalog signal samples can be time -divisionmultiplexed, the development of TDM andPCM systems have proceeded together.Aside from their natural compatibility, thishas happened because the Bell Systemcalled for PCM transmission over its TDMhierarchy. Like the FDM hierarchymentioned earlier, the TDM hierarchyspells out the signal groupings that are usedto share the available time of a widebandcommunication circuit. Fixed -time -slotTDM is representedcommutators at each end of the circuit thatsequentially connect a number of signalsources and sinks.

The first level of the TDM hierarchy isknown as T1 carrier. As shown by Fig. 4,T1 operates at a pulse rate of 1.544megabits per second to transmit 24 voicechannels, each sampled 8000 times persecond, in an 8 -bit PCM format. Actuallyonly 7 bits are used for signal information,with the remaining bit used for supervisoryfunctions, so there are 27 or 128 possibleamplitude levels that may be transmitted.In widespread use since 1961, the T1 carrieris used to interconnnect telephone centraloffices from 10 to 25 miles apart. If digitalrepeaters are placed at one -mile intervalsalong the circuit, the TI signal can betransmitted over a metallic circuit thatwould otherwise carry only a singlemessage channel. The capacity of existingcircuits can thus be expanded by 24 timesfor the expense of installing repeaters andterminal equipment. T1 carrier is also abuilding block for higher -order TDMgroups, as illustrated by Fig. 4. Thesegroups are needed to fully load expensivesatellite and microwave transmissionfacilities in much the same way as the FDMequipment mentioned earlier.

Multiplexing applicationsMany multiplexing systems rely on the in-termittent nature of speech.

The above discussion of space -division,frequency -division and time -division mul-tiplexing assumes a point-to-point con -

MESSAGE

CHANNELS

(200-3400Hz)

figuration where many parallel messagechannels are required. A good example is asubmarine cable, which is primarily space -division multiplexed, but each wire pairmay also be frequency- or time -divisionmultiplexed. RCA Global Communi-cations, for example, provides its

2 CHANNELS

60-108 kHz

SUPER

GROUP

BANK

60 CHANNELS312-552 kHz

600 CHANNELS60-2188 kHz OR

x564-3084 kHz

MG2,

MGn

MASTER

GROUP

BANK

FOR

n 2n 3n 6

1200,1800 OR3600 CHANNELS

Fig. 2Frequency -division multiplexing requires a standard hierarchy for combining messagechannels. Individual channels are grouped into channel, group, supergroup, and mastergroups for transmission on one channel. At receiving end, signals are separated by filtersand put back in their original frequency bands.

CIRCUIT

lo -

20

30

4

15

6

CIRCUIT

WIDEBAND CIRCUIT

02

.'0 04

3

5

6

Fig. 3Fixed -time -slot TDM uses rotating commutators at both ends of the circuit to sequentiallyconnect a number of circuits over one channel.

MESSAGECHANNELS

2

3

2

24

CHANNEL

BANK

M12

MUX

L6

T3 612 CHANNEL

46.304 Mb/S

M23

MUX

1

12 96 CHANNEL1

6.312 Mb/S

\s---T1 24 CHANNEL

1544 Mb/S

113

MOO

HUNDREDS

OF Mb/S

THOUSANDS

OF CHANNELS

Fig. 4Time -division multiplexing usually operates with digital pulse -code modulation, althoughanalog TDM is possible. Scheme here starts with 24 voice channels sampled 8000 times persecond, then goes through a number of higher -order groups to combine thousands ofchannels transmitted at megabit/s rates.

37

customers with a capability to frequency -division multiplex one voice channel andup to 5 teletype channels over a singleleased circuit. Other more elaborate mul-tiplexing schemes are also feasible overexpensive cable facilities. One scheme usesthe pauses occurring during a conversationto transmit high-speed data. Since eachspeaker should be listening at least half ofthe time, half of the channel capacityshould be available for data transmission.

The intermittent nature of conversationwas also used by the AT&T TASI3 (TimeAssignment Speech Interpolation) system.Here, another dimension was also used;namely, if many conversations are oc-curring concurrently, there is a highprobability that almost half of the totalcircuit capacity is always available. Thenumber of speakers can therefore be almostdoubled if there is a means provided toshare N channels among M speakers,where M is greater than N. While thecontrol system needed to do this sharing ona statistical basis is not trivial, the originalTASI system was constructed and tested ona trans -Atlantic cable before the availabili-ty of integrated circuits. A new all -digitalversion of TASI is now under test onmicrowave facilities between New Yorkand Boston.4

The concept of sharing channels on astatistical basis has been further refined fordata -communication applications.

Statistical time -division multiplexers thatare an order of magnitude more efficientthan older fixed -time -slot TDMs have beendeveloped for data transmission. Input tothese multiplexers is held in a queue untilcapacity is available on the transmissionchannel. The stored data from one or moreusers is then sent out as a block thatincludes addressing and error -control in-formation. At the receiving terminal, ablock is checked for errors, and, if errorsare found, a retransmission is requested.Following correct reception, the data isdistributed to the addressed users.

The extremely bursty nature of typicalinteractive computer data makes statisticalTDMs very attractive. This was recentlydemonstrated by a system installed forRCA Laboratories, Princeton, N.J., toaccess the corporate computer center inCherry Hill, N.J. A remote concentratorperforms the data collection/ distributionin Princeton; the complementary functionsin Cherry Hill are provided by the front-end processor of the large time-sharedcomputer. This system's ability to detect

SATELLITETRANSPONDER

49

.1 1*-160kHz

CHANNEL 397A

PILOT CHANNEL 3916.(1 FREQUENCY

I_LIItle--36MHz

TRANSPONDER FREQUENCY SPACE

COMMON SIGNALLINGCHANNEL (CSC)

EARTH STATION

/TON ASSIGNMENTS

11121314191 MI ...tCSC TINE SPACE

Fig. 5SPADE multiplexing system Interconnects many earth stations with satellite. Commonsignalling channel (CSC) keeps track of the rest of the message channels as the earthstations use them. In example shown here, earth stations 1 and 3 are communicating overchannel 1. Earth station 1 then broadcasts its unavailability over the CSC and sends itsmessage over channel 1A. Earth station 3 broadcasts its unavailability over the CSC andsends its message on channel 1B. All stations receive the CSC, but station 1 receives 3'smessage on channel 1B and 3 receives 1's message on 1A. After the message is completed,channel 1 is available for whatever earth stations want to use it.

and correct transmission errors andautomatically bypass faulty trunk circuitsappears as important as its improvement intransmission efficiency.

Multiplexed networksStatistical multiplexing's success in point-to-point circuits has led recently toapplications with communication networks.

These include both national and inter-national networks for voice and data andlocal networks for connecting subscriberlocations to a switching center. The com-munication satellite has opened new op-portunities for large-scale networks in-cluding the SPADE systems operated byIntelsat. With SPADE, a satellite's capaci-ty is frequency -division multiplexed amongmany earth stations on a demand basis.One satellite message channel is used by apair of earth stations to complete eachincoming call. After a call is terminated, thesame message channel can be used byanother pair of earth stations to completeanother incoming call. Fig. 5 illustrates thebasic concepts of the SPADE system,showing how the available satellite fre-quency spectrum is divided into messagechannels and a common signaling channel.The signaling channel is used by all earthstations on a TDM basis to keep track ofmessage -channel assignments. When anearth station seizes a message channel, this

information is broadcast during thatstation's time slot on the common signalingchannel. The other earth stations thereforeremove that message channelfrom their list of available channels. In thisway, channel assignments are coordinatedwithout the need for a supervisory controlcenter.

Packet switching is really an extension ofstatistical time -division multiplexing to anetwork.

Here messages, which are really streams ofdigital data, are broken into segmentscalled packets at the originating node of thenetwork. The packets are suitably ad-dressed and then transmitted along the bestavailable path to the destination node. Thepackets corresponding to a particularmessage may travel over different routes,depending on the current loading of cir-cuits and nodes in the network. At eachnode, the packets are checked for errors,and retransmission is requested if errors aredetected. At the destination node, thepackets are assembled in their originalorder and delivered to the recipient.

A packet -switching network willautomatically adapt to changing con-ditions within the network. This includesfailures of trunks or nodes, which may bebypassed by alternate routing, as well asvarying traffic loads from the many con -

38

nected subscribers. The ability to averagethe traffic from many subscribers overmany routes within the network allowshigh utilization of the network resources.This in turn allows usage -sensitive pricing,which is the key advantage of packetswitching to many users. Present packet -switched networks base charges on thenumber of packets transmitted indepen-dent of distance. Simple transactions, suchas querying or updating a data base, whichwere not economic when based on the costof a three -minute phone call, thus becomeeconomic with packet switching. Packetswitching is now being used in the ARPAnet6 and in commercial networks.

The advantages of packet switching will beextended to international data com-munications by the Datel II service to beoffered by RCA Global Communications.The initially circuit -switched Datel IIsystem will provide high-speed (4800 and9600 b/ s) data transmission on a demandbasis. Later expansion will provide a choiceof either circuit or packet switching and acomplete range of synchronous andasynchronous data speeds to match anyapplication.

The desire to reduce communication coststhrough multiplexed networks has reachedthe local distribution areas as well.

Subcriber-loop multiplex equipment hasbeen available to Bell System and indepen-dent telephone companies for the past fewyears.' This equipment operates on a TDMloop network that is shared among sub-scribers connected to the loop. Suchsystems are particularly valuable in ruralareas where the cost of installing andmaintaining long local loops is high.

COMPUTER

TERMINAL

ORCOMMUNICATION

INTERFACE

Hugh White has been with the Com-munications Research Laboratory at RCALaboratories since 1961. He was a memberof the PANGLOSS project and contributedto the design and analysis of com-munications systems techniques for theNavy's Special Projects Office. He alsoworked on redundancy -reduction tech-niques for storing and transmitting imagedata. More recently he has worked oncomputer -to -computer data com-munications, including the design of aninternal data network used at RCALaboratories.Contact him at:Communications Research LaboratoryRCA LaboratoriesPrinceton, N.J.Ext. 2168

The principle of the TDM loop network isthe basis for the Data Loop Exchange(DLX) System8 used for internal datadistribution at RCA Laboratories. In thiscase, the TDM loop network avoids themulticonductor cable and central dataswitch required by a space -division system.All subscribers are connected to the singletwisted -pair loop network shown in Fig. 6.Since DLX divides the loop capacity into32 TDM channels, up to 32 pairs ofsubscribers can communicatesimultaneously. Actually, many more than64 subscribers can be serviced by DLXbecause channel access is on a demandbasis and inactive subscribers do not re-quire loop capacity. In comparison to localtelephone service normally used for datadistribution, DLX provides higher datarates, lower error probabilities, and sub-stantially lower costs. The cost advantagehas become particularly evident becauselocal telephone service is charged on a

COMMUNICATION

INTERFACE

COMPUTER

OR

TERMINAL

1.536 Mb/S32 CHANNEL TOM

COMMUNICAT 10

INTERFACE

COMPUTER

OR

TERMINAL

Fig. 6Multiplexed local data loop is used for internal data exchange at RCA Laboratories.Alternative configuration would require separate cabling setups between all of thecommunicating locations.

message -unit basis. The DLX system willbe manufactured and marketed by an RCAlicensee to customers with local data com-munication requirements.

Future trendsAdvances in communication multiplexingwill be related to the continued develop-ment of large-scale communicationnetworks. These networks will permitresource sharing among many subscriberson a statistical basis and will include thelatest computer and microprocessor -basedtechnology. They will lower communica-tion costs and thereby make newcommunication -related serviceseconomical, and these in turn will increasethe demand for additional com-munications. This trend will require con-tinuing innovations by communicationssuppliers; their ability to meet this demandwill determine their competitive position inthe marketplace.

ReferencesI. Finn, Bernard S.; "Growing pains at the crossroads of the

world; a submarine cable station in the 1870's," Proc. of theIEEE, Vol. 64, No. 9 (Sep 1976) pp. 1287-1292.

2. Squire, George 0.; Multiplex Telephony and Telegraphy,Government Printing Office, Washington, 1919.

3. Fraser, J.M.; Bullock, D.B.; and Long, H.G.; "Overallcharacteristics of a TASI system," Bell System Tech. J., Vol.51 (Jul 1962), pp. 1439-1454.

4. Institute of Electrical and Electronic Engineers, Spectrum,Vol. 13, No. 8 (Aug 1976) p. 65.

5. Werth, A.M.; "SPADE: A PCM FDMA demand assignmentsystem for satellite communications," Conf Record, 1970 Int.Conf. on Communications, pp. 46-22.

6. Roberts, L. and Wessler, B.; "Computer network developmentto achieve resource sharing," Proc. of SJCC, Vol. 36, AFI PSPress, pp. 543-549.

7. Boxall, F.S.; "A digital carrier concentrator system with elastictraffic capacity," Conf. Record, 1974 Intl. Conf. on Com-munications, pp. 24B -1-24B4.

8. White, H.E. and Maxemchuk, N.F.; "An experimental TOMdata loop exchange," Conf. Record, 1974 Intl. Conf. onCommunications , pp. 7A -1-7A-4.

Reprint RE -23-3-3Final manuscript received March 30, 1977.

39

Military communications review and survey

J.L. Santoro) J.B. Howe The trend is toward all -digital satellite links that providebetter security, increased survivability, higher reliability, andmore capacity.

Military communications networks range in type fromstandard voice -grade telephone systems to complex datalinks controlling missiles or remotely piloted vehicles viasatellite. Collectively, these networks join our militarycommand and control systems through a kind of globalnervous system, delivering intelligence and surveillanceinformation to the National Command Authority and con-trol information to the forces.

Paradoxically, such communications are likely to be dis-rupted when most needed, since the elements of the systemare widely dispersed, often on a global basis, and are thusdifficult to defend. The continuing challenge is, therefore,to increase the survivability of the communications links tokeep pace with developments in weapons and deploymentof forces.

From the viewpoint of today's communication systemdesigner, probably the most important tasks, beyond thecontinuing effort to improve reliability and data rates, are:

increase hardening to avoid outages in a nuclear war. improve security to evade interdiction and spoofing.*

*In this context, interdiction means that an enemy could interceptand understand information in our communication system;spoofing means that an enemy could insert false information intoour system and deceive us into thinking the information is valid.

Defense CommSystem(DCS)

Common UserNetworks -1

High freq (HF) andtropo

Defense Satellite CommSystem (OCAS)

AutodinAutovonAutosevocom

add anti -jam capability to overcome electroniccountermeasures. convert to all -digital transmission, which offers severalinherent advantages-im proved quality, increasedsecurity, and standard methods for handling voice anddata.

This paper surveys the significant present and futuremilitary communications networks that have been, and arebeing, developed in response to these pressures.

In general, any military communications system can beidentified as either a common -user network or a dedicatednetwork. Ideally, they should all be standardized, common -user types, but special strategic or tactical field re-quirements give rise to networks dedicated to a specialfunction. (See Fig. 1.)

Fig. 1Basic military communications structure. The structure shown waschosen partly for this paper and partly because the networks havereally emerged this way in response to global strategic andwidespread tactical problems.

MilitaryCommunications

Tri ServiceTactical(TriTac)

Theatre of operationsswitched network

Nodes within thenetwork

Transmission linksconnecting the nodes

Mobile access tothe Network

Transitionconfigurations

DedicatedI- Networks -I

TacticalSystems

Army combat radiosTactical satellitesShipborne communicationsJoint Tactical

Information Distribu-tion System (MOS]

StrategicSystems

SeafarerSatellitesHF

Satin VVLF/LFTacamo

DCS is the "in -place" worldwide system that serves as thefoundation for emergency communications while con-currently satisfying normal peacetime needs.

The Defense Communications System (DCS) carriescommon -user traffic and extends command and controlcapability throughout the U.S., Europe, and the Pacific; thetypical elements of the DCS network are shown in Fig. 2.The DCS uses practically every variety of transmissionmedia, from cable to communication satellites. While 62%of these facilities are leased from commercial commoncarriers (e.g., AT&T, RCA, Western Union), thegovernment -owned portion represents an investment ofabout $3 billion. The government owns and operates only asmall part of the cable net used for DCS, but owns andoperates a substantial number of radio links, especiallyoverseas.

While the current network is based larg9ly on the standardanalog 4 -kHz telephone channel, the move towards digitaltransmission is accelerating, for several reasons:

Digital circuits are amenable to LSI technology, whichgenerally results in lower -cost, more -reliable equipment. Digital transmissions can be secured by cryptographictechniques. Digital signals can be reconstituted at appropriate relaypoints providing better quality for long -haultransmissions.

Dependence on high frequency (hf) links is diminishing.A number of hf links provide long-distance com-munications, carrying one voice channel or a modestnumber of teletype or low -speed data channels. Variationsin the ionosphere cause relatively poor availability (95-99%)and unpredictable outages in even the best -engineered hflinks with adequate frequency assignments. The fadingcharacteristics of the medium, especially the selectivefading resulting from multipath transmission, results inrelatively high error rates on digital circuits. As a conse-quence, hf links are being phased out in favor of satellitesystems wherever possible. In some cases, hf links will beretained as back-ups to other facilities to reducevulnerability of the total transmission system.

MilitaryCommunications

Common OurI- Networks

Defense Comm

System(SCSI

Nigh Imp INFI endtrope

Oelense Satellite Comm

System IOCASIAulodinOutmanAuloseyncom

Troposcatter and line -of -sight communications systemsare also being replaced by satellite links.The bulk of the non -satellite facilities in the government -owned portions of the DCS are multichannel radio -relaysystems, either line -of -sight (LOS) operating in the 4- and8-GHz frequency bands or tropospheric -scatter (tropo)links operating in the 1-, 2-, and 4-GHz frequency -bands.Most of the existing radio relays use frequency divisionmulitplex (FDM) to handle the standard analog channels.However, FDM is being replaced by digital transmissionwith new digital modems capable of data rates ranging from24 kb/s, for what is termed narrowband, to multi Mb/s forwideband multichannel trunking.

While the military's reliance on line -of -sight and

troposcatter channels is diminishing as DCS satellitecapability increases, some of these facilities will beretained, as in the case of hf, for added survivability throughredundancy. Also, line -of -sight microwave links will beused increasingly to connect users and the satellite earthstations. The military will probably also exploit the higherfrequencies (above 10 GHz).

Defense Satellite Communications System (DSCS) use isincreasing.

The DSCS continues to be a major customer for satellitechannels from commercial carriers, and transmission overmilitary -owned and operated facilities has been increasingdramatically. The first satellite for the Defense SatelliteCommunications System-Phase II (DSCS-II) waslaunched in 1971. Currently, two geostationary satellites,one over the Atlantic and the other over the Pacific,operating in the 7 to 8 GHz region, handle military trai:'.?..

Reprint RE -23-3-6Final manuscript received November 8, 1977.

TO

ASMARA

BANGKOK

FUCHO/TOKYO

PHILIPPINES GUAM

NEW GUINEA

WOOMERA o -

A BAK

NE;i ZEALAND

ALASKA

RCA ALASCOM TROPO MICROWAVE SATELLITE

CAPE LISBURNE0

ELMENOORF

L/C6N o HAINES

KODIAK '.KETCHIKAN

ss,

VICTORIAsi, PORT ANGELES

i POINT ARENA

PALO ALTO

HAWAII

PSTOCKTON

. SAN LUIS

GANADA

CANADIAN COML. TROf'0. CANADIAN COML. MIN, VE MILITARY TROPO SATELLITE

FORTOBISPO LEAVENWOR1 H

UNITED STATES

AUTODIN AUTOVON LEASED CIRCUIT SATELLITE

Fig. 2Defense Communications System (DCS). This common -user system comprises about 42 million miles of varioustypes of circuits (cable, satellite, microwave, etc.) that go to over 1000 locations in 70 different countries.

Earth stations of varying capability have beenprocured to provide service at 7 to 8 GHz. Thelarger terminals require carefully prepared largesites and are considered semipermanent in-stallations. They are designed to handle largenumbers of channels, are useful in safe areas, andneed not be relocated often. To satisfy the needsof smaller, more vulnerable users, a family oftruck -transportable terminals has beendeveloped. These terminals are mounted in

shelters for 11/2 ton or 21/2 ton truck transport. Eachterminal is self contained and can provide fullcommunications capability less than one hourafter arrival at its site.* RCA has a contract forinitial production of several terminal con-figurations for different channel capabilities.Other fixed, shipborne, and airborne stations arealso being considered by the military.

*This program was described in Volume 22, No. 1 of the ACA Engineer byTyree, et al, in "Small shf satellite ground terminal developments."

42

LAKEHURST

HINGTON

THULE

III

11'1

I

CAPE DYERKEFLAVIK

N

\ MORMON° HILL

FYLINGOALEBERLIN

LONDONDERRY -.°3 \WOODBRIDGE #,/

NEW FOUNDLAND ---p 42:42)1'111MASENS

LISBON' RULATUCKERTON

BERMUDA

0

FLOBECO

=4B0.0 SIDI YANIA

CAPE VERDE

\ASCENSION

NAPLES

s CAPETOWN

The government has recently started develop-ment of DSCS-III to further improve com-munications for command and control of ourmilitary forces. DSCS-III will carry sixtransponders, and its designers are consideringthe use of two independent multibeam downlinkantennas, with patterns variable from 3.5° to fullearth coverage. Existing ground terminals will beused. While DSCS-III is primarily for extension of

EUROPE

HF RADIO MICROWAVE AUTODIN AUTOVON SATELLITE TROPO

ASMARA

PESHAWAR

DIYARBIKAR

TO

BANGKOK

TYPICAL DCS GOVERNMENT OWNEDAND

COMMERCIAL LEASED CIRCUITS

SUBMERGED CABLES

TROPOSPHERIC RADIO

DSCS SATELLITE

HF RADIO

X01

current capabilities, the influence of digital trafficon military systems will likely cause a trend totime -division multiple -access (TDMA), anddemand -assigned multiple access (DAMA)techniques to further increase system flexibilityand capacity. Other changes, which include newspecial-purpose modems, can be expected todecrease the vulnerability of the satellites tojamming.

43

0 PAC

( )0

EXISTING AUTODIN

C & C SITES

Fig. 3AUTODIN is the DCS common -user data communication networkfor the continental U.S. and Hawaii.

Within the DCS, AUTODIN is the common -user data -communications system for the continental U.S. andoverseas DOD subscribers.

AUTODIN is a message -switching store -and -forwardservice with nine switching centers in the U.S. and Hawaiiand six centers overseas. (See Fig. 3.) In the U.S., WesternUnion is the system manager, and RCA supplied theswitching equipment. A typical AUTODIN switching centerincludes controls, modems, and switches. The centers areconnected, for the most part, by leased cable andmicrowave facilities.

The primary function of the AUTODIN I system is to deliverdata messages from any terminal to any other terminal inthe network. The system normally operates on a first -in,first -out basis but allows high -priority messages to takeprecedence.

The system handles about 600,000 messages (averaging2000 characters/message) per day. Approximately 1400terminals use the switches, with approximately 1150 in theContinental U.S./Hawaii areas, and the remainder in

various international locations. Most traffic is narrative orrecord, which in general is message -structured, and doesnot require high-speed response.

Packet switching will be used on AUTODIN II.

AUTODIN II is a new development to accommodate thehigh speed response requirements of interactive sub-scribers, where terminal and computer response times maybe much faster than AUTODIN I. This system will accom-modate computer data -base transfers, as well as recordtraffic.

The approach is to send packets of data constituting eithera small part of a message or the total transaction, as distinctfrom AUTODIN I where an entire message is collectedbefore being routed through the network. Therefore, packettraffic of small transactions can be routed as soon asaccepted by the originating packet switch as a bursttransmission. AUTODIN I traffic will eventually be phasedinto AUTODIN II.

AUTOVON is the common -user telephone network thatconstitutes the backbone voice network for the DCS.

AUTOVON contains fifty-nine automatic switches in theU.S. and Canada, twelve automatic switches overseas, andhas approximately 300,000 subscribers. It offers basicallystandard analog telephone service or priority service forcommand -control subscribers. In the U.S., the switchingcenters are connected by leased facilities with the inherentredundancy of the AT&T networks providing automaticalternate routing. The overseas DCS-owned environmentresults in a thinner connectivity.

In addition to the basic voice service, AUTOVON transmis-sion facilities often act as backbone trunks for the DCS datacircuits on a patched basis.

The AUTOSEVOCOM system provides secure voicechannels for higher priority users located both in the U.S.and overseas.

The AUTOSEVOCOM (automatic secure voice com-munications) system presently consists of severalautomatic and manual switchboards to provide securevoice links for approximately 14,000 users. It can useexisting trunking facilities to handle narrowband digitizedvoice (2.4 kb/s and 9.6 kb/s). It also provides high -qualitywideband digitized voice (50 kb/s) over satellite and limitedterrestrial trunking connecting local enclaves. TheAUTOSEVOCOM system is predominantly a government -owned and -operated network.

Plans are now underway to upgrade the system in what iscommonly called AUTOSEVOCOM, Phase II. This systemwill provide a more widespread capacity for digital securevoice channels with better quality for the 2.4 kb/s users andwill standardize on 16 kb/s for the wideband users. Thepresent concept is to use upgraded telephone companyswitches in the U.S. and the newly developed TTC-39 circuitswitch for the overseas network. A new digital -accessexchange switch is being developed to service localsubscribers and act as the junction point to access the maintrunking network.

MilitaryCommunications

Common UserNetworks -I

Tri ServiceTacticaliTriTac)

Theatre of operationsswitched network

Nodes within thenetwork

Transmission linksconnecting the nodes

Mobile access tothe Network

Transitioncontinuations

The Army, Air Force, and Navy have individual andcollective responsibilities for defending national security.These "tactical" responsibilities cover a number of potential

44

Fig. 4Typical connectivity model for common -user tri-service tactical communications network.The composite network will service both area and command and control communications.Primary nodes serve the theater of operations headquarters. Austere major nodes and minornodes are located closer to the battle area.

scenarios ranging from a "show of force" in the Middle East to large-scale combatas in Vietnam and Korea. For land operations, tactical Army and Air Forceelements are generally assigned to a joint task force or theater -of -operations. Foramphibious assaults, Marine Corps ground and air elements are assigned to anintegrated marine amphibious force.

Looking to 1985 and beyond, "common -user" communications equipments forthese types of tactical missions will be provided under the Tri-Tac program. Thefollowing paragraphs discuss the individual and collective roles of various tacticalcommunications systems covered under the Tri-Tac program.

The theater -of -operations switched network has its primary node at head-quarters.

The joint theater -of -operations network is organized as shown in Fig. 4. Majortheater headquarters is serviced by the primary node, while tactical units closer tothe battle area are serviced by the austere major nodes and minor nodes. Thenodes can be located at the base or in the field, depending upon the tacticalsituation.

Each node in the network provides trunking connections and also serves as thenetwork access point for both switched and dedicated user circuits. The conceptillustrated in Fig. 4 projects a mature system in which radio communications alsoincluaes satellite terminals. The backbone of each major node is the 300- to 600 -line AN/TTC-39 circuit and message switch presently under development. Theaustere major nodes will use a smaller switch, the AN/TTC-42, providing 75 to 100lines. Tactical units (minor nodes) will use a 30 -to 90 -line switch, the SB-3865, forlocal and access switching.

Superimposed on this theater -of -operations switched network is the TacticalCommunications Control Facility (TCCF), which is set up to handle systemplanning, system control, individual node control, equipment support, andsatellite communications control.

Tri-Tac plans for post -1985 satellite communications are based on use ofdemand -assigned time -division multiple access (DA-TDMA) techniques.

Satellites are inherently limited in the number of simultaneous voice channels (orequivalent data channels) that can be transmitted. Current operation

is limited by control and switchingtechnology to dedicated channelassignments. Each network terminal isassigned a fixed number of channelsbased on the estimated traffic re-quirements limited by the total satellitecapacity. Individual terminals may,therefore, instantaneously require morechannels than they have been assignedwhile other terminals are using less thanassigned.

Demand -assigned operation allows,through a control/assignment techni-que, the assignment of individualchannels to each terminal as required.This arrangement requires a controlterminal to have knowledge of thecurrent status of all channels and to beable to assign an unused channel uponrequest to a network terminal. Such anoperational approach allows thenetwork to make maximum use of thesatellite channels based upon the instan-taneous channel requirements of theindividual network terminals.

In the Tri-Tac plan, a primary masterterminal will be designated to controlsystem access while other terminals aredesignated as alternate masters. Theactive "master" terminal will generateframe -synchronization reference bursts;generate and distribute special networkcontrol and status information; andmonitor and report subsystem perfor-mance. The DA-TDMA satellite com-munications system, however, will notdepend entirely on the master terminalstation; each terminal will have an inter-nal processor that will perform all criticalfunctions in real-time, independent ofthe monitor center.

The nodes will be connected by shfsatellite communications; single andmultihop LOS relay in the vhf, uhf, andshf bands; and single and multihoptroposcatter at shf.

The terminals used in the demand -assigned (DA-TDMA) satellite systemcan generally be located within the nodalperimeters since they do not have thesiting constraints of terrestrial -linkterminals. Such terminals will be selfcontained; i.e., they will include all call -processing, preemption routing, andcontrol functions required to set updemand -assigned channels betweensatellite terminals in cooperation withthe associated Tri-Tac switchingfacilities.

45

LOCALTELEPHONE

SUBSCRIBERS

MOBILESUBSCRIBER

TERMINAL (MST)

TRUNKS

CENTRALSWITCH

OFNODE

NETRADIO

INTERFACE

MOBILESUBSCRIBER

CENTRAL

Fig. 5Mobile subscriber access subsystem. A mobile subscriber can use the Mobile Subscriber Terminal (MST) tocommunicate directly with fixed or mobile units.

Thus, the satellite subsystem will appear to be transparentto the switching subsystem and, except for satellite -linkpropagation delays, will impose no unique constraints onother Tri-Tac system elements. In addition to the demand -assigned circuits, the satellite subsystem will be able toaccommodate sole -user circuits of preassigned channelsby establishing non-preemptable connections betweenterminal pairs.

The multichannel terrestrial radio terminals associated witha major node may be located 6 to 10 km from the node in anarea designated the "radio park."

The Mobile Access Program will extend the tacticalswitched system to mobile telephone subscribers.

The Mobile Access Program integrates the functions oftelephones, telephone switching, radio transmission, com-munications security, radio -wire integration, and controlfor mobile subscribers. This requires a family of mobilesubscriber equipments arranged typically as shown in Fig.5. A mobile subscriber equipped with a Mobile SubscriberTerminal (MST) can communicate directly with other fixedor mobile users on the network via the Mobile SubscriberCentral. Radios of the SINCGARS variety (described later)will be capable of accessing the network via the Net RadioInterface.

As in DCS, the transition is to an all -digital system.

The preceding paragraphs have provided some insight intothe architecture and equipments being developed fortactical communications systems under the Tri-Tacprogram. The transition from current tactical equipmentinventories to the mature Tri-Tac posture will beevolutionary. While each service has its own plans for thistransition, the following sequence will generally apply:

1) The initial systems deployed will consist of hybridanalog and digital switching equipments serving analogand digital subscriber terminals with wideband digitaltransmission links.2) Later phases will approach (asymptotically) an all -digital system by phase -in of digital subscriber terminalsand digital switching capacity and phase -out of analogterminals and switches.

MilitaryCommunications

Common User Dedicatedr-- Networks -1 r- Networks -IDelensa Comm Tri Service

System Tactical Tactical StrategicINCSI (Trifle{ Systems System

High tray (tin and Theatre al operations Army combat radios Seafarertrope switched network Tactical satellites Satellites

Sefeme Satellite Comm Noyes within the Shipborne communications SF

System INCAS) network Joint Tactical Satin VAulailin Transmission links Information Distribu VliffleAutovon connecting the nodes Non System I.ITIOSI TamaAutosevocom Mobile access to

the NetworkTransition

cenlIgurettens

Dedicated TacticalAll military forces have the common problem of providingsecure and reliable communications among mobileelements (ships, airplanes, ground vehicles, people)deployed in a given area of operations. The uhf band hasbeen the most common for line -of -sight communicationsbetween aircraft and ground elements. For ground mobileelements, the Army has relied on vhf because of its betterpropagation characteristics in the types of terrain andantenna elevations unique to ground mobile com-munications. The Navy has relied on hf for non -line -of -sightfleet communications.

Generally, in the past, the military has survived withoutsecurity or electronic counter -countermeasures in the

46

Vehicular

Commontransceiver

Manpack

Aircraft

Fig. 6This RCA -developed transceiver, the AN/URC-78, can be carried by foot -soldier ormounted in a jeep or aircraft.

tactical environment. However, recent experiences havedemonstrated that more sophisticated measures areneeded in the future. While these systems are classified asdedicated because of the specific environments in whichthey must operate, they are not totally divorced fromproblems of interoperability and must be built to interfacewith the Tri-Tac systems.

Some of the more advanced systems in operation today orunder development to solve the problems inherent in thetactical arena are described in the following paragraphs.

Combat radios are becoming more important as combatbecomes more mobile.Warfare has become increasingly mobile; thus, commandand control of the Army combat forces depends more andmore on radio communications to replace the traditionalwire -tie systems. Radios are carried by infantrymen, aremounted in military vehicles, and are carried aloft in thesupporting Army aircraft. All these elements must com-municate among themselves and with higher commandauthorities. For this mobile operation, the Armz primarilyuses fm radios in the lower part of the vhf region (30 to 80MHz). Some radios in the hf and uhf portions of thespectrum are also used for special applications.

In general, the combat radios are used to establish netsconnecting each commander with his subordinate com-mands. The required range varies from one or twokilometers for the lower echelons up to forty kilometers ormore for higher echelons.

More than ten years ago, the Army recognized the need todevelop a new family of combat radios to

improve spectrum use; enhance communications security; reduce vulnerability to enemy intercept, jamming, anddeception; increase operating life; and ease logistic support.

RCA used the AN/URC-78 type modulesto produce a manpack radio (above) thatincludes a capability for a frequency -hopping anti -jam mode.

To achieve these goals, the Army initiated a number ofsystems studies and advanced development programs. Oneof these programs produced the AN/URC-78, an RCA -developed transceiver about half the size and with longerlife than the AN/PRC-77, the present standard radio. Animportant feature of this development is that the basictransceiver can be used as the central element in vehicularor airborne systems, as shown in Fig. 6. RCA subsequentlyused the AN/URC-78 type modules to develop anddemonstrate a combat radio that included a frequency -hopping anti -jam mode.

The Army is now proceeding with the development of aSingle Channel Ground Air Radio System (SINCGARS) atvhf, which is based on the results of these systems studiesand advanced development programs.

Many of the communications requirements of the tacticalusers could be satisfied more effectively if they could takeadvantage of satellite communications.

The backbone multichannel transmission to and from fieldforces can be handled by shf satellites, analogously to theDCS. In fact, the small terminals described earlier areplanned for use by the Army and Air Force. Other terminalequipments have been designed for large naval vessels.However, the size and cost of such terminals exclude manyusers at the present time who need such a capability. Theseusers are typically small, mobile, and numerous, with arelatively small communications demand.

For such users, satellite communications must be at lowerfrequencies, where small, lower -cost equipment becomespractical. The military uhf band (225 to 400 MHz) wasselected for this type of service. Initial experiments usingthe M.I.T. Lincoln Laboratory Experimental Satellitesdemonstrated the feasibility of uhf satellite com-munications for small mobile platforms, including aircraft,ships, and land vehicles. Later experiments under the joint -forces TacSatCom program, which incorporates both uhfand shf capabilities, also demonstrated this capability.

47

_

What is RCA's role?

I

RCA has been a major supplier of military com-munications equipment, systems, and studies virtuallysince RCA started manufacturing radio equipment inthe early 1930s. Much of the work at GovernmentCommunications Systems is classified, and thereforecannot be mentioned here. However, the militarycommunications systems listed below have all beendeveloped by RCA, and provide some measure of ourinvolvement.

HF RadiosAN/ARC-21AN/ARC-65AN/ARC-142AN/ARC-161AN/URC-88AN/ARC-170AN/ARC-185

Line -of -sight and troposcatter linksAN/GRC-50AN/TRC-97AN/TRC-97A

SHF satellite communications terminalsAN/TSC-85(V)2AN/TSC-93AN/TSC-94AN/TSC-86( )

Strategic systemsMinuteman SCNSanguineIntegrated radio room (IR') for Trident

Switching systemsAUDODIN IAUTOSEVOCOMIntegrated Circuit & Message Switch (ICMS)Integrated Voice Communication System (IVCS)Automatic Data Processing-Telecommunications(ADPT)

UHF radiosAN/ARC-34AN/ARR-69Time Division Data LinkAN/ARC-143AN/ARC-143B (LOS & SatCom)

Army combat radiosLAN/PRC-8, 9, 10

AN/PRC-25AN/PRC-77AN/URC-78

As a result of these experimental programs, the military hasprocured the FltSatCom satellite, which is scheduled fororbital operation in late 1977. This bird will carry repeatersfor both the Navy Fleet Satellite Communications (FltSat-Corn) System and the Air Force Satellite Communications(AFSatCom) System. User terminal equipment for thesesystems has also been developed. The Navy is presentlyusing uhf repeaters aboard the Maritime Satellite (MariSat)while waiting for FltSatCom to become operational.

The trends one may expect in this area in the future aresimilar to those for shf satellites:

transition toward all -digital secure transmission; provision of antenna nulling and signal processing inthe satellite to provide anti -jam capabilities; and demodulation and time -division multiple access andswitching in the satellite to interconnect various uhf nets,uhf and shf users, broadcast transmissions, and con-ference calls.

With each new satellite system success, the demand forsatellite channels will increase. The vulnerability of thesatellite, however, both to jamming and to physical attack,will require that the other tactical communications modesbe retained.

Shipborne communications are changing in response totactical needs.

The Navy Tactical Data System (NTDS) was developed inresponse to the complex high-speed problems of directinga Naval task force in modern tactical combat. The systemuses hf and uhf links to transfer important voice and datacommunications among ships in a task force via a pollingscheme controlled by a master ship equipped with com-puters and displays.

The Common -User Digital Information Exchange Sub-system (CUDIXS) and the Submarine Satellite InformationExchange Subsystem (SSIXS) are link -control subsystemsof the Navy's Fleet Satellite Communications (FltSatCom)program and are designed to speed the exchange ofmessages between ships at sea and shore -based stations.FltSatCom will afford more reliable communications over amuch larger area than does the present hf system used bythe Navy. The better quality (i.e., greater bandwidth, less"noisy") circuits provided can also permit signaling at ahigh transmission rate for the same or a lower error rate. Asatellite channel can therefore permit one shore -basedstation to serve a large geographic area and, by time-sharing the use of the channel and signaling at a high rate,serve a much larger population of users.

New developments are underway to include anti -jam andlow -probability -of -intercept capabilities.

The Joint Tactical Information Distribution System (JTIDS)is a secure information exchange.

Over the past 20 years, the military services have sought todevelop a flexible jam -resistant secure digital informationsystem to include location and identification information.

48

This effort culminated recently in theJoint Tactical Information DistributionSystem (JTIDS) program. The firstphase of the program will be aimedsimply at developing a system to dis-tribute information in support of tacticalmissions. The second phase will includeresearch and development to expand theinformation distribution capabilities andto add the location and identificationfunctions to the system.

Basically, the JTIDS net serves as aninformation bus, where each user canselect the specific information requiredfor his part of the mission from the total.Thus, each user transmits importantmission information to the bus, andreceives only that portion of it requiredfor his part of the mission. Some usersmay be largely information suppliers(e.g., forward air controllers, sur-veillance radars), others may beprincipally users (e.g., tactical aircraft,SAM sites), while still others (e.g.,tactical air control centers) may both useand provide substantial information tothe bus.

The basic element of JTIDS is a singlesecure time -division net, with time slotsallocated among the users in accor-dance with their needs. The time -slotconcept is illustrated in Fig. 7. Thesystem is designed with all necessarycontrol logic at the user terminal, allow-ing the net to be controlled from anystation. Each time slot contains a syn-chronization burst, the transmitted infor-mation, and a guard period. The in-dividual bursts employ spread -spectrumtechniques and error -correction coding,to afford protection against jamming.JTIDS operates from 962 to 1215 MHz, aband currently occupied by the locationand identification systems TACAN andIFF. However, the JTIDS signal designpermits compatible operation with thoseother services. The range of the net canbe extended beyond line -of -sight byaircraft relay, and the relay function canbe assumed by any terminal.

The basic technology required to imple-ment JTIDS exists, and rapid advancesin solid state technology, in particular,make such a system feasible for manyapplications. However, there remains asignificant challenge to drive the costand size down to a sufficiently low levelthat more universal use becomeseconomically and operationally at-tractive.

Jack Santoro, as Manager of SystemsEngineering, is responsible for militarysystem development for Government Com-munications Systems.Contact him at:Systems EngineeringGovernment Communication SystemsGovernment Systems DivisionCamden, N.J.Ext. PC -3117

Joe Howe, as Chief Engineer for Govern-ment Communications Systems, directsRCA's design and development efforts onmilitary communications equipment.Contact him at:EngineeringGovernment Communications SystemsGovernment Systems DivisionCamden, N.J.Ext. PC -2646

Fig. 7JTIDS data bus concept. Timeslots are allocated to users based on need.

49

AFSAT

SAC

BOMBERS

VLF

Fig. 9Typical strategic communications network.

NATIONAL COMMANDAUTHORITY

NATIONAL EMERGENCYAIRBORNE COMMAND POST

ADVANCED AIRBORNECOMMAND POST

NATIONAL MILITARYCOMMAND CENTER

-

ALTERNATE NMCC

SEAFARERAFSAT/FLTSATSATIN VHF

VLF/LFTACAMO

NEACP

HF

-74

FLEET BALLISTIC MISSILES

INTERCONTINENTAL BALLISTIC MISSILES

Fig. 8These dedicated stratetic systems connect the National Command Authority withweapons systems and forces.

FORCES

AUTODINAUTOVONAUTOSEVOCOMTERRESTRIALSATIN IV

SAC BOMBERS

DSCS

HF

MilitaryCommunications

Common Use.r- Networks -IDefense Cumin Tri Service

-DedicatedN

System Tactical Tactical Strategiclop] (Trani Systems Systems

High free [NEI and Theatre al operations Army combat radios Seafarertrope switched network Tactical satellites Satellites

Defense Satellite Comm Nodes within the Shipborne communications HF

System IOCASI network Joint Testiest Satin VAutodin Transmission links Informetion OistrIbui VliF/LFAIMPIOP connecting the nodes fin System ijItOSI TacomaAutosevecom Mobile access to

the NetworkTransition

configurations

Dedicated strategicsystemsStrategic networks assure communicationsbetween the National Command Authorities(NCA), the Joint Chiefs of Staff, and thecommanders who need to execute integratedoperational plans and other time sensitiveoperations. These systems allow the NCA togo directly to the forces as well as to the

BASES unified and specified commanders as shownin Fig. 8. A discussion of these dedicatedstategic systems would be too lengthy for thispaper, since they are so many and so varied.For completeness, however, several typicalstrategic systems are listed below:

The National Emergency Airborne Com-mand Post (NEACP) that can remain air-borne over the U.S. for long periods of time,providing survivable communications withthe other strategic networks.

The Advanced Airborne Command Post(AABNCP) is an extension of NEACP usinga 747 aircraft for expanded capability.

50

SAC

BOMBERS

.0.

0

AFSAT II/FLTSAT

SURVSAT

CRUISE

MISSILES

44/BASES

Fig. 10For the future, the strategic communications network presents a changing picture, with primary emphasis on survivability.

The Seafarer system (formerly Sanguine) that will provide(if implemented) survivable long range communicationsvia extremely low frequency buried transmitters. Theburied antennas will extend over large land areas.

The Satin IV system for the Strategic Air Command (SAC)will be a totally automated data communications networklinking SAC bases with each other and with missile sites.

The very low frequency system, both ground based andairborne, will deliver messages to strategic elements on aglobal basis.

Satellites and hf radio have obvious strategic applications.

The dedicated strategic systems will be interwoven into theAUTODIN, AUTOVON, and AUTOSEVOCOM types ofcommon -user nets to use the redundant connectivityprovided by them.

These dedicated systems are illustrated in Figs. 9 and 10and are part of what is known as the World Wide MilitaryCommand and Control Systems (WWMCCS).

Concluding remarksAll -digital communications systems are the wave of thefuture. Three reasons are:

Cost: With the standard LSI packages proliferating, digitalequipment becomes less expensive to buy and to main-

tain. Digital systems also have inherently more capacityper channel and thus are less expensive to operate.

Performance: Total link performance is independent ofdistance since digital signals can be regenerated as oftenas necessary; noise and distortion in an analog systemare cumulative. Furthermore, digital systems can handlevoice, facsimile, teletype, and computer data in a singletransmission.

Security: This growing military need is more easilysatisfied with a common digital standard.

For these reasons, the military communications users arereplacing their analog systems with digital ones. Thechangeover is evolutionary. Thus, for a considerable periodof time, older analog systems will coexist with digital ones.However, since operating in this transition is costly-morecostly than all -digital or all -analog operation-we canexpect the military to move to digital systems as fast asjudiciously possible.

Survivability of our communications in the case of nuclearweapons effects or electronic countermeasures is becom-ing increasingly important. This is very costly to achieve,but new technology now available will allow more rapidgrowth in this area also. Again, it will be an evolutionaryprocess.

51

Computer optimization producesa high -efficiency 4-GHz MESFET linear amplifierF.N. H.C. Huang

Many communication systems rely onsaturated microwave amplifiers for highoutput power and high efficiency, whichare particularly beneficial in satellite com-munication systems. Yet, it is becomingclear that linear microwave amplification isdesirable for satellite systems so they canoperate with multiple carriers in a single rfchannel. The high linearity of such a systemgenerates a low intermodulation, or, inother words, a low interference between thecarriers. Each carrier might be generatedby a simple small earth station. Thus, manyearth stations can access the transponderdirectly without a large multiplexingnetwork on the ground and without a largeearth station for wideband large -capacitytransmission. This mode of operation isextremely attractive for interconnectingsmall stations situated in remote locations.For instance, Alaskan villages can beconnected to a central communicationnetwork through inexpensive low -capacityground stations.

The key element in this system is the poweramplifier at the output stage of thetransmitter in the satellite transponder.Until now, travelling wave tubes (TWTs)have been used for this application.However, to obtain a sufficiently lowintermodulation distortion, powerfulTWTs have been operated at an outputpower 10 to 15 dB below their maximumcapabilities. As a result, their efficienciesare low (about 4%), which is detrimental insatellite systems. Thus, an amplifier featur-ing a high linearity together with a highefficiency is clearly needed. This papershows that amplifiers using GaAs metalSchottky -barrier field-effect transistors(MESFETs) can meet this need.

A MESFET for replacingTWTsAlthough our goal is to develop a 20 -dBmultistage amplifier, presently one of thepower amplifiers has been developed andwill be described here. It provides more

52

These amplifiers will probably replace TWTs in satellitecommunications.

than 300 mW of output power at 40 dBintermodulation distortion, with 13%

efficiency and 12.5 -dB gain from 3.7 to 4.2GHz. This performance shows that we areone step closer to replacing TWTamplifiers in satellite transponders requir-ing linear power amplification.

The power MESFET we used has its GaAspellet flip -chip mounted on a copperpedestal. This ensures both a lowparasitic source connection to ground anda good heatsink for the pellet. Gold ribbonsconnect gate and drain to the carrier, andtabs connect the 0.070 -in. -long carrier tothe circuit.

Ho -Chung Huang joined RCA in 1969 andhas been heavily engaged in microwavefabrication technology, device physics, andcircuit interaction since 1970. He initiatedthe GaAs Impatt program at RCA andproposed a high -low junction Impatt struc-ture, now widely adopted, for the improve-ment of dc-to-rf conversion efficiency. Healso directs the fabrication of GaAsMESFETs for high -power applications.

Contact him at:Microwave Technology CenterRCA LaboratoriesPrinceton, N.J.Ext. 3349

Authors Huang (left) and Sechl.

This type of MESFET features a gatelength of approximately 1 Am with a totalgate width of 3000 µm obtained by con-necting 20 gates in parallel. When tested atsaturation, these devices can deliver morethan 1 W of output power at 4.2 GHz with apower -added efficiency of 37% and a small -signal gain of 13 dB.

Optimizing performanceFor our application, the FETs had to beevaluated for intermodulation perfor-mance. While carrying out this evaluation,with the device mounted in a test fixture, itbecame clear that the rf output tuning for

Franco Sechl designed solid-statemicrowave radio link equipment for ITT inMilan, Italy, before joining RCA ElectronicComponents as a design engineer in 1968.In this position he designed various types oftransferred electron oscillators anddeveloped a technique for measuring theimpedance of transferred electron diodesunder large -signal conditions. In 1973 hetransferred to the Microwave TechnologyCenter at RCA Laboratories, where he ispresently developing high -powermicrowave transistor amplifiers.Contact him at:Microwave Technology CenterRCA LaboratoriesPrinceton, N.J.Ext. 2529

lowest intermodulation differed fromeither the tuning for maximum saturatedoutput power or the tuning for maximumgain; a systematic characterization of theactive device was needed.

Device characterization was obtained withthe aid of a computer -controlled tuner and aspectrum analyzer, both connected at theoutput of the device under test.

Fig. 1 is a simplified block diagram of themeasurement set-up. The signals from twogenerators are amplified by power TWTs,combined, and fed to the input of the deviceunder test through an input tuning circuit.The output of the device is connected to aload through the computer -controlledtuner, which consists of a coaxial slottedline with slugs riding on the centerconductor.' These slugs, driven by step-ping motors, can be positioned very ac-curately. The load impedance, ZL, is thencomputed from the position of the slugsand is plotted directly on a Smith chart.The output power can also be read by thecomputer.

For the intermodulation measurement,two equal -amplitude carriers, separated bya few MHz, are fed at the input of thedevice. The output signal contains the twoamplified carriers plus the unwanted inter -modulation products. A spectrum analyzermeasured the carrier-to-intermodulationratio, or C// ratio, in dB, between theamplitudes of the carrier and the highestintermodulation product.

The instrument was programmed to varyload impedance and search for either max-imum output power or contours of constantoutput power.

Fig. 2 is an example of the results with the rfinput power kept constant at 46 mW. Theload impedance at the center of the circle -like contours provides the maximum out-put power, and each contour is the locus ofthe load impedances producing a constantoutput power. The contours are plotted atpower steps of 0.3 dB. While the instrumentwas plotting each power contour, the C/ /was measured on the spectrum analyzerand marked on the contour. Many con-tours, corresponding to different values ofpower, were traced, and a second set ofcontours, constant C// lines, were derivedby connecting points of equal intermodula-tion. This dependence of the intermodula-tion on load impedance derives from non-linear phenomena in the active device. To agreat extent, these phenomena, such ascurrent saturation, voltage clipping, and

POWER

METER

TUNING

CIRCUIT

F2= 3.7 TO 4.2 GHz

F2 -F1 = 3 TO 6 GHz

DEVICEUNDERTEST

212'4'

SPECTRUM

ANALYZER

COMPUTERCONTROLLED

TUNER

OUT

COMPUTER

SYSTEM

PLOTTER

POWER

METER

Fig. 1Device characterization and optimization were done using this measurement set-up. Twosignals are fed to the device under test through an input tuning circuit, and the device outputis connected to a load through a computer -controlled tuner that searches for maximum orconstant output power.

Po

319mW

297mW

278 mW

259 mW

241 mW

225 mW

C/1

Fig. 2Smith -chart output produces two sets of curves. The circle -like contours give the loadimpedances producing a constant output power, with the center point giving the maximumoutput power. The other set of contours gives load impedances having the sameintermodulation. Optimum load impedance falls on a line orthogonal to both contours; thethree Z values shown are on that line.

modulation of the average carrier velocity,are controlled by the output loading.

Although more than one value of loadimpedance can provide the same outputpower, i.e., 0.3 dB below the maximumvalue, the corresponding C/1 values candiffer by more than 12 dB. Note that theseimpedance contours are plotted with areference impedance of 10 ohms. (In otherwords, the center of the chart is 10 fl.)When referenced to 50 ohms, the true

impedance of the test system, these datashow, for instance, that the 12 -dB variationin C/ / can be caused by reflection -coefficient variation of only 15%. In otherwords, the intermodulation is very sensitiveto the device's rf tuning.

This question then arose: how can oneselect the optimum load impedance fromthese data?

Certainly such impedance lies in the lowersemi -plane, as load impedances falling in

53

E

this region result in higher C/ / ratios forthe same output power. Also, for a cons-tant C//, the best load impedance is the oneclosest to the center of the power contours.Thus the optimum load impedance will fallon a line orthogonal to both the C// andpower contours. Since the rf input power isalso a variable, similar measurements wereperformed at different values of inputpower to define the relationships betweeninput power, output power, and inter -modulation at fixed values of load im-pedance, for instance, Z1, Z2, and Z3.

Fig. 3 plots output power vs C// for thethree different load impedances Z1, Z2, andZ3, chosen in the optimal area for inter -modulation performance. At a constantvalue of C/ /, 40 dB for instance, Zi givesthe highest output power, but the gain islowest, while Z3 gives lowest power buthighest gain: the marked output powerswere measured at constant input power.These are the data that a designer needs inorder to choose the load impedance for thebest compromise between output power,intermodulation, and gain. Moreover, onecan predict the variation of the C// for avariation of the input and output powers.These measurements, repeated at differentfrequencies, defined the optimum loadingover the full operating bandwidth.

Amplifier design

The circuit design of the amplifier can beoutlined as follows: the output circuit iscomputer -optimized first to present theFET with an impedance that closelyfollows the optimum load impedance forbest output power and low intermodula-tion distortion over the operating

20 25 30 35

C/I (dB)40 45

bandwidth. Then the active device,characterized by its S parameters, is loadedby the optimized output circuit. Finally,the input circuit is computer -optimized forhigh and constant gain over the operatingbandwidth. This procedure results in anamplifier having nearly optimum powerand intermodulation distortion over theoperating bandwidth while still main-taining, over the same bandwidth, high andconstant gain.

The optimum load impedance for thedevice described varied from 10 + j 0 SI at3.7 GHz to 10 + j2.5 CI at 4.2 GHz. Thissmall variation of reactance over frequencyis attributed to the low -parasitic package.

The output circuit, a double X/4transformer, also was designed to followthe optimum load impedance closely overthe operating bandwidth. The impedanceplots show the excellent tracking betweenthe two curves. The input impedance of thispower FET is approximately 3 II Theinput tuning circuit was designed as adouble X / 4 impedance transformerpreceded by a X/ 2 resonator, which broad -bands the tuning circuit so that a relativelygood match can be achieved over the fullbandwidth. Fig. 4 is a photograph of theamplifier.

Amplifier performance

The frequency response of the amplifier isdescribed in Fig. 5. At 25 mW of inputpower, the output power is 410 to 490 mWover the operating bandwidth, with anassociated gain of 12.1 to 12.9 dB. At 100mW input power, the amplifier deliversmore than 1 W with a power -added

efficiency of 36 to 39%. Although the gainfor this single -stage amplifier is high, thereare no gain peaks at low drive that couldlead to potential instability.

Fig. 6 and Table I give the intermodulationperformance measured at the high side ofthe bandwidth with two equal -amplitudecarriers 6 MHz apart. The output power,power -added efficiency, and input powerare shown as functions of CI L For in-stance, at an input power of 17 mW, C// is40 dB, with an output power of 300 mWand a power -added efficiency of 13.3%.

The output power and efficiency remainremarkably constant.

Over the operating bandwidth at an inter -modulation of 40 dB, the power remainsbetween 300 and 319 mW and the efficiencybetween 13.3 and 14%. Also, the gain of12.2 to 12.9 dB is considered high for asingle -stage broadband amplifier.

Efficiency is better than for TWTAs.

But perhaps the most important feature inthis amplifier is the high efficiency at lowintermodulation distortion. Although theefficiency of 13-14% at a C// of 40 dBwould drop to 9-10% for a multistage 60 -dB -gain amplifier, that value is still farbetter than what is presently achievablewith other amplifiers-a typical high -gainlow -power FET amplifier, operating in thesame frequency range, has an efficiency of1.5% at a C/ / of 40 dB. Bipolar amplifiersare slightly worse, and a double -collectorTWTA has an efficiency of about 4%.

Fig. 7 shows the gain and the phasebetween the amplifier's input and output rf

Fig. 3 (left)Output power plotted against intermodulation for the three load impedances chosen fromFig. 2. Designer must use these curves to make the best compromise among output power,intermodulation, and gain.Fig. 4 (above)Linear amplifier has FET at center. Quarter -wave input transformer is built on 5 -milsubstrate; rest of circuit is built on 25 -mil substrates. Output circuit, composed of two morequarter -wave transformers, is followed by 50 -ohm line.

54

signal as functions of the input power andgate voltage. (These are single -carriermeasurements.) Gain variations and phasedistortions produce intermodulation dis-tortion. For a peak envelope input powerof 34 mW and a gate voltage of -2.34 V,there is a slight gain compression and aphase distortion of 2.5%. Under theseconditions, the measured C// was 40 dB.At a gate voltage of either 2 or 2.5 V, theintermodulation performance degraded by5 dB. Since in this range of gate voltages theamplitude characteristic maintains thesame shape and changes monotonicallywith the gate voltage, but the phasecharacteristic undergoes a significantchange in shape, we can conclude that achange in phase distortion is responsiblefor the variation in intermodulation.

ConclusionThe power amplifier described here is

highly linear, highly efficient, and operatesover a wide frequency band. Specifically, itprovides more than 300 mW of outputpower over the 3.7-4.2 GHz range with acarrier-to-intermodulation ratio of 40 dB,an efficiency of 13-14%, and a gain of 12-13dB. These values of efficiency are far above 300

what is presently available either withsolid-state or TWT amplifiers. The keyfactors in achieving this performance werethe development of high -efficiency high -linearity MESFETs and the developmentof an amplifier design technique that isbased on a device characterization forintermodulation performance. Theresulting amplifier has nearly optimumpower, intermodulation distortion, andgain over a broad bandwidth.

Acknowledgments

We thank L. Carr, W. Sked, and F.Wozniak for fabricating the MIC com-ponents, and E. Mykietyn, J. Brown, andA. San Paolo for assembling theMESFETs and circuits.

References

I. Huang, H.; Drukier, I.; Camisa, R.; Narayan, Y.; and Jolly, S.;"High efficiency GaAs MESFET amplifiers," Electronics

Lett. Vol. II, No. 21 (Oct 16, 1975).2. Huang, H.; Drukier, I.; Camisa. R.; Jolly, S.; God, J.; and

Narayan, Y.; "GaAs MESFET performance," Digest ofInternational Electron Devices Meeting, Washington, D.C.(1975).

3. Perlman, B.; Sechi, F.; Paglione, R.; and Schroeder, W.; "Anautomated load -pull test system," private communication.

Reprint RE -23-3-7A similar version of this paper was presented at theInternational Solid State Circuits Conf., Phila., Pa., inFebruary 1977.

10 0 mW

1000900 - Pu, o 50mW800 - Of-

700 -

W6006- P = 25 mW

0= 500-

cr 400-w

0- 300-

200-

1003.6

-Operating Bandwidth

V0" 7.0V

Ve -2.24 VI0m 300rne,

3.7 3.8 3.9 4.0

Frequency (GHz)

4.1 4.2 43

Fig. 5Frequency response of amplifier shows no potential instability despite high gain.

600

500

400

200

1009080TO

so

40

30

20

25 30

13

35 40C/Ile18/

50

0

Table IOutput parameters remain constantover the entire 4-GHz band.

Frequency (GHz)3.7 3.95 4.2

Purr (mW) 304 319 300

n (%) 13.3 14.0 13.3

Gain (dB) 12.2 12.9 12.3

Fig. 6 (left)I ntermodulation performancemeasured at the high end of thebandwidth shows good efficiencyand gain at 40 -dB operating point.

Fig. 7 (below)intermodulation distortion iscaused by change in phase distor-tion, as curves of gain and phase vs.input power and gate voltage show.Phase characteristics have 2.5 -degree phase dip that produce 5 -dBperformance degradation; gaincharacteristics show no significantchange in shape.

12 -

4.2 GHzVe=-2.00V

- 2.24V-2.50V

303 10PIN (mW)

2.fD° - 0

-2,52i"/- -4 ta--6

0.

100

55

Receiver voting extends two-way -radio range

D.D. Harbert) R.G. Ferrie

Low -power personal, portable, and mobileradios generally have talk -back rangesmuch shorter than the talk -out range oftheir higher -powered base stations.Receiver voting is one method of remedy-ing this situation-it electronically selectsthe best audio signal from two or moreremotely located receivers that are receiv-ing the same message. Land lines ormicrowave links connect the remotelylocated receivers to a central location,where the selection takes place.

RCA Mobile Communications Systems, inMeadow Lands, Pa., has developed such avoting system; in it, a signal -qualityevaluator circuit for each receivergenerates an output voltage indicative ofthe signal-to-noise ratio at its input. Thesignal -quality voltage of all the receivers issampled periodically, and the best audio is"voted" and switched to the dispatcher.The selection is held until a SI N improve-ment of at least 2 dB in another receiverchanges the vote.

The voting system is designed to operatewith narrowband vhf and uhf fm radios.They operate on the land -mobile fre-quencies assigned to government agencies,such as police and fire departments, andindustrial and public users, such as truck-ing and taxicab fleets.

Receiver voting applicationsMobile and portable transmitters need theextended range possible with the votingsystem because their output powers areintentionally held to low values to conservespace and power. Voting systems are alsogenerally operated in areas where reception"shadows" exist because of hills, buildings,and bridges.

Fig. 1 shows a typical example of a receivervoting application. In this example, thebase -station location and effective outputpower are selected to provide an adequatesignal strength over the desired coverageareas, as shown by the talk -out contour.

PORTABLETALK BACKCONTOUR

Adding power increases the range of a portable radio, but italso increases weight and cost. Voting receivers extendrange without these disadvantages.

Voting comparator equipment panel contains the modules necessary for a two -channel,four -receiver -per -channel voting system comparator station. Each channel requires apower supply, a control module, and a comparator module for each receiver.

DESIREDCOVERAGEAREA

1. BASE STATION WITH VOTING RECEIVER

X SATELLITE STATION WITH VOTING RECEIVER

DISPATCH CENTER

BASE STATIONTALK OUTCONTOUR

Fig. 1

Strategically located satellite receivers increase the talk -back range of low -power portableand mobile radios.

Remote "satellite" receiver stations arestrategically located to insure that at leastone receiver will be within the talk -backrange of any portable transmitter withinthe desired coverage area. The audio out-put of each satellite receiver is connected byphone line or microwave link to a commonpoint called the comparator station, wherethe best -quality audio signal is selected.Thus, the talk -back range of portable ormobile transmitters is extended by usingphone lines to complete the communica-

tion path to the dispatcher. The com-parator station is generally located at eitherthe base station or the dispatch center, butcan be at any convenient location.

Types of voting systemsReceiver voting systems began to appear inmobile -radio networks in the mid -fifties.Their growth has been steady, with a recentimpetus provided by increased use of port-able transceivers. Today all major

56

manufacturers of mobile radios offer theirown proprietary voting -receiver equip-ment. The means of selecting the "best"signal for the dispatcher have been refinedover the years.

The early receiver voting systems simplyselected the first receiver with an inputsignal above the squelch operatingthreshold and maintained the initial selec-tion for the duration of the message.

In these systems a new vote occurred witheach new message. Known as "race voting,"this is unsatisfactory in many situationsbecause in practice the best signal will shiftfrom one receiver to another during atypical message. The recognition of thislimitation led to an improved systemknown as "tone -quantizing."

The tone -quantizing system uses voice -band tones generated at the receiver torepresent the quality of the receiver signal,as indicated by the noise quieting.

In this system, the receiver sending thecombination of tones representing the"best" signal to the comparator station isselected. Tone -quantizing permits con-tinuous voting in the middle of a message;but in order to conserve tones, the receiversignal is divided into rather large segments,typically 10 dB, which are somewhatcoarse. Additionally, the performance suf-fers because the in -band signaling tonesmust be filtered from the speech audio.

Tone -quantized voting, through, does notaccount for noise introduced by the phoneline.

Because of this noise, it is possible that thedispatcher could be listening to a signalthat is not the best available. The

RECEIVER STATIONS

SITE A

RECEIVERVOTING

TONEENCODER

SITE B

RECEIVER

SITE C

COMPARATOR STATION

Why use voting receivers?

Because of size and weight limitations, personal two-way radios are low -powered (1 to 6 W compared with 10 to 100 W for vehicle radios). The votingreceiver system allows users to increase the range of their lightweight low -power radios by providing a network of intermediate receivers. The signalsfrom these receivers all go to a control point and are "voted" on; the best -quality signal is the "winner" and is selected for listening.

Besides the advantages of keeping personal radios portable, the votingsystem has another advantage-cost, especially in newly installed systems.Better communication systems can often result from investing in votingequipment, rather than a large number of more expensive radios.

limitations of tone -quantized voting led tothe development of a technique in whichthe evaluation circuits operate at the listen-ing or "dispatch" point, thus includingtelephone -line noise. This eliminated theobjections to the previously discussedsystems and is now the method of choice onmost new designs.

Signal quality is determined differently bydifferent manufacturers.

The most common method of choosing thesignal is to simply measure the system noiseduring speech pauses and select the channelwith the least noise as "best." This issatisfactory providing the telephone linesare adjusted and maintained to have thesame frequency response and attenuation.RCA uses the ratio of speech peaks to noisequieting during speech pauses as the figureof merit for evaluating signal quality. Theadvantages of this technique are pointedout in the circuit description.

VOTED AUDIO OUTPUTif (TO DISPATCHER OR

BASE STATION)

V V V VPOWER

C R R RSUPPLY MCC C

VOTING I

TONEENCODER

RECEIVERVOTING

TONEENCODER

/ RECEIVER AUDIO SIGNALSOR SQUELCH TONE

(VIA PHONE LINES OR RADIO LINK)

VCM = VOTING CONTROL MODULE

VRC = VOTING RCVR. COMPARATOR MODULE

Fig. 2Each receiver station is connected to a comparator station,where the best audio signal is selected and sent to thedispatcher.

FFECEIVERT

AU ,OUT

I

SQUELCHI,

SWITCH

I I

RCA's receivervoting systemFig. 2 is a block diagram of a typical votingsystem. At each of the remote "satellite"stations, a voting -tone encoder (VTE)module encodes a squelch -status tone ontothe phone line to the voting comparatorequipment panel. This panel has a votingreceiver comparator (VRC) module foreach satellite receiver and a voting controlmodule (VCM) for each group of receiversoperating on the same frequency. When asignal is being received, the audio quality ateach VRC is continuously monitored, andthe best audio is automatically selected foruse by the dispatcher.

Fig. 3 is a block diagram of a single -channelvoting receiver satellite station. The voting -tone encoder switches the squelch -statustone onto the phone lines when the receiveris squelched and receiver audio when thereceiver is unsquelched. The squelch -status

AUDIOLEVELADJUST

SQUELCHSTATUS

TONEOSCILLATOR

L_

VOTING TONEENCODER MODULE

LINETONE/AUDIO I LEVELSWITCH ADJ.

TONE LEVEL7." ADJUST

A+

POWERALERT

OSCILLATOR(OPTIONAL)

POWERSENSE

LINEDRIVER

7-0 TO

LINESTEL.

GNI)-T -Fig. 3At the receiver station, a squelch switch is used to switch eitherreceiver audio or the squelch status tone onto the phone line to thecomparator station.

57

tone is used at the comparator station toensure that an open or shorted line is notvoted. The squelch switch in the receivercontrols the tone/ audio switch. Theoptional power -alert oscillator warns thedispatcher when the satellite station is

being powered by the emergency batterypack.

At the comparator station (Fig. 4), the SI Nevaluator circuitry provides an outputvoltage representing the signal-to-noiseratio of the input signal from each receiver.This signal -quality voltage is then com-pared to ones from all other comparatormodules. The module with the "best" signalis then voted by the selection -and -prioritycircuit and its audio applied to the controlmodule by way of the voted audio switchand the voted audio bus. To ensure that asignificant improvement has occurredbefore the vote changes, the signal -qualityvoltage of the voted module is artificiallyenhanced. The selection circuitry of eachmodule works in conjunction with thevoting rate timer and ramp generator onthe control module, and a priority circuitprevents voting more than one module at atime. The fault -detection circuitry applies adisable input to the voted audio switchcontrol to prevent the closing of the votedaudio switch if neither tone nor modulationhas been present for a period of fiveseconds; reception of a squelch tone ormodulation enables the voted audio switchcontrol circuitry.

Audio quality considerationsThe sole purpose of a mobile com-munications system is to convey informa-tion to and from the dispatcher. To ac-complish this task efficiently, an intelligiblehigh -quality audio signal must be main-tained. A discussion of speech quality andintelligibility is beyond the scope of thispaper, but the interested reader is referredto Ch. 3 of Ref. 1 for an excellent summaryof the factors affecting audio quality andthe means of relating intelligibility tomeasurable system parameters by use ofthe "articulation index."

The voting system was designed to inter-face with existing equipment that has asignal with more -than -adequate qualityand intelligibility for the intended use.Therefore, the design goals were to ensurethat the voting system did not cause anyappreciable degradation of the audio quali-ty and intelligibility.

To maintain a high -quality voted audiosignal, special care was taken to keep the

O0-

C VOTEDAUDIO

SWITCH

INPUTa

ALC

S/Na

N./

EVALUATORENHANCEMENT SELECTION

ST'TUINDICATOR

aPRIORITY

SO TONE VOTED AUDIOFAULT a SWITCH

DETECTION CONTROLMANUAL CONTROLS

IVCM

oCONTROL OUT

I VOTED AUDIO OUT

+V

TG

TO ADDITIONALCOMPARATOR

MODULES

nnnnn

F) GENERATORRAMP 4,

))VOTINGRATE < 4. >>-TIMER

i >>

1

MUTE IN0

AUDIOPROCESSING

SO. TONENOTCHFILTER

0

0

>

>>

CC

U 0J

LAI Cr

IFig. 4At the comparator station, a voting control module (VCM) works in conjunction with a votingreceiver comparator (VRC) module for each receiver station to select the best -quality audio.

Ron Ferrie joined RCA in 1972 as a memberof the engineering staff, working with theMobile Data Products group. In 1974,became a Leader and was assigned toPortable Products, where he became in-volved in the VOTEC receiver voting system.Contact him at:Portable ProductsMobile Communications SystemsMeadow Lands, Pa.Ext. 6410

Don Harbert was responsible for the designof the receiver voting system describedhere. Since writing this article, he hasreturned to Broadcast Systems at MeadowLands, where his previous major assign-ment was project engineer on the TF-25FLtransmitter program.Contact him at:Broadcast SystemsMeadow Lands, Pa.Ext. 6354

Authors Don Harbert (center) and Ron Ferrie (right) with technician Vince Battaglia, whoalso worked on the voting receiver project. Equipment shown is the voting comparatorequipment panel, set up for one -channel, two -site operation.

58

PEAKDETECTOR

K log Ep SIGNAL0 QUALITY

PRECISION OUTPUTAUDIOF.W. RECTIFIERAND FILTERINPUT

)1 LOG - SUBTRACTORor -K log

Ep)EvVALLEY T+

DETECTOR K log EvFig. 5Signal-to-noise quality evaluation output is a logarithmic function of the ratio of the audiosignal during speech to the noise quieting during speech pauses (or signal valleys).

10-DB QUIETING

INPUT 0

PEAKDETECTOR 0

LOGGED, 0RECT., &

FLTR. INPUT

VALLEY 0DETECTOR

30-DB QUIETING

ciaill'404110111111111111111

I.

Fig. 6Signal-to-noise evaluator waveforms here correspond to locations A through Don Fig. 5 for10 -dB and 30 -dB quieted signals.

audible switching disturbances whenchanging votes as low as practical. This wasdone by using CMOS transmission gatesfor the voted audio switches and con-necting them in such a manner that no dctransients are generated when the switch isopened and closed. In addition, the signalsbeing switched are almost identical, sincethe ALC circuit at each comparator inputsets the audio levels within 2 dB of eachother. Changing votes from one module toanother occurs in less than one millisecond.Laboratory tests have indicated thatabrupt 2 -dB changes in the speech signallevel cannot be heard with the rate ofchange normally encountered in a votingsystem.

The audio distortion was kept below ameasured 0.35% for all voting -systemmodules by properly biasing the CMOStransmission gates used for the audioswitches and by using an IC audio poweramplifier for the line -driver amplifiers.

The frequency response of the votingsystem is within 1 dB of the input from 300Hz to 3 kHz. The system here includes thevoting -tone encoder input to the voting -comparator phone -line output with theexception of the notch filter and thetelephone -line response. The notch filterhas a 30 -dB bandwidth of 5 Hz.

From Ref. 2, a 300 -Hz to 3 -kHz bandwidthprovides a maximum articulation index of0.7, with a corresponding word articula-tion of 85 of 90%. The voting system

reduces this by 3%, for a word articulationof 82.5 to 87.3%. From Ref. 3, the sentencearticulation for this word articulationwould still be in the 95-100% range,depending on the training of the speakersand listeners.

For low S/ N signals, the noise level can bebetween the threshold of audibility and theminimum speech levels, and so will reducethe articulation index and the intelligibilityaccordingly. Thus, to provide the dis-patcher with the most intelligible signalavailable, the receiver with the highestspeech -signal to noise -floor ratio must beselected.

Signal -quality evaluator

RCA's method of measuring signal qualitycan be understood by referring to Fig. 5.The log amplifier and precision rectifierand filter generate a signal that is theenvelope of the logarithm of the inputsignal. The envelope signal is thenamplified and applied simultaneously to apeak detector and a valley (or noise -quieting) detector. The outputs from bothdetectors are applied to a subtractor, whichis arranged so that its output voltage is E.=-K (log 4 - log Ev) = -K log (El Ev),where 4 is the output from the peakdetector and Ev is the output from thevalley detector. Thus, an increasing signal-to-noise ratio will send the output towardsground; a decreasing signal-to-noise ratiowill cause the output to go positive. Fig. 6demonstrates this action by showing

typical waveforms at various points in thecircuit. C and D are the respective outputsof the peak and valley detectors.

The major advantages of using the speech-peak/noise-quieting ratio for determiningsignal-to-noise ratio are:

1) The output of the signal -qualityevaluator is independent of the inputsignal level.

2) The output is a logarithmic function ofthe input -signal/ noise -quieting ratio.3) The true signal-to-noise ratio is

measured, which automatically takesinto account the transmitter deviation,the noise -quieting at the receiver, andnoise introduced by the phone line.

Using the above technique, the evaluatorcan indicate the input -signal/ noise -quieting ratio with an accuracy of 0.6 dB,

Selection circuitryThe method for selecting the comparatorwith the best -quality audio is analogous to asample -and -hold technique.

The signal -quality voltage from each com-parator module is evaluated periodically,the module with the best audio is "voted,"and its audio is switched to the voted audiobus. At the end of the "hold" period, thesignal quality of each comparator moduleis again evaluated. If a module other thanthe one initially "voted" has a better -quality audio than the original, the votewill change to the module with the bestsignal. An enchancement circuit does notchange the audio quality, only the signalthat represents the audio quality. Note thatthe voted audio switch of the voted moduledoes not open during the evaluation periodand will open only if the vote changes.Switching the audio from one module toanother occurs in less than one millisecond.

The voting rate, or more precisely the timebetween evaluations, is adjustable by vary-ing the period of the multivibrator on thecontrol module. The voting rate is set at 50milliseconds during factory tests, but isadjustable over a wide range. This sampleperiod provides an average of 4 evaluationsper syllable.

To select the comparator module with thebest -quality audio, a ramp signal isgenerated in the control module and appliedto the inverting input of a threshold detectoron each comparator module.

The output voltage from the signal-to-noise evaluator and enhancement circuit is

59

applied to the noninverting input. As thesignal quality improves, the signal -qualityvoltage goes towards ground. When theramp goes from ground to + V, the firstthreshold detector that detects an equal -magnitude ramp signal and signal -qualityvoltage will be the module with the best -quality audio.

Fig. 7 gives a description of the evaluatorcycle. In the rest state (all receiverssquelched), all signal -quality voltages arehigher than the ramp threshold, thethreshold detector output is high, and themultivibrator is turned offf.

When a receiver in unsquelched, theevaluator voltage goes below VTH and: The threshold detector output goes low, The S/ R flip-flop is set, The voting rate timer (M.V.) is started,forcing the ramp voltage to ground, and The threhsold-detector output goes high.

At the end of the 50 -ms voting -rate timerperiod, the negative -going edge of themultivibrator output resets the flip-flop,and the ramp voltage starts towards + VTy.

When the ramp voltage equals the signal -quality voltage on any of the comparatormodules, the above sequence repeats.When all receivers are squelched, the rampvoltage goes to + V threshold and remainsthere awaiting another receiver to un-squelch. Other circuits (not shown) controlthe voted audio switch and ensure that onlyone module at a time is voted. The os-cilloscope waveforms of Fig. 8 show thesignal -quality voltage and the ramp signalat the threshold detector inputs.

Field testsRCA Mobile Communications Systemsinstalled a three -site voting system to maketests under actual field conditions as acheck on earlier controlled laboratorytests. The voting comparator, one of thesatellite receiver stations, and the basestation were located at the RCA plant inMeadow Lands, Pa. One of the satellitereceivers was located on a hilltop ap-proximately 4.5 air miles northeast of theplant and the remaining site was located atradio station WARO, approximately 7 airmiles northeast of the base station. Theterrain was hilly, with peaks between 1200and 1400 feet above sea level and valleys aslow as 950 feet above sea level. The basestation was at approximately 1000 feetabove sea level. The sites and frequencychosen (450 -MHz band) produced a testsystem simulating worst -case field con-

FRC- - -COMPARATOR MODULE

THRESHOLDDETECTOR

SIGNALQUALITYVOLTAGE

TO OTHERCOMPARATOR

MODULES

C M- 1CONTROL MODULE

RAMPGENERATOR

L__

S/N QUALITYVOLTAGE 0

THRESHOLDDETECTOROUT

SR LATCHOUTPUT

MULTIVIBRATOROUTPUT

,

Fig. 7In the selection circuitry, the ramp generator output is applied to the input of the thresholddetector on all comparator modules. The first module with signal -quality voltage equal tothe ramp signal will be the one with the best signal quality and hence will be voted. At start ofa message (A), signal -quality voltage is lowered to produce an artificial improvement inquality. At end of message (B) signal -quality voltage returns above ramp threshold.Enhancement prevents vote -changing without a significant signal -quality improvement.

SIGNAL -QUALITYVOLTAGE

RAMP GEN. OUT

MIMEWM= IIIrA1111111111111111

Fig. 8Selection -circuitry waveforms show interaction between ramp signal and signal -qualityevaluator. When the ramp signal and the signal -quality evaluator output (point E of Fig. 5)are equal, the ramp signal is forced low until the next evaluation occurs.

ditions with numerous shadows and blindspots.

During the field tests, both mobile andpersonal radios were used for talking backto the base. The listening tests were con-ducted at various vehicle speeds and with apersonal radio with the operator standingstill and walking.

The field tests verified the laboratory testsby showing that: 1) the talk -back range ofthe mobile and portable radios wassignificantly increased by the remotereceiver sites; and 2) the best availableaudio quality was maintained by con-tinuously voting the receiver with the best

quality audio. The tests also showed thatthe voting -rate timer period, the 2 -dBenhancement, and the evaluator -circuittime constants established during designand laboratory testing were correct foractual field conditions.

References

I. Hamsher, Donald H. (ed.); Communications SystemEngineering Handbook, McGraw Hill, New York, 1967. SeeChaptcr 3, by Willard F. Meeker.

2. Op. cit. pp. 3-15.

3. Op. cit., pp. 3-9, Fig. II.

4. Meeker, Willard F.; Private communication concerningsyllabic rate and duration of speech pauses for average speech.

Reprint RE -23-3-5Final manuscript received September 21, 1977.

60

Managing RCA Globcom's communication networkthrough automation

With the worldwide communication industry growing rapidlyand demanding more sophisticated services, RCA Globcom'smanagement faced future costs of operation risingmore rapidly than revenues. Globcom's engineers faced achallenge to reverse the trend; thus, Automated CircuitManagement (ACM) was born.

RCA Globcom is a partner in a worldwide network of copperwire, terrestrial microwave links, submarine cables, andcommunications satellites.' The other partners are privatecorporations, government -owned or -controlled cor-porations, and governments themselves.2.

Operating this international network and resolving itsday-to-day problems have been done on a technician -to -technician, office -to -office basis for over a century, buttoday's network is too large and too fast, and the volume oftraffic is too great, for old technology. The network itself hasbeen highly automated to handle the traffic load with lineswitches and store -and -forward message switches. Thispaper describes the parameters and rationale forautomating the management of the network.

Automation of network managementFor automation to be effective, the circuit management schememust be oriented to automation.

Automation in the communications environment meansshifting the circuit control emphasis from continuousmanual observation or monitoring to a system of thresholdalarms on technical parameters, automatically monitored,with failures only reported. In the plant record area, it meansa change from circuit cards and diagrams to route lists andequipment lists, appropriately formatted for fast retrieval ona video terminal. These are substantive changes in

operating philosophy that must be accomplished gradually.As each system function is automated, the new proceduremust function alongside the old as equipment is changedand personnel are retrained.

Globcom's Automated Circuit Management (ACM) is three-fold. First, the operating philosophy must be converted andthe threshold alarm system established. Second, anautomated data network must be implemented to tie allparts of the system together. And, third, a data base file andmanagement system must be installed. When completed,the system will provide:

A central service coordination center to receive troublereports and information from sources outside thenetwork. A systemwide data communications network that willautomatically deliver operating information entered byany of the alarms or stations on the network to every otherstation that needs to know, based on a header formatcontaining circuit and service identifiers.

A. Acampora

A data storage and retrieval procedure to collectoperating data from the communication network andproduce exception reports periodically, and on com-mand.

An on-line plant record system that will provide,through remote terminals, circuit and operating recordsto engineering and operations management on com-mand.

Retrieval programs that will provide service quality andoperating statistics from the data base.

If we define a circuit in the communication service as thecarrier of information between the terminals of a bearerfacility (such as a cable or radio system), we can consider

Photo credit: Al Garratt

Author is shown at diagnostic console, which is used to accept thetouch-tone channel selectors and specialized signal simulators. Atthis console, one skilled technician can completely analyze achannel.

Allonse Acampora has worked in advanced communications forRCA since 1959. His current responsibilities as Staff Engineerinclude systems planning and wideband transmission disciplines.Contact him at:OperationsRCA Global Communications, Inc.New York, N.Y.Ext. 2262

61

the network as a series -parallel combination of circuits,each circuit carrying a share of the telex, telegram, and datacommunication to all parts of the world. These circuitsconnect the 15 operating offices of RCA Globcom with eachother and with foreign correspondents' offices throughoutthe world. The offices are equipped with multiplex equip-ment to derive teletype channels from voice -grade circuits,computer switches to switch telex circuits and to store andforward telegrams, as well as sophisticated storage andswitching equipment serving the private networks of anumber of large subscribers. This equipment and thetransmission networks connecting it are all subject tovarious faults, which in the classic manual mode ofoperation are brought to the attention of the operatingpersonnel via the complaint telephone. Each problem ischecked and passed from one office to the next until thetrouble is located. The record or trouble ticket, kept bypencil, is as cumbersome as it is costly.

Automated Circuit Management is a family of compatibleprocedures supported and directed by hardware and software.

The procedures for Automated Circuit Management in-clude ordering, implementing, customer filing, circuitrouting, and troubleshooting. The hardware includes threecomputer technologies-intelligent alarms and terminals, adata -communication network, and a data -base storage andmanagement system. The roster of compatible hardwareincludes input/output devices for various size offices andtraffic volumes. Because the system involves automating analready large network without disturbing its day-to-dayoperation, each segment must be added incrementally andmust not adversely affect those functions alreadyautomated or those functions still in the manual mode.Continuity in the operating records must be maintained,and the network will grow substantially in size during thetwo-year period it takes to be fully automated. Where thereis any uncertainty, pilot models and pilot procedures aretested before full implementation. Personnel using thesystem will be trained, sector by sector, as each majorsegment is added.

Hardware installationThe hardware installation will be implemented in threephases. First is the design and installation of test consolesand alarm sensors. The second phase is the implementationof a data network; third is the implementation of a data -basesystem. To allow the development and testing ofprocedures and to start the operating personnel on thelearning curve concurrently with the hardware and softwareprocurement, the communication system will be im-plemented in a limited number of RCA Control Centersusing two channels in RCA Globcom's Aircon system.

Phase one is the design and installation of sensors and testconsoles.

The RCA Globcom transmission equipment consists ofvoice control amplifiers, equalizers, and multiplex equip-ment for deriving teletype channels from the voicebandwidth circuits. Several generations of equipment arerepresented, ranging from the FDM (frequency divisionmultiplex) racks first installed in the late 1950s to the most

modern TDM (time -division multiplex) racks used with theall -digital T -carrier systems. The present -generation equip-ment has self -test functions and alarm sensors built in. Theolder equipment relies on pilot lamps and operators toassure proper operation. At the outset of ACM hardwaredevelopment, sensors must be developed for application toolder equipment where none were provided. In many cases,this is a simple carrier detector that is available in themarketplace. Where voice is the communicating medium,or where there are alternate voice and data signals present,simple carrier detectors are inadequate, so we have builtenergy detectors with settable thresholds to sense thevarious states expected to be on a circuit. A microprocessoris then programmed to read states of the group of energydetectors on a particular circuit and read out a preparedmessage to a terminal should it detect a disallowedcombination.

A pilot model of a microprocessor -alarm readout has beenin operation for several months.3 This project in the ACMfamily is a stand-alone that is a fully compatible prerequisiteto the planned data communication network and data basesystem in phases 2 and 3. The second change inmethodology is the shift to single -point testing.

Troubleshooting has three separate functions-fault detec-tion, fault isolation, and restoration. Computer -basedswitches can apply logical tests to the incoming data as wellas self testing, and provide readouts which, when coupledwith intelligent alarms, detect a large share of the operatingproblems. Fault isolation requires some manual interven-tion; nevertheless the time and labor content required toisolate faults can be reduced by the concept of single -pointtesting-i.e., consoles containing modern semiautomatictransmission -measuring instruments, video terminals forcircuit monitoring, and touch-tone selectors to bring circuitends to the console. Additionally, built-in signal generatorsand simulators permit one skilled technician to observe andanalyze a channel without moving test equipment aroundthe operating center, patching lines, or performing otherperfunctory tasks.

These consoles stand alone as diagnostic tools in phase 1,ready to accept the touch-tone channel selectors andspecialized signal simulators which follow as the automa-tion program progresses. The basic consoles contain thesame instrumentation and communication package for allcontrol centers, but the size and nature of the control centerwill determine the number of consoles required and thespecial simulators needed.

Phase two-the implementation of a data communicationsnetwork-follows the establishment of intelligent alarms and testconsoles.

While the data network could stand alone, its effectivenesswould not be fully realized. It would be merely an expensivesubstitute for the telephone and telex. The communicationsnetwork is a prerequisite to the data -base system because itprovides interconnection of the intelligent alarms andconsoles beyond the capability of the telephone and telex.The network will reach its full maturity when it inter-connects the alarms, consoles, and data base.

62

SanFrancisco SFLodi LD

HonoluluHU

GuamAG

Data Bus

RCA Globcom has 15 operating centers systemwide,located in the continental United States and at various sitesin the Pacific and Caribbean areas. In addition, RCAGlobcom has representatives in Europe and Asia who needcertain information from the operating system and database. Fig. 1 shows RCA Globcom's operating network andthe off -net extensions. Data speeds range from 300 to 9600baud, depending on load. The plan is to have a pollednetwork, which is not unique in data communications. RCAGlobcom's AIRCON system provides a similar service to thepublic and will be used to train personnel in automatedsystem procedures.

The third phase of ACM, the data base system, is the keystone ofautomated operation.

Phases one and two are the prerequisites. The data file isrelatively simple. It is a collection of "one liners," eachidentified by a circuit designator, service designator, andmessage class. All video terminals, and alarm readouts, aswell as the other computers in the system will be directlyconnected to the data base system through the com-munications network. The automatic addressing features ofthe communications networks are intimately related to thestorage and processing scheme.

Network operationAll messages entered into the communications network willbe addressed and segregated by that network into:

Operational messages to be stored and available forretrieval for a specified interval.Operational data messages to be stored for qualitycontrol or other processed reports.Plant record data to be stored until withdrawn.Alarm data to be stored and reported to the operatingconsoles periodically until cleared.Implementation schedules.Emergency bulletin messages.

These messages, identified by service class, will be markedfor compilation into daily, weekly, and monthly service

MiamiMI

HaitiHI

New York NY

Rocky Point RP

Kingsbridge KCWashington WN

SantoDomingo

SD

Fig. 1Operating network and the off -net

extension. This data communicationsnetwork includes 15 Globcom operating

centers and operates at data speedsfrom 300 to 9600 baud.

San JuanSJ

reports to management for each service, at a detail levelappropriate to the management level and operating re-quirements. Access to the data base will be controlled bythe system which permits each terminal to receive only,enter new material, delete specified files, and accessspecified files, according to needs and responsibility.

Format discipline and failsafe techniques are mandatory.

The machine -generated inputs will be formatted for thedata base, and the system will reject any message whichdoes not fit one of the acceptable formats. Rejections ofmachine input will be sent to the supervisor of the offendingmachine. Those data messages formatted to require aresponse will be re -sent to the addressee until a closeoutmessage is received. Recognizing that no automatedsystem can correct its own failures, the ACM system, likethe systemwide network it controls, will be managed,around the clock, from the Service Coordination Center atRCA Globcom's Kingsbridge Communication Center inPiscataway, New Jersey.

ConclusionThe technologies involved in ACM are current state of theart. There is no part that, by itself, has not been done before.Rather, the challenge lies in the combining technologies-hardware and software-and redirecting over 1,000 peoplescattered from Guam to the Caribbean to do their jobs withnew, automated tools without adversely affecting RCAGlobcom's communications business.

References1. Hepburn, J.C.; "RCA Globcom's role as a carrier," this issue.2. Simonds, R.E.; "How the Communications Act affects you," RCA Engineer, Vol. 22, No.

4 (Dec 19761 Jan 1977) p. 94.

3. Henn, W.; "Microprocessor automated alarm system," to be published.

AcknowledgementThanks to R. Ruben, Leader, Operations Design Engineer-ing, for supplying the details of the Test Console develop-ment, as well as the photographs used.

Reprint RE -23-3-1Final manuscript received June 15. 1977.

63

Computerized inventory managementat RCA Records

D. Mishral A. Devarajan

-2 0

. SCRAP

TOTAL ON HAND INVENTORY

2 4 6 8 10 12

TIME

40

3

N

T

Y

20%

14 16

In the recorded music business, about 10% of the selectionsproduce about 90% of the sales. Should the remaininginventory be held for future sales, sold as distressedmerchandise, refurbished, or scrapped?

BACK TO INVENTORY

RETURNS

30%

RETURNS RATE

II I I I I I I. I

2 4 6 8 10 12 14 16 18 20TIME

REGULARSALE

1000/0

TOINV.

950/o

PRODUCTION RATEO

3

N

2 4TIME

TRANSFER IN

2%

TRANSFER OUT

2%

5%

CUT-OUT SALE 10%

OM%

70%

TOCUSTOMERS

6a

5

N

T

2

SCRAP

SHIPMENT RATE

I I I I I 1 I I I

0 2 4 6 8 10 12 14 16 18

TIME

Fig. 1

Recorded -music life cycle has a number of points where decisions must be made-scrap, inventory, or cut-out.Computerized analysis makes the decisions easier and helps keep the on -hand inventory curve at a cost-effective level.

64

The music business presents an environ-ment where reliable forecasting is notpossible, the customer service required isvery high, and inventory obsolescence isconsiderable. Because of this uniqueenvironment, a combination of industrialengineering techniques-aging analysis,breakeven analysis, and cost accounting-has been necessary for efficient inventorycontrol, product pruning, and inventorydisposition policies.

Unique marketing practicesproduce volatile inventories

Several industry -wide practices determinethe inventory and marketing policies to befollowed. For example, products are heavi-ly promoted at their time of introduction,and large distributor orders are bookedeven prior to publication. This makes itnecessary to produce and inventory theproduct in large quantities at that time.Also, the seller usually gives full credit forthe return of unsold merchandise. To giveadequate exposure to the product,however, returns are usually allowed onlyafter 60 or 90 days from the purchase date.Since relatively few productions are suc-cessful, the practice of giving full creditfor unsold returns creates an inventoryexplosion when the unsuccessful selectionsare returned.

The industry recently has been attemptingto recover a part of the costs sunk on theunsuccessful selections via "cut-out" ordistressed -merchandise sales, in which theinventory of unsuccessful selections is soldto specialist merchandisers at very lowprices.

Fig. I depicts the life cycle of a typicalrecorded -music product. The productionportion of the cycle starts much ahead ofsales, and returns lag shipment by a certainperiod. The nature of the demand life cycle,the extent of returns, and their timing allcritically affect the inventories carried afterthe introduction phase. They also typicallydetermine product profitability and futuredemands.

The challenges ofinventory mangementInventory management, in its pursuit ofmaximum customer service with minimuminventory investment and efficient plantoperation, basically attempts to determinehow much to order and when. Thedecision -making process becomes complex

YES

FINISHED GOODSINVENTORY

AGING ANALYSISSELECTED BASE FOR

HISTORICAL SALESRATE

YES

YES

I SALES/RETURNSCORRELATIONS

PRODUCT LIFEDISTRIBUTION

SALES/RETURNSDISTRIBUTION

SALES/RETURNSCURVES

NO

MAHUFACTURINGa INVENTORYCOST INFO

POTENTIA CUT-OUTANALYSIS

ENTER MINIMUMSALES OTY

FOR CUT-OUTELEGIBILITY

NO

FINISHED GOODSINVENTORY

AGING ANALYSISREPORT

CSTOP

C STOP )

ARTIST'SLEGALCONTRACTCONDITIONS

POTENTIALOUT -OUTS

Fig. 2Sales, aging, and cut-out analyses are the system's three major outputs. Sales analysis canbe done by artist, music type, or recording medium, or by sales/return distribution andcorrelation. Aging analysis and cut-out analysis are explained in Figs. 3 and 4.

because of the unusual characteristics ofthe recorded music industry stated above.Some of the critical inventory -management functions in this environmentare:

Measuring the accuracy of salesforecasting (subjective in the initial stageand semi -quantitative in later stages) andusing the feedback for inventory control;

Monitoring the effectiveness and successof new -product introductions bydetermining sales and returns for in-dividual selections;

Measuring the effectiveness of produc-tion and procurement ordering policies;Identifying sales characteristics andtrends of all products in the marketplace;

Tracking the returns from distributorsand retailers and establishing guidelinesfor scrapping or refurbishing returns;

Tracking inventory obsolescence for in-dividual products;Establishing reserves for future inven-tory obsolescence for proper matching ofrevenues and expenses;Measuring the effectiveness of inventorycontrol by establishing a business planfor investment in inventory;Creating economical disposition of in-active and obsolete inventories byrecommending products to be prunedfrom the catalog, scrapped from inven-tory, or sold as distressed merchandise.

The solution-computerized inventorymanagement analysisIn order to achieve effective inventorymanagement, a comprehensive com-puterized system (Fig. 2) has been

65

developed for problem analysis and deci-sion making. The major components of thesystem are statistical sales analysis,finished -goods inventory -aging analysis,and product cut-out analysis.

A three-year history of sales and returns ismaintained along with detailed productidentification.

The total information includes selectionnumber (or part number), title of theproduct, artist, product medium, type ofmusic, product release date, weekly sales,weekly returns, and inventory classifica-tion.

A standard cost file is constructed toinclude manufacturing cost and inventory -carrying cost by selection number. The"business contractual conditions file" in-dicates the legal requirements for eventualproduct disposition, telling if each selectioncan be dropped from the catalog, sold asdistressed merchandise, scrapped, etc. Thecontractual requirements for disposition ofinactive inventory vary considerably fromartist to artist.

Dave Mishra is responsible for the In-dustrial, Manufacturing, and SystemEngineering Departments at RCA Records.Besides the inventory -management pro-gram described here, he has worked onproductivity improvement in warehousingand distributing operations, indirect laborcontrol, and automated data gathering.Contact him at:Engineering ServicesRCA RecordsIndianapolis, Ind.Ext. VT -5368

The classical tools of descriptive statisticsare employed to quantify the characteristicsof product sales and returns.

Twelve months of data from the day ofproduct release is considered the absoluteminimum for statistical significance. Themajor outputs are the following:

Gross sales and returns curves, whichdisplay monthly sales and returns databy selection number and as percentagesof corresponding year-to-date figures.Artist or music type profiles, whichpresent the monthly sales and returns ofall the products released by an artist orwithin a music type.Product life distribution, whichmeasures the effective product life whenthe monthly sales value has reached anestablished minimum. A frequency dis-tribution of product life is developed,along with the arithmetic average andstandard deviation.Sales -returns correlation, computed forthe sales and returns by selectionnumber.

Dave Devarajan specializes in consultancy -type assignments of a technical/financialnature for RCA Records, using his dualbackground as an industrial engineer andcertified public accountant. He has fifteenyears of operational, teaching, and con-sulting experience in industrial engineeringin India and the United States.Contact him at:Engineering ServicesRCA RecordsIndianapolis, Ind.Ext. VT -5202

Finished goods inventory aging analysisgives information on inventory turnover byselection number.

The on -hand inventory is expressed inmonths of supply, which is calculated bytaking the average historical sales rate overa chosen period as a constant demand forthe remainder of the product life. The spanover which historical sales are averaged is acritical determinant of the computed inven-tory age; consequently, sensitivity analysescan be made for different lengths ofhistorical periods.

The aging -analysis method has evolvedover the years and proved to be quiteeffective. It categorizes the types of inven-tories as follows:

Active = 0-6 months' supplySurplus = 6-12 months' supplyObsolete = over 12 months' supply

The system ages individual items of inven-tory and presents the information by selec-tion number, artist, product medium, andtype of music. Fig. 3 shows a typicaloutput.

Product cut-out analysis identifies productsthat should be dropped from the catalog ofactive products.

The approach has been to establish aneconomical annual sales rate for a productline (usually for the type of music-pop,contemporary, rhythm and blues) anddeclare all selections that fall short of thesales requirements to be eligible for sale ascut-outs, fully recognizing the legal con-straints spelled out in the contract with theartist. The recommended list of cut-outs,along with the financial impact on the totalbusiness, is furnished to Marketing everyquarter for action. Fig. 4 shows a typicaloutput.

Conceptual modelsfor decision makingAs an extension of the computerizedinventory -management analysis, twomathematical models have been developedto select appropriate strategies for cut-outsales and refurbishment of returns.

The cut-out model predicts current andfuture revenues.

A cut-out decision, in the broadest sense,indicates a preference for a large -quantitysale of a selection now (at very low prices)instead of a series of small- or medium-

SELECTIONNUMBER TITLE

ARL20105ARL20318ARL20371ARL20512ARL20543ARL20637ARL20731ARL20852ARL21104ARL21346ARL21'7'

ARL40370ARL41864

TnscAGRT RecHmmallLA BOHMAT CARNEGIE HALL30 GRT HITS FRM OPERASHANSEL AND OREMSCHUBERT PIANO TRIOSMAHLER STY 82IPHIGE PIEGo m'"

I MORI SICILIAN!LA FORZA DEL DESTINO

AIL, AV NETARTIST DATE SALES

VARIOUS tFERA 7A/11CLIBURN, VAN 78/10LONDON P6IL 0 74/09801E2. JCRGE 74/09VARIOUS OPERA 74/07P OFFO/LUCWIG 74/00AuelNsTEIN, A 75/02CSO/STOKCWSKI 75/11VAR CLASSICAL 75/11"ARIOUS 76/06

'mUS 76/06-.TT 74/06

76/10-ms

ANET P...

VARIOUS OPERA 74/01PRIQWORINGO 73/01

PREFIX CROSS TO!3. HASw.RLS

407 PREFIX 7074

AWL11671 FIFTH AVENUE & CAROL TONNES, CAROL 76/04

PREFIX GROSS TOTXMAS-N-80

4NET PREFIX TOOL

INVENTORY ...PROJECTEDF.G. R.A. 1ST 3 M012ND

I/411800RO DEPLETION.-- OBSOLETE Xs. 8 QTR3 MOIRRO 1 NOIRTH 3 MO !No, 9/8 OvR 4

144781 342 342 97406 132 132 142 10

164 487 497

32 494 96 96 96 96 70

131 223 22142 574 126 126 126 126 70

109 513 314 198

72 641 216 216 10932 773 96 96 96 96 389

98 722 294 294 1)418 3611 94 54 94 54 3399

28 1472 84 04 84 84 1136

421 442 4427$0 1400 1400 NE

082 1028 1021516 916 NE

4.666 5060

3,. 1366 1368 5e.

3756 1364 1368 462 99 357

9 3780 15 14 15 15 5720

5780 19 19 15 15 5720

5780 13 14 15 15 5720

11,44,4

16,5,7

11,1,6

10,57,24,19,862,913,542.1

58,2

381;3

Fig. 3Aging analysis gives projected inventory by artist or selection. Projections, which can be made by historical sales data or interms of breakeven inventory years, are used to make inventory policy decisions.

SELECTIONNUMBER TITLE ARTIST 002

ARS10122 01MIN00 CONDUCTS mILNE COmINGO/PILNS 7)/10ARS10541 GET SONGS SPEC TV OFR BPO/FIEDLER 74/06A010614 G0 57305 TV OFFER 8PO/FIEDLEO 74/07

BUS11823 LOOK AT ME NOW

880101218/0102888451049911010791

BAND 993 WESTTHE LAST SUMMERSKETCHERZAZU

PREFIX GROSS TOPK.MASNwoLS

"'T PREFIX TOTS

BUCKEYE POL,

PREFIX GROSS To!X-MASN-RLS

o NET PREFIX TOOL 1001 1001

REL, COOL!DATE

76/0976/0976/09

6 77/03

INVENTORY OBSOLETEP,G. R.A. INV.

65 6492 9225 24

202 202

202 202

SIEGEL-SCHwAL 7A/10 7009SIEGEL-SCHwAL 74/04 76/09P CDON00060 ME 74/06 76/09ZAZU 75/05 77/03

4

4

2632

2632

REFIX GROSS To; 60 60

x.MAS4-oLS

eNET PREFIX ToTL 60 60

XS. 0 QTRN/R OvR A

,0,0.0

.0

.0

Fig. 4Cut-out analysis identifies products that are no longer profitable and should be dropped from catalog. Outputs can be byselection number (as here) or by artist, type of business contract, or inventory on hand.

quantity sales in the future. Ignoring itsexternal impact, the cut-out decisionattempts to trade the future sales con-tributions and inventory -carrying costsagainst present revenues.

A product's contributions are defined as itssales price less the direct costs involved inselling, such as commissions, royalties, etc.A decision for cut-out sales will be madeonly if their contributions will be greaterthan or equal to all the contributions fromfuture sales and all the carrying cost offuture inventory. Sales taking place in thefuture are discounted to the present value

because of the time value of money. Themodel also accounts for the contributionfrom scrapping the left -over product andthe normal expected rate of return forcapital investment.

The scrap/refurbish model gives thenumber of "breakeven" years for theselections.

In the music business, it is not consideredprudent to store a slow -moving selection inthe hope that it might become a hot sellerwith a change of customer taste and/orartist popularity. Given this, the breakeven

inventory period should be such that thetotal cost of the selection stored is equal tothe value recovered from the selection.

That is, the expression V = Cf + nC1 givesthe breakeven number of years, where Cs isthe annual cost of inventory carrying, n isthe number of years stored, Cf is the cost ofrefurbishment, and V is the value received.Value received could be variously definedas:

Regular sales price - direct costs ofselling including royalty - scrap value,orManufacturing cost - scrap value, or

67

Cut-out sale price - cut-out sale costs -scrap value

Refurbishment costs will be variable,depending upon the extent of refurbish-ment involved.

In every case, a decision to scrap orrefurbish will be preceded by an inquiryinto the breakeven number of years and thedemand for the selection for the breakevennumber of years. If inventory on hand isgreater than the demand during thebreakeven number of years, the selectioncould be summarily scrapped; if lower, itwill be refurbished. The demand during thebreakeven number of years will have to beappropriately forecasted.

A point to be noted in establishinginventory -carrying costs is the relevance ofthe components of the total cost factor. Weare here considering a product alreadymade, where the cost of production is asunk cost. In decision making, therefore,the cost of capital does not enter as afactor-no capital will be released as aresult of this decision (except to the extentof the value of the scrap). The relevantinventory costs, therefore, are only forstorage space, utilities, taxes, etc.

Refinements to the system

The aging -analysis method has been im-proved.

With the breakeven concept introduced inthe scrap/ refurbish model above, it followsthat the selections that have quantities onhand over the requirements during thebreakeven years should be the candidatesfor product pruning through scrapping ordistressed merchandise sales. All the otherswill produce revenues greater than theirinventory -carrying costs and will thereforeproduce net contributions. In the aginganalysis report, selections are arrangedin descending order of the number of yearsthat their inventory on hand can satisfy.Marketing can then identify the cut-outfrom these listings on a qualitative basis.The remaining selections will only producenegative contributions, since theirinventory -carrying costs will be greaterthan the value recoverable from sales.These surplus quantities could be summari-ly scrapped.

Product pruning tells which selectionsshould be dropped from the catalog.

The aging analysis method described abovewill identify selections that could be dis-

continued because of a cut-out or scrapdecision. Selections for which the quantityon hand is not large enough to be identifiedas surplus in the aging analysis will beindividually examined at the time ofreordering. Selections that are steadymovers, selling in medium or largequantities during the year, present noproblem. The others will be analyzed todetermine if the combination of theirordering costs and inventory -carrying costswill produce a net contribution on adiscounted basis. Selections not capable ofmaking any contribution will be dis-continued from the catalog.

Selective processing will make handlingreturns easier.

The refinements in the inventory -management system are scheduled tocoincide with a very significant improve-ment in our returns -handling operations-computerized processing of returnspaperwork on a real-time, on-line basis.This would eventually put the power toscrap or refurbish every returned selectionon a selective basis within our reach. In thissystem, operators processing returns atCRT terminals will be fed with directrefurbish / scrap instructions after keying inthe selection number and the condition ofthe return. The scrap/ refurbish model willbe built into the computer and will make itsdecision based on the on -hand inventoryquantities for that selection.

The benefitsComputerized inventory management hasproved to be a powerful tool in minimizinginventory obsolescence as well as ineconomically disposing of obsolete inven-tory. We have seen the following tangiblebenefits:

I) Statistical sales analysis provides abasis for sales forecasting, with the artistprofile providing the most importantingredient in forecasting new -productsales. The product -life and returnscurves serve as guidelines in forecastingthe sales of products that have been inthe market for several weeks. Correla-tion of early returns with sales producesa useful indicator of the expectedreturns. A measure of the profitability ofproducts released, in terms of units sold,is obtained by analyzing their individualsales and returns performance. Thesystem also identifies the nearly 10% ofthe selections that account for 90% of thenet sales, making them available forsuitable marketing and inventory -management decisions.

2) The three -level inventory turnoverclassification provides a basis for plan-ning investments in inventory andwarehouse space. Monthly computationof inventory turnover provides a feed-back for inventory control.3) The monthly aging analysis reporthighlights inventory obsolescence by in-dividual products. The causes of inven-tory growth can be analyzed on anexception basis to indicate the effect ofsubjective forecasting error, productionand purchase -ordering policies, and in-ventory returns. Aging analysis is thekey method of determining themagnitude of financial reserves for in-ventory obsolescence. In addition, thesystem dictates which selections shouldbe refurbished in the returns process.4) The product cut-out report enables theinventory -management, marketing,business affairs, and financial operationsto judiciously prune products from thecatalog. This is especially importantbecause cut-outs have become anaggressively pursued business practice.

Future developments

Our inventory -management system hasbeen presented in an idealized fashion thatassumes the completion of systems current-ly under development. For instance, themonthly aging analysis results are not yetintegrated with an on-line returns process-ing system to allow selective refurbishmentof returns on an economic basis. In addi-tion, the breakeven computation for theaging -analysis method remains manual.

The current approach of determining thearithmetic average of historical sales foraging analysis has to be replaced with aweighted -average scheme to forecast futuredemands. Also, the sales data base lacks animportant piece of information-the typeand timing of promotional programs. Thisinput will enhance the accuracy of salesforecasting. In addition, normalizing asales curve in terms of the effective productlife remains to be done.

AcknowledgmentsSuccessful computerized inventorymanagement analysis is the result ofMessrs. Corya, Egold, and Veleta, whosework made theories and systems pay realdividends.

Reprint RE -23-3-18This article was originally presented in similar form at theAIIE Systems Engineering Conference, December 1976.

68

Bi-MOS technology produces a universal op amp

H. KhajezadehB.J. Walmsley

Early IC op amps provided the electronicsindustry with a low-cost functionalbuilding block that could be rapidly incor-porated into new equipment designs.Because these devices permitted significantreductions in design time and assemblycosts, they gained universal acceptance,and several types rapidly became industrystandards or commodity items. One suchdevice is the 741, which has been used morewidely than any other operationalamplifier. The rather modest performancecharacteristics of these devices limited theiruse in some applications; however, sinceequipment designers had become ac-customed to using these functional blocks,they simply appended discrete componentsto the ICs to meet system requirements.Thus, for example, discrete MOStransistor pairs were connected at the inputof the standard op amp to improve inputimpedance, and discrete bipolar transistorstages were added to the output to providehigher current drive.

However, IC manufacturers were busydesigning new specialized operationalamplifiers to satisfy the more stringentrequirements. Operational amplifiers withgreater bandwidths were introduced toimprove the transient response, inputstages were designed with super -betatransistors to improve impedance, anddevices were developed for single -supplyapplications. Each new integrated circuitsolved a particular performance problem,but none provided a universal solution.

There is now an op amp, though, the RCACA3I40, that combines many of the per-formance improvements required bydesigners in one device; this new device hasbeen made possible by bi-MOS technology(see box on third page of article). This morerecent op amp has a very low input current,a high slew rate, a wide common -modeinput -voltage range, a wide output -voltagerange, and operates from a single supply inthe range of 4 to 44 V. See Table I forspecifics.

New op amp ICs usually only offer performance im-provements in one particular problem area. Bi-MOS, thesuccessful marriage of two technologies, has produced an opamp that provides improvements in a number of areas.

Device description

This operational amplifier has an open -loop gain of 100,000, as shown in Fig. I.The CA3 I 40 also has the same pin con-nections as the familiar 741. Fig. 2 gives theop amp's schematic.

The input stage consists of a differentialpair of PMOS field-effect transistors withtwo bipolar n -p -n transistors as loads andtwo cascade -connected bipolar transistorsproviding a constant current source of 200µA. Gate protection and offset nullingfeatures are provided. The gain of the firststage is 10. The input current is typically 10

Heshmat Khajezadeh has been Manager ofBipolar Integrated Circuits Engineering atthe Solid State Division since 1974. He hasreceived the David Sarnoff Award for Out-standing Technical Achievement and theRCA Engineering Achievement Award forsignificant contributions to integrated -circuit technology.Contact him at:Bipolar Integrated Circuits EngineeringSolid State DivisionSomerville, N.J.Ext. 6795

pA, because of the MOS input transistors,and the input offset voltage is held toapproximately the same distribution as abipolar differential pair by interdigitatingthe input MOS transistors (Figs. 3 and 4).The second stage uses a bipolar common -emitter transistor with two cascade -connected bipolar transistors as the load. AI 2-pF capacitor on the chip provides com-pensation.

The output stage, which has unity gain,acts as an emitter follower for sourcingcurrent and as a saturated transistor forsinking current. A unique "dynamiccurrent sink" causes the heat -sink current

Bruno Walmsley has 26 years of engineeringexperience, sixteen of them with the SolidState Division. He has worked on all aspectsof testing and test systems development forlinear and digital integrated circuits. He ispresently Manager of Bipolar Applicationsand Test technology at Somerville.

Contact him at:Bipolar Applications and Test TechnologySolid State DivisionSomerville, N.J.Ext. 6199

69

Table ITypical characteristics of the CA3140 atV+ = 30 V and V- = 0 V.

Input currentSlew rateGain bandwidthCommon -mode

input rangeOutput swingOpen -loop gainCommon -mode rejection

ratioOutput current sourceOutput current sink

10 pA9 V/ µs4.5 MHz

-0.5 to +27.5 V0.6 to 27.5 V100 dB

90

2020

dBmAmA

BIAS CIRCUIT INPUT STAGE

021

06

8 n

it D2

INVERTINGNPuT

0-+NON -INVERTING

6Pu7

03

It 05

109 010-

R25000

5000

66SE 7 NULL

R3500 n

SECONDSTAGE OUTPUT STAGE

04

(+)

INPUT

2 mA 4 mA

V 200 'IA

Am 10

®OFFSET

NULL

DYNAMICCURRENT SINK ,it

ty R8

II

014

(86T6, FE

OUTPUT

Fig. 2"Dynamic current sink" after output stage has the current to the sink increaseas the output voltage falls.

CONVENTIONAL, SIDE -BY -SIDE INPUT UNITS

10 20 30 40 50 60 70

INPUT -OFFSET VOLTAGE (VIO)-MILLIVOLTS

BIAS CIRCUITCURRENT SOURCES

AND REGULATOR

X1.6 mA 200µA

A -10,000

CI

12 pF

2µA 2mA

A I

OUTPUT

0 STROBE

Fig. 1

CA3140 has pin connections identical withthe standard 741 op amp.

Fig. 3Interdigitated input MOS transistors are used toapproximate the input offset voltage distributionfound with a bipolar differential pair.

CROSS -PARALLELED, INTERDIGITATED INPUT UNITS

10 20 30 40 50

INPUT -OFFSET VOLTAGE (V/0)-MILLIVOLTS

Fig. 4Good input offset voltage distribution is a result of using interdigitated input transistors.

70

to increase as the output voltage falls. Theoutput stage will sink or source 20 mA ofcurrent and, hence, is capable of drivingcapacitive loads at high slew rates. Theoutput voltages will swing typically towithin 2.5 V of the positive supply voltageand to within 0.6 V of the negative supplyvoltage, with a load of 2

A bias circuit regulates all of the criticalcurrent sources in the amplifier and rendersits characteristics largely independent ofsupply -voltage variations.

ApplicationsThree typical circuit applications for theCA3140-transistor or thyristor driver,current amplifier, and zero -crossingdetector-demonstrate some of its features.

Fig. 5 demonstrates the CA3140's ability toswitch a transistor or thyristor directly,with low VCE sot (0.06 V at 10 µA), whileoperating from a single supply.

Fig. 5Direct thyristor/transistor switchingpossible with this configuration.

10 K

-10 V

What is bi-MOS technology?Bi-MOS is a cost-effective technique for combining MOS and bipolardevices in a monolithic chip without compromising the electricalcharacteristics of either device type. The bi-MOS process requires the samenumber of photosteps as the conventional compensated operational -amplifier process. However, the requirement of the MOS process for a drift -free, low threshold voltage must not be allowed to alter the electricalcharacteristics of the bipolar devices.

The basic bi-MOS process uses (100) crystal, which helps maintain lowlevels of built-in charge and a low p -channel threshold without the need fora special boron implant in the channel areas. Low -temperature HCI andsteam oxidation are used to form the clean, sodium -free channel oxidewithout disturbing the bipolar diffusions. Short-term, high -temperatureannealing reduces the level of built-in charge produced by the low -temperature oxidation.

Aluminum metallization is evaporated in a clean E -gun system to producedevices with maximum threshold stability. The base, emitter, and channeloxide cuts are all tapered to assure reliable metal coverage.

Cross -paralleled interdigitated transistors are used to match the PMOSpairs closely and to assure a low temperature coefficient of input offsetvoltage. Fig. 4 shows how this structure improves input offset -voltagedistribution.

n MOS

n -CHANNEL SOURCEAND SUBSTRATE

LEAD

GATE -METAL LEAD

GATE OXIDE

DRAINLEAD

n+

p- WELL

BURIEDLAYER

p MOS

p - CHANNEL SOURCEAND SUBSTRATE

LEAD

"BOAT"

GATE -METAL LEAD

GATE OXIDEDRAINLEAD

p- SILICON SUBSTRATE

p -nBIPOLAR

EMITTER LEADBASE LEAD

COLLECTOR

EPITAXIALLAYER

Cross section of bi-MOS chip shows CMOS FETs and n -p -n bipolar transistor.

Fig. 6 shows the CA3140 in a current -amplifier circuit measuring very smallcurrents. The CA3140 can be used in this

is application because its input current (10pA) is much lower than the current beingmeasured.

000 M

Fig. 6Current amplifier circuit takes advantage ofCA3140's low input current.

+ VCL

VIN

Fig 7

Zero -crossing detector circuit is based onthe CA3140's single -supply operation; oneinput is used as a ground reference.

This is because the CA3I40 operates from asingle supply, so one of its inputs can beused as a ground reference.

The zero -crossing detector circuit (Fig. 7)senses an input signal and switches theoutput each time the input crosses zero.

SummaryBi-M OS technology has produced a

monolithic operational amplifier, theCA3I40, with significantly improvedcharacteristics. This innovation providesdesigners with an inexpensive monolithicoperational amplifier with the flexibility tobe used in many applications.

Reprint RE -23-3-12Final manuscript received December 12, 1976.

71

ion Qh@c(Dilloff the job

A single -wire alarm system usingthe COSMAC microtutorT.F. Lenihan

Mulitwire alarm systems can easily identifythe entry point in an alarm system, but theyare expensive and installation is complex.Conventional single -wire systems, whileinexpensive and simple to install, cannotpinpoint exactly where the breech hasoccurred. However, by using a series stringof resistors around the perimeter that isbeing protected, and taking advantage ofthe voltage divisions present in such anarrangement, it is possible to detect theexact entry point while retaining the ease ofinstallation inherent in single -wire systems.

HardwareFig. I shows a basic alarm circuit thatcombines ease of installation with theability to locate the entry point. Although itis a single -wire system, the analog/ digital(A/ D) converter can identify the exactlocation where an intrusion takes place.This arrangement uses a resistor/ switchcombination at every door and windowbeing protected. A different value resistoris placed across each switch in a seriesarrangement of switches. When a switch isactivated, a unique voltage is read acrossthe sensing resistor, R, which is shownreturned to ground.

However, I found that this simple arrange-ment works for only about four entrypoints, i.e., four resistor -switch sensors,before the system breaks down. In practice,the string of resistors must be fed by aconstant -current generator. By holding thesource voltage and current to constantvalues, and by varying the resistance alone,the error voltage is developed across theconstant -current source. Now we have asystem that will cover a multitude of entrypoints, albeit one that lacks flexibility. Forexample, entry points intentionally leftopen cannot be ignored in this system. Byadding a microprocessor to the A/Dsystem, this flexibility can be achieved withsoftware. For example, the microprocessorprogram could be written to disregard a

A microprocessor -controlled single -wire burglar alarmsystem gives the user the benefits of standard multiwiresystems, but has additional flexibility and is simpler to install.

+V

16 Rs

MM Mill4 Rs 2 Rs

Fig. 1Simple resistor -switch loop system withonly an A/D converter works as a single -wiresystem, but with limited flexibility.

5 6 12 13

,I ITT=B7B6-B5-1B4 io

B34

3 10

A 8 II

II 1

B1

B0 -12.

MRD

TPB

B

1 1 1 15 6 12 13

1

3

8

II

2

10

+5

61 19

L

1+56

11

2

K

4

7

13

14

4

7

13

14

+5+15 -15

41'T6 19, 120

10

9 228 16

C

7 15

6

5

+511

N2-1NI 21

NB22

233

6A

621D 63

2

619

65

+15

LOOP2LOOP*3

Fig. 3Single -wire alarm system with A/D con-verter plus microprocessor can be ex-panded easily to a multiloop system byhaving the microprocessor poll each loop.

Legend

ComponentK,L - CD4042

A,B - CD4006C - ADC -82D - CD4514

E,F - m A7805H - CD4013

Diodes - 1N91401,02 - 2N6387

dyk.RI

17

26mA 1

CURRENT 240GENERATOR

-15V20k

Hc R S4 _L6

10

9+50-0 R 0 13

33,:f1 o +5

± 33 tif 013310.01Tp.f -ro.oika ZfafTYf

-15

_Le

S30

R300.33kif

ManufacturerRCARCARCA

Burr -BrownRCA

FairchildRCAITT

RCA

+10VREGULATOR2

2N6387

+33µf

BUZZER

5.I V

+15V

Fig. 2Schematic of alarm interface board shows microtutor data bus connections BO -B7,input/output signals NO, N1, N2, and timing control signals MRD and TPB available at theexternal device connector of the COSMAC microtutor. In a multiloop system, only resistor -switches S1 through S30, the constant -current generator, and 10 -volt regulator would needto be duplicated for each loop.

72

window intentionally left open for ventila-tion, or perhaps, for a door under repair.

The circuit shown in Fig. 2 interfacesdirectly with a COS MAC microtutor andwill protect about 30 entry points. Itconsists of a 26-mA constant -current loopmonitored by an 8 -bit A/D converter. Theoutput of the A/ D is latched for input tothe central processing unit. The outputportion consists of a warning buzzer andalarm -bell circuit. The diodes andcapacitors in this section are needed for coilsuppression. The circuit uses one input andfour output strobes decoded by theCD4514. Another application for this cir-cuit is for use as a keyboard. The cost of theA/ D package is $55 in unit quantities. Ishould point out that in the simplest formof the circuit, the microprocessor could bereplaced by hardwired logic. Again,however, the flexibility of the system wouldbe lost.

An expansion of the system organizationfor protecting larger areas is shown inFig. 3 In this multiloop scheme, themicroprocessor sequentially polls severallower -resolution loops. This system willlower costs, because the resistor at eachentry point can have a wider tolerance, andalso improve reliability because cutting onewire will not incapacitate the entire system.

SoftwareFig. 4 is a flowchart of the COSMACmicrotutor program for the burglar -alarmsystem. The circuit is reset immediatelyupon starting and, after a 20 -second delay(to enable you to exit), the program readsthe A/ D latch. To provide a useablemargin between adjacent readings, theinput byte is shifted three times to the right.To protect against random noise spikes, theprogram requires 15 consecutive non -zeroreadings before it advances to the outputmode. In the output mode, the entrancenumber is displayed in hex notation on themicrotutor and the warning buzzer is

activated for 20 seconds. If the "in" switchis not pressed within 20 seconds, the alarmbell is activated. Pressing "in" resets thealarm and restarts the program after a 20 -second delay.

The program activates the warning buzzerto alert you to reset the alarm before thebell goes off (if you are entering) or toindicate to an intruder that a circuit hasbeen tripped before entry has been fullygained. Hopefully, this initial alarm willscare off the intruder.

START )

TOP

RESETBUZZERANDBELL

20 SECONDDELAY

INITIALIZE

START CONVERSIONREAD A/D DISCARDLOWER 3 BITS

RESET

LOOP FLAGTO F0

LOOP FLAG -G0

LOOP FLAG

ALARM FLOWCHART

OUTPUT MODE

OUTPUT CODE,START BUZZER

20 SECONDDELAY

IN PRESSED ?

NO

DELAY DONE?

LONGDELAY

STARTBELL

1 HRDELAY

IN PRESSED ?

DELAY DONE'

Fig. 4Flowchart for single -wire alarm system. Program steps in this chart are detailed in Table II.

Tom Lenihan works in the TV MicrosystemsResearch group at RCA Laboratories. He ispresently involved in applying micro-processors to consumer electronicproducts and automatic testing systems.Tom's idea for a novel way to use RCA'sCOSMAC microprocessor won secondprize in the "COSMAC Applications Con-test," sponsored by Solid State Division in

conjunction with the RCA Engineer. If youare interested in building the systemdescribed in this article and need moreinformation, Tom will be glad to help you.Contact him at:TV Microsystems ResearchRCA LaboratoriesPrinceton, N.J.Ext. 3218

73

START )TOP

RESETBUZZERANDBELL

20 SECONDDELAY

START CONVERSION READ A/D DISCARD

LOWER 3 BITS

RESET

LOOP FLAGTO Fe

LOOP FLAG -00

LOOP FLAG

ALARM FLOWCHART

OUTPUT CODE,START BUZZER

20 SECONDDELAY

IN PRESSED >

NO

DELAY DONE?

YES

STARTBELL

LONGDELAY 141AY

IN PRESSED >

DELAY DONE >

OUTPUT Table IMicrotutor register assignments used in thealarm -system program.

RO = Program counterR3 = Data pointerR4 = Loop flagR5 = Short delay counterR7 = Long delay counter

Delays are based on clock speed of 1.72MHz. Change M004E to vary alarm on -timein 1 -min increments, e.g.:

OA = 10 minOF = 15 min1E = 30 min2D = 45 min3C = 60 min

Table IlaActual alarm -system program is shown infirst set of data below. Second set of data(Table 11b) ties in with flowchart (top left)and shows what event occurs at a particularinstruction byte in that memory location(M).

Memorybyte(M)

Instruction byte(m)

0000 DO E0 61 00 F8 FF B5 A50008 F8 OF FF 01 3A OA 25 95

0010 3A 08 F8 00 B3 F8 FF B50018 A5 F8 67 A3 F8 00 B4 F8

0020 FO A4 E0 62 00 E3 6A FO

0028 F6 F6 F6 53 32 49 84 32

0030 34 14 30 22 E0 63 00 E3

0038 64 23 F8 OF FF 01 3A 3C0040 25 37 01 95 3A 3A 65 30

0048 4D 64 23 30 1C F8 3C A70050 B7 F8 FF A5 B5 F8 2F FF

0058 01 3A 57 25 37 01 95 3A0060 55 27 87 3A 51 30 01

Table Ilb

Algorithm MTop 0001

Reset bell & buzzer 000220 -second delay 0004Initialize 0012Start conversion 0022Read A/D 0026Shift right 3 times 0028Store 002B= 00? 002CIf yes, read again, fix pointer 0020If no, check loop flag 002E= 00? 002FIf yes, go to output mode 0030If no, increment flag, read again 0031

Output mode 0034Start warning buzzer 0035Output code 0037Delay 20 seconds 003AReset? 0041

If yes, go to top 0042If no, continue delay 0043Start bell 0046Go to long delay 0047Output code 0049Go to read again 004BLong delay 004DSet up counters 004EChange value at M004E 0050To vary alarm time 0051

1 -hour delay 0054Decrement counter 005BReset? 005CIf yes, go to top 005DIf no, continue 005EDecrement counter 0061

Done? 0063If no, count again 0064If yes, go to top 0065

Table IIIResistance values for each entry point to be protected in single -wire alarm system.

Resistance Entry Resistance Entryvalue point number value point number

(ohms) (hex readout) (ohms) (hex readout)33 01 390 1047 02 420 11

75 03 440 12

100 04 470 13

120 05 500 14

150 06 530 15

160 07 550 16

200 08 570 17

220 09 600 18

240 OA 630 19

270 OB 660 1A290 OC 680 1B

310 OD 710 1C340 OE 750 1D370 OF 820 1E

74

spgc",x4iimiPIPIWPIOUPIPPIPIPOPPPIPPIMPV

Fig. 5Component side of burglar -alarm interface board shows homebrew L-shaped aluminumbrackets used as heat sinks for the 10 -volt regulator (left) and constant -current generator(near contact side of board). The two transistors in the center are power darlingtons fordriving the bell and buzzer.

Fig. 6Integrated system includes alarm interface board mounted in a microtutor extender boardand connected to a COSMAC microtutor.

Fig. 7Typical installation of resistor switches throughout a house in a single -wire alarm system.Magnetic switches, if used, should be of the normally open type.

The bell will reset and re -arm automaticallyone hour after going off, so that if you areaway for an extended period, the bell willnot ring continuously until you return. Anotice to this effect should be postedconspicuously for the police.

The software for implementing thisprogram is shown in Tables I and II. Thesoftware was written to accommodate boththe CDP1801 and the CDP1802 versions ofthe microtutor. If the CDP1801 version isused, change the 64 instructions at M(0038)and M(0049) to 60.

The code 00 is the normal closed -loopreading. Any other reading indicates abreech of the system. The unique code IFindicates that the system wire has been cut.

Construction hintsThe ±15 -volt power supplies to the A/ Dconverter should be bypassed as close tothe package as possible and the IAA 7805regulators should be installed with a smallheat sink attached as shown in Fig. 5. Theoriginal board was wire -wrapped on aVector plugboard for direct insertion intothe microtutor external socket. A laterversion (Fig. 6) used a microtutor extenderboard. If magnetic switches are used, theyshould be of the type which are normallyopen (contacts apart). Using the resistancevalues shown in Table II, the unit willmonitor 30 doors and windows, a combina-tion covering most houses. All values inTable III were determined using standard5% resistors. Fig. 7 shows a typical installa-tion of switches throughout a house.

Reprint RE -23-3-19Final manuscript received November 10, 1977.

75

Dates and DeadlinesUpcoming meetings

Ed. Note: Meetings are listed chronological-ly. Listed after the meeting title (in bold type)are the sponsor(s), the location, and theperson to contact for more information.

DEC 5-7, 1977 - Natl. TelecommunicationsConf. (IEEE et al) Marriott Hotel, LosAngeles, CA Prog Info: Stanley A. Butman,4800 Oak Grove Dr., Pasadena, CA 91103

DEC 5-7, 1977 - International ElectronDevices Mtg. (IEEE) Washington Hilton,Washington, DC Prog Info: CourtesyAssoc./Susan Henman, 1629 "K" St., NW,Washington, DC 20006

DEC 5-7, 1977 - 1977 Winter SimulationConf. (IEEE) Natl. Bureau of Standards,Gaithersburg, MD Prog Info: R.G. Sargent,Dept. of Industrial Eng. & OperationsResearch, Syracuse Univ., Syracuse, NY13210

DEC 15, 1977 - Computer Networks:Trends & Applications (IEEE, NBS) Natl.Bureau of Standards, Gaithersburg, MDProg Info: Computer Networks, PO Box 639,Silver Spring, MD 20901

JAN 16-18, 1978 - Integrated & GuidedWave Optics (IEEE, OSA) Salt Lake Hilton,Salt Lake City, UT Prog Info: Amnon Yariv,Calif. Institute of Tech., Pasadena, CA 91109

JAN 24-26, 1978 - Reliability & Main-tainability (IEEE et al) Biltmore, LosAngeles, CA Prog Info: D.F. Barber, PO Box1401, Branch PO, Griffiss AFB, NY 13441

FEB 7-9, 1978 - Laser and Electro-OpticalSystems II (IEEE, OSA) Town and CountryHotel, San Diego, CA Prog Info: Jon Hagan,Optical Society of America, Suite 620, 2000"K" St., NW, Washington, DC 20006

FEB 13-15, 1978 - WINCON (Aerospace &Electronic Systems Winter Convention)(IEEE) Los Angeles, CA Prog Info: Max T.Weiss, The Aerospace Corp., PO Box 92957,Los Angeles, CA 90009

FEB 15-17, 1978 - Intl. Solid State CircuitConf. (IEEE, U. of Penn.) Hilton, SanFrancisco, CA Prog Info: Mark R. Barber,Bell Labs., 600 Mountain Ave., Murray Hill,NJ 07974

MAR 21-28, 1978 - Industrial Applicationsof Microprocessors (IEEE) Sheraton,Philadelphia, PA Prog Info: W.W. Koepsel,Dept. of E.E., Seaton Hall, Kansas StateUniv., Manhattan, KS 66505

MAR 22-24, 1978 - Vehicular TechnologyConf. (IEEE) Regency Hotel, Denver, COProg Info: John J. Tary, U.S. Dept. ofCommerce, OT/ITS, 325 Broadway,Boulder, CO 80302

APR 3-7, 1978 - Design Engineering Conf.and Show McCormick Place, Chicago, ILProg Info: Tech. Affairs Dept., ASME, 345East 47th Street, United Engrg. Ctr., NewYork, NY 10017

APR 4-6, 1978 - Private ElectronicSwitching Systems Intl. (IEEE, IEE) IEE,London, England Prog Info: IEE Conf. Dept.,Savoy Place, London WC2R OBI, England.

APR 4-7, 1978 - Communications '78 (Intl.Exposition of Communications Equipment& Systems) Birmingham, England Prog Info:Exhibition Director, Tony Davies Com-munications, c/o Industrial & Trade FairsLtd., Radcliffe House, Blenheim Court,Solihull, West Midlands B91 2BG, England

APR 10-12, 1978 - Acoustics, Speech andSignal Processing (IEEE) Camelot Inn,Tulsa, OK Prog Info: Rao Yarlagadda,School of Elect. Engineering, OklahomaState Univ., Stillwater, OK 74074

APR 24-26, 1978 - Electronic Components(IEEE, EIA) Disneyland, Anaheim, CA ProgInfo: John Powers, Jr., IBM Corp. Hdqtrs.,Dept. 836 IB, 43 Old Orchard Rd., Armonk,NY 10504

MAY 10-12, 1978 - Conf. on SoftwareEngrg. (IEEE, NBS) Hyatt Regency Hotel,Atlanta, GA Prog Info: Harry Hayman, Conf.on Software Engrg., PO Box 639, SilverSpring, MD 20901

MAY 16-18, 1978 - NAECON (NationalAerospace & Electronics Conf.) (IEEE)Dayton Convention Ctr., Dayton, OH ProgInfo: NAECON, 140 E. Mounument Ave.,Dayton, OH 45402

MAY 17-19, 1978 - Circuits & Systems Intl.Symp. (IEEE) Roosevelt Hotel, New York,NY Prog Info: H.E. Meadows, Dept. of Elec.Engineering & Computer Science,Columbia Univ., New York, NY 10027

MAY 23-25, 1978 - Electro/78 (IEEE)Boston -Sheraton, Hynes Auditorium,Boston, MA Prog Info: W.C. Weber, Jr., IEEEElectro, 31 Channing St., Newton, MA 02158

Calls for papers

Ed. Note: Calls are listed chronologically bymeeting date. Listed after the meeting (inbold type) are the sponsor(s), the location,and deadline information for submittals.

May 1-3, 1978 - Microwave Power TubeConf. (IEEE, DOD) Naval PostgraduateSchool, Monterey, CA Deadline Info: (ab)2/1/78 to Leonard H. Klein, Palisades In-stitute for Research Services, Inc., 201Varick St., New York, NY 10014

MAY 17-19, 1978 -1978 Carnahan Conf. onCrime Countermeasures (IEEE, U. of Ken-tucky) Carnahan House, Lexington, KYDeadline Info: 1/16/78 to John S. Jackson,College of Eng., U. of Kentucky, Lexington,KY 40506

MAY 29 -JUN 1, 1978 - Intl. QuantumElectronics Conf. (IEEE, AI P) Atlanta Hilton,Atlanta, GA Deadline Info: (35-wd ab and500-wd sum) 1/2/78 to Optical Society ofAmerica, IQEC X, Suite 620, 2000 L St., N.W.,Washington, DC 20036

JUN 20-22, 1978 - Pulse Power ModulatorSymp (IEEE et at) Statler Hilton, Buffalo, NYDeadline Info: (ab) 3/10/78 to LeonardKlein, Palisades Institute for ResearchServices, Inc., 201 Varick St., New York, NY10014

JUN 26-29, 1978 - Conf. on PrecisionElectromagnetic Measure (IEEE, URSI/USNC) Conf. Ctr., Ottawa, Ont. DeadlineInfo: (ab & summary) 1/15/78 to Dr. AndrewF. Dunn, Natl. Research Council, MontrealRoad, Ottawa, Ont.

JUL 16-21, 1978 - Power EngineeringSociety Summer Mtg. (IEEE) Los Angeles,CA Deadline Info: 2/1/78 to G.A. Davis,Southern Box 800,Rosemead, CA 91770

SEP 12-14, 1978 - AUTOTESTCON(Automatic Support Systems for AdvancedMaintainability) (IEEE) San Diego, CADeadline Info: 4/15/78 to Bob Aguais,General Dynamics, Electronic Div., M.S. 7-98, PO Box 81127, San Diego, CA 92138

OCT 1-5, 1978 - Industry ApplicationsSociety Conf. (IEEE) Royal York Hotel,Toronto, Ont. Deadline Info: 3/7/78 to HarryPrevey, 4141 Yonge Street, Willowdale, Ont.M2P 1N6

OCT 9-11, 1978 - Semiconductor LaserConf. (6th) (IEEE) Hyatt Regency Hotel, SanFrancisco, CA Deadline Info: 6/15/78 to T.L.Paoli, Bell Laboratories, 600 Mountain Ave.,Murray Hill, NJ 07974

OCT 11-12, 1978 - 3rd Specialist Conf. onTech. of Electroluminescent Diodes (IEEE)Hyatt Regency Hotel, San Francisco, CADeadline Info: 6/15/78 to R.N. Bhargava,Phillips Lab., Briarcliff Manor, NY 10510

NOV 7-9, 1978 PLANS '78 (Position Loca-tion & Navigation Symp.) (IEEE) San Diego,CA Deadline Info: 5/15/78 to Nelson Har-nois, Cubic, PO Box 80787, San Diego, CA92138

DEC 4-6, 1978 - Natl. TelecommunicationsConf. (IEEE) Hyatt Hotel, Birmingham, ALDeadline Info: 5/78 to H.T. Uthlaut, Jr.,South Central Bell, PO Box 771,Birmingham, AL 35201

76

Pen and Podium Recent RCA technical papers and presentations

To obtain copies of papers, check your library or contact the author or his divisional Technical Publications Administrator(listed on back cover) for a reprint. For additional assistance In locating RCA technical literature, contact RCA TechnicalCommunications, Bldg. 204-2, Cherry Hill, N.J., extension PY-4256.

Advanced TechnologyLaboratoriesD.A. Gandolfo' D.B. SteppsA. Boornardl E.P. Herrmann' J.R. TowerGigabit recorder readout experiments withintegrated photosensors-Proc. Electro-Optics/Laser '77 Conf. & Expo., Anaheim,CA (10/26/77)

W.F. Heagertyl H.W. KaiserClosed geometry CMOS/SOS structures forlinear and radiation hardened appli-cations -1977 IEEE SOS Workshop, Vail,CO (9/28/77)

R.F. KenvilleOptical video disc for high rate digital datarecording-Proc. Electro-Optics/Laser '77Conf. & Expo., Anaheim, CA (10/26/77)

A. MerriamIndustry support-PRIME Local Workshop,Villanova U., Phila., PA (8/24/77)

A. MerriamVideo monitor microcomputer demon-stration-PRIME Local Workshop, VillanovaU., Phila., PA (8/25/77)

S. OzgaCMOS/SOS microprocessor for militaryapplications-Seminar on ImprovingUtilization of Advanced IC Technology,IDA, Arlington, VA (8/9-11/77)

S.E. OzgaCMOS/SOS processor-AIAA Computersin Aerospace Conf., Los Angeles, CA(10/31/77)

P. Ramondettal J. SmileyA design automated approach for complexCMOS LSI hybrid substrates-ElectronicScience, Vol. 27 No. 11 (10/77) pp. 77-81

J. Saultz' A. FellerApproaches to developing and utilizing LSIin military equipment-Seminar on Im-proving Utilization of Advanced ICTechnology, IDA, Arlington, VA (8/9-11/77)

J. Schannel B. SchamingJ. Rudnick' G. Claffiel J. RichardsA digital real time intraframe videobandwidth compression system-SPIESymp., San Diego, CA (8/25/77)

R.D. Scott' E.W. Schliebenl T.D. MichaelisMechanical capacitor-Proc. 1977 FlywheelTechnology Symp., San Francisco, CA(10/5-7/77)

Automated SystemsB.R. Clay' W.J. Hannan' M.T. Gale' K. KnopEmbossed holograms-Electro-Optics/

Laser '77 Conf. & Expo., Anaheim, CA(10/26/77)

R.F. GerenzData fusion-Electronics in NORAD Symp.,AF Academy, Colorado Springs, CO (9/13-15/77)

M.L. JohnsonProduct support-Society of LogisticsEngineers (10/6/77) Wenham, MA

D.M. Priestley' R.P. PercoskiNew technology automatic test systemsimplifies maintenance interface withARTADS-ACFEA Seminar, Ft. Monmouth,NJ (9/15/77)

GlobcomM.E. LogiadisInternational field tests of digital facsimileequipment-CCITT Study Group (11/14-18/77)

GovernmentCommunications SystemsR.Buskirkl E.J. NossenECM/ECCM effects on voice transmission-Proc., Intl. Telemetering Conf., Los Angeles,CA (10/18-20/77)

C. Haber' E.J. NossenPseudo -random code sidelobe canceller-Proc., Intl. Telemetering Conf., Los Angeles,CA (10/18-20/77)

D. Hampell C.W. GwinnPolynomial array techniques in forecasting,prediction and recognition-Proc., 1977Intl. Conf. on Cybernetics & Society,Washington, DC (9/20/77)

M. Nguyen' R. PickholtzBounds for the queue in loop system-Intl.Symp., Performance on Queuing System,Ithaca, NY (10/10/77)

E.J. NossenThe Apollo VHF ranging system-Proc., Intl.Telemetering Conf., Los Angeles, CA(10/18-20/77)

E.J. NossenCommunications in a counter-measuresenvironment-Conf. Record, INTELCOM'77, Atlanta, GA (10/12-14/77)

E. Nossen1C. HaberLow cost pseudo noise modem-Conf.Record, INTELCOM '77, Atlanta, GA (10/12-14/77)

V. VolertasIE.J. NossenPhase modulation techniques for digital

communication systems-Conf. Record,INTELCOM '77, Atlanta, GA (10/12-14/77)

GovernmentSystems DivisionJ. HilibrandCustom CMOS LSI for military systems-Seminar on Improving Utilization of Ad-vanced IC Technology, IDA, Arlington, VA(8/9-11/77)

LaboratoriesA. Bloom' P.L.K. HungThe effect of dye structure on orderparameter in a nematic liquid crystallinehost-Molecular Crystals Liquid Crystals,Vol. 40 (1977) pp. 213-221

I. Haltal W. RehwaldSpecific heat of SnxGei-xTe crystals nearthe structural phase transition-J. Physics,Vol. C10, No. 12 (7/28/77) pp. 2075-81

J.I. Pankovel D.E. CarlsonPhotoluminescence of hydrogenatedamorphous silicon-App/. Physics Lett.,Vol. 31 No. 7 (10/1/77) p. 450

S. Roth' W. Rehwaldl H. MallieAcoustic soft modes of Nb3Sn In highmagnetic fields-Solid State Com-munications, Vol. 22 No. 3 (4/77) pp. 177-79

W. Rehwaldl J.R. Sandercocki M. RossinelliElastic properties of KCN and K(CN) 1-x Clx- Physics Status Solidi, Vol A42, No. 2(8/16/77) pp. 699-705

H.S. Sommers, Jr.' H.F. LockwoodOptical absorption coefficient of(A1.42Ga.58)As-J. Appl. Physics, Vol. 48No. 9 (9/77) p.4000

P.K. WeimerThin-film transistors in integrated circuits-present status and prospects-Conf.Record, Intl. Conf. on Thin- and Thick -filmDevices, Augsburg, Germany (9/28-30/77)pp. 133-35

Missile and Surface RadarJ.A. BauerUse of chip carriers for high packagingdensity, high reliability, high performanceproducts- Proc., NEPCON '77 (9/77) p. 50

E. DixonMicrowave engineering today-Natl.Science Foundation, Temple U., Phila., Pa.(9/25/77)

77

B.P. Gaffney' J.N. GowdyA symmetry relationship for "between"scaling-IEEE Trans. on Acoustics, Speech,and Signal Processing, Vol. ASSP-25 No. 4(8/77)

S. HalpernThe assurance sciences-an introduction toquality control and reliability-PrenticeHall, Inc. (10/77)

V.W. Hammond' J.W. BornholdtRange instrumentation radar systems-Military Electronics Defense Expo '77,Wiesbaden, West Germany (9/27-29/77)

E.G. LurcottPD2, a system management tool-DefenseSystems Management Review, Vol. 1, No. 4(Autumn 1977) pp. 19-28

V. MangulisAn approximation for diffraction by a cir-cular cylinder-Microwave Journal, Vol. 20,No. 9 (9/77) p. 72

L.W. Martinson' J.A. LunsfordCMOS/SOS technology and its applicationto digital signal processing- Proc.,EASCON 1977, Washington, DC (9/26-28/77)

G.J. MayerExperimental results of a programmableanalog -weight CCD convolver and someunique radar applications-Intl. Electrical,Electronics Conf. and Expo., Toronto, Ont.,(9/26-28/77)

G.J. Mayer] B.P. GaffneyModel and simulation of charge -coupleddevices for signal -processing analysis -1977 Intl. Electrical, Electronics Conf. andExpo., Toronto, Ont. (9/26-28/77)

F. ReiflerThe optimal orthogonal control law formaximizing terminal missile speed-SIAM,Albuquerque, NM (10/31/77)

R.J. SmithA bit -slice module set for microcomputing-COMPCON '77 Fall, Washington, DC (9/6-9/77)

L. WeinbergScheduling multifunction radar systems-Proc., EASCON '77, Washington, DC (9/6-9/77)

RCA Service Co.L.E. Mertens' F.S. Replogle, Jr.Use of point spread and beam spreadfunctions for analysis of Imaging systems inwater-J. Optical Soc. Amer. (8/77)

R.E. Taylor' J.S. HillAirborne urban/suburban noisemeasurements at 121.5/243 MHz-Record,1977 Intl. IEEE Symp. on ElectromagneticCompatibility, Seattle, WA (8/3/77)

Patents

Advanced TechnologyLaboratoryW.F. Heagerty] L. Dillon, Jr.Edgeless transistor -4054894 (assigned toU.S. Government)

Avionics SystemsW.L. RossMulti -target tracker for tracking near co -range targets -4052721

Broadcast SystemsW.J. Derenbecher, Jr.PAL four -frame subcarrier phase detector -4052733

P.J. SchmalzHelical resonator -4052684

Consumer ElectronicsL.A. CochranHue correction apparatus controlled bychrominance saturation -4051510

L.A. HarwoodPhase control circuit suitable for use in a tintcontrol stage of a color television system -4051519

L.A. HarwoodVideo amplifier for combining luminanceand chrominance signals -4051521

L.A. Harwood' E.J. WittmannAutomatic chrominance gain controlsystem -4054905

G.K. SendelweckBurst gate pulse generator -4051518

GovernmentCommunications SystemsP.J. AnzaloneLow noise amplifier -4035738 (assigned toU.S. Government)

L.P. NahaySolid state two-wire/four-wire converterwith common battery -4053722 (assignedto U.S. Government)

GovernmentSystems DivisionE. JellinekHeading sensor for vehicle dead reckoningsystem -4055750

LaboratoriesR.A. Bartolinil A. BloomOrganic medium for thin -phaseholography -4055423

J.C. Bleazey1M.A. LeedomStylus arm lifting/lowering apparatus for avideo disc player -4053161

A. Bloom' R.A. BartoliniOrganic volume phase holographicrecording medium -4049459

W.J. Burke' P. ShengRecording a phase hologram havingreduced intermodulation distortion -4054358 (assigned to U.S. Government)

C.R. CarlsonAnalog optical block processor -4045133(assigned to U.S. Government)

A.S. ClorfeineBi-static radar speed sensor -4050071

A.G. DingwallMethod of making a semiconductordevice -4045250

A.G. DingwallSemiconductor integrated circuit device in-cluding an array of insulated gate field effecttransistors -4045811

M. Ettenberg' H.F. LockwoodElectroluminescent semiconductor devicehaving a restricted current flow -4048627

A.M. GoodmanCapacitance meter bias protection circuit -4050018

P.E. HaferlSwitched vertical deflection system -4048544

W.E. HamSilicon -on -sapphire mesa transistor havingdoped edges -4054895

K.W. HangGlass frit composition for sealing windowglass -4049872

G.B. HerzogCombined controlled oscillator and fre-quency multiplier -4052673

R.J. HimicsIN.V. Desail E.S. PoliniakMethod of transferring a surface reliefpattern from a poly(olef in sulfone) layer to ametal layer -4045318

R.J. Himicsl S.O. Graham' D.L. RossPhotosensitive copolymer on siliconsupport -4054454

S.T. HsuComplementary field effect transistoramplifier -4045747

S.P. KnightUhf tuning circuit utilizing a varactordiode -4048598

78

S.P. Knighti T.E. MolinariPlanar printed circuit board arrangementuseful in the uhf portion of a televisiontuner -4048597

I. LadanyLight emitting diode having a short transientresponse time -4049994

H.P. LambertSimultaneous location of areas havingdifferent conductivities -4046606

M.A. LeedomPickup cartridge -4049280

H.F. Lockwood' M. EttenbergLiquid phase epitaxial growth with inter-facial temperature difference -4052252

G.S. Lozieri P.B. BraninMethod for preparing filter -coated phos-phor particles -4049845

M.J. LurieProviding a representation of Informationstored in a hologram -4054357

G.H. Olsen) V.S. BanMethods of defining regions of crystallinematerial of the group Ill -V compounds -4053350

J.A. RajchmanApparatus and method for modulating a fiatpanel display device -4051468

A. Roseni L.S. NapoliMicrowave frequency discriminator com-prising an FET amplifier -4053841 (assign-ed to U.S. Government)

B.D. RosenthalComparator circuit -4047059

B.D. RosenthalCurrent subtractor-4055812

B.D. Rosenthali A.G. DingwallCircuit for starting current flow in currentamplifier circuits -4051392

W. Rosnowskii S. PonczakMethod of selective aluminum diffusion -4050967

R.G. StewartPower -on reset circuit -4045688

A.V. Tumai J. SchiessFrequency doubler -4052626

Z. Turskil D.D. MawhinneyMicrowave frequency discriminator com-prising an FET amplifier -4053842(assigned to U.S. Government)

P.K. WeimerCharge transfer readout circuits -4055836

C.E. WeitzelMethod of etching sapphire utilizing sulfurhexafluoride-4052251 (assigned to U.S.Government)

C.F. Wheatley, Jr.Adjustable gain current amplifiers -4045746

C.F. Wheatley, Jr.Transistor amplifiers -4051441

C.F. Wheatley, Jr.Transistor amplifiers -4055811

B.F. Williamsi D.L. StaeblerW.J. Burkei W. PhillipsCrystals for recording phase holograms -4052119 (assigned to U.S. Government)

Picture Tube DivisionD.E. GriesemerCathode-ray tube screening exposuremethod -4052725

H.B. LawMethod for forming a color television picturetube screen -4049451

E.M. NekutReverse -printing method for producingcathode -ray -tube screen -4049452

E.S. ThallMethod for assembling a thermally -setgetter spring in a CRT -4045849

SelectaVision ProjectT.F. KirschnerStylus cleaning system for disc recordplayer -4046384

Solid State DivisionA.A. AhmedCurrent divider -4045694

A.A. AhmedCurrent -operated circuits and structures -4051391

A.A. AhmedCurrent scaling apparatus -4055774

A.A. AhmedMonostable switching circuit -4047057

A.A. AhmedThyristor switching circuit -4047054

M. Glogoljai C.B. LeuthauserTransient and thermal protection -4054845

L.F. Heckman, Jr.Radio frequency coupler -4051447

J.S. RadovskyPhase-splitter-4049977

O.H. Schade, Jr.Ground fault interrupter apparatus -4045822

J.P. White) P.J. KannamHigh voltage semiconductor device having anovel edge contour -4047196

RCA plansFinite Element Symposium-papers invited

Finite -element computer methodsprovide powerful ways of solvingengineering problems. These methodshave been applied, for example, indetermining stress distributions insatellites and tv picture tubes, naturalfrequency of vibration in antennas, heatflow in large electron tubes, and strengthof silicon wafers. This work is presentlybeing carried out in at least four differentRCA locations.

Accordingly, a symposium is beingplanned to let engineers hear formalpresentations, meet to discuss mutualproblems, and introduce finite -elementmethods to those who have not yet had"hands-on" experience with them.

RCA engineers and scientists who haveused finite element methods or whowould like to learn about the use of thesemethods are invited both to attend andpresent papers. Publication of papersthat are not proprietary is planned in theRCA Review.

Here are the details of the conference: Date: March 13 and 14, 1978 Place: RCA Laboratories, Princeton,

N.J. Expression of interest and possible title

of presentation by January 15, 1978 Deadline for abstract: February 15,

1978 Deadline for manuscripts of papers for

publication: March 15, 1978

Please send abstracts/papers/expres-sions of interest to any one of the follow-ing committee members:R. E. Enstrom, Chairman (RCA

Laboratories, Princeton, N.J.)R.C. Bauder (Picture Tube Division, Lan-

caster, Pa.)W.W. Metzger (Astro Electronics,

Princeton, N.J.)R. Pschunder (Missile & Surface Radar,

Moorestown, N.J.)A.W. Sheffler (Astro Electronics,

Princeton, N.J.)B.P. Wang (Astro Electronics, Princeton,

N.J.)

79

Engineering News and HighlightsWright, Shashoua, Ross have new jobs in GSD

Paul E. Wright was appointed Division VicePresident, Engineering, for GovernmentSystems Division, Moorestown, N.J. He isresponsible for coordination of engineeringactivities for GSD's four business units:Astro-Electronics, Automated Systems,Government Communications Systems,and Missile and Surface Radar. For the fiveyears preceding this promotion, Mr. Wrightwas Director, Advanced TechnologyLaboratories. Since joining RCA in 1958, hehas held positions as Manager, AppliedPhysics and Mechanics; Manager, Ad-vanced Mechanical Technology, and otherengineering posts with the Laboratories.

Licensed engineers

When you receive a professional license,send your name, PE number (and state inwhich registered), RCA division, location,and telephone number to: RCA Engineer,Bldg. 204-2, RCA, Cherry Hill, N.J. Newlistings (and corrections or changes toprevious listings) will be published in eachissue.

RCA AmericanCommunications, Inc.Paul W. DeBaylo, Piscataway, N.J.; Cal.-QU2047.

Astro-Electronics

Fred E. Shashoua was appointed Director,Advanced Technology Laboratories,Government Systems Division. He willmanage research and developmentactivities at ATL, Camden. Joining RCA in1956 as an electronics engineer, Mr.Shashoua has held jobs as Leader,Recording Systems Development; Manager,Advanced Recordings and Displays;Manager, Advanced TechnologyLaboratory, Burlington; and most recentlyManager, Electro-Optical Systems,Automated Systems.

GovernmentCommunications SystemsHarold A. Brill, Camden, N.J.; NJ -24489.

RCA RecordsCharles A. Weaver, Indianapolis, Ind.; IN -17205.

Solid State DivisionCory C. Williams, Findlay, Ohio; IN -14914;OH -014667.

Ernest D. Scaran, Mountaintop, Pa.; PA -26505 -E.

Albert L. Goldsmith, Princeton, N.J.; Cal.- Salvadore P. Barlett, Mountaintop, Pa.; PA-QU2379. 26487-E.

Dr. Sidney Ross was appointed StaffTechnical Advisor for Government SystemsDivision. He is responsible for independentresearch and developMent within the Divi-sion. He was Technical Director, FrankfordArsenal, Philadelphia, since 1968. He joinedFrankford Arsenal in 1948 as a ProjectEngineer in the Physics and EngineeringDepartment. Dr. Ross received the BS fromPennsylvania State University, the MS fromthe University of Pennsylvania and the PhDfrom Temple University-all in physics. Hedid post doctoral work at Princeton Uni-versity and the University of California atLos Angeles. He is a registered professionalengineer in Pennsylvania. A recipient ofmany government honors, Dr. Rossreceived the Department of the Army Out-standing Performance Award in 1965 andagain in 1976. He is a member of Sigma PiSigma, the national physics honor society;American Institute of Physics, AmericanPhysical Society, Scientific Research Socie-ty of America and the Optical Society ofAmerica.

Degrees grantedMobile CommunicationsSystemsWilliam G. Stewig-MBA, University ofPittsburgh.

Solid State DivisionWallace D. Williams-MS, Physics; RutgersUniversity.

80

Nine technical excellence award winners at MoorestownMaurice Breese-for technical creativityand leadership in developing a diode phaseshifter concept for advanced arrayapplications.

Girard Goldkrantz-for personal initiativeand technical competence demonstrated indesign of the two AN/SPY-1A Moving TargetIndicator cabinets.

Doug Perham-for creative and resourcefuldesign effort in the successful modificationof the Haystack Long -Range Imaging Radar(LRIR).

Frank Reifler-for outstanding achievementin the design of filters and related algorithmsfor AEGIS, and for important contributionsto filter theory.

Bob Sharp-for his timely and imaginativeapplication of high-level functional analysisin support of design of the AEGIS ShipCombat Information Center.

Vic Stachejko-for his conceptual creativityin the development of a microwave phasemodulator in integrated circuit form, ex-hibiting unprecedented accuracy over anoctave bandwidth.

Three key members of the AEGIS AN/SPY-1A Signal Processor test team were honoredfor their achievements in the successful testand qualification of this very complexsystem in less than six months (less thanone-half the time taken for the EDM-1 SignalProcessor):George Oakes-for his special con-tributions as Senior Project Engineer duringtne checkout and performance qualificationtesting.

Bob Peterson-for his special contributionsas the program's Systems Test Engineer.

Harry Ulrich-for his technical leadershipand direction of the engineering test teamresponsible for qualification of the SignalProcessor.

Four cited at Astro-ElectronicsA new method for producing welded -wirecircuit -board documentation won a

Technical Excellence Team Award for fourengineers at Astro-Electronics. The newtechnique developed by award winners Tom

Murphy, Bill Mulrooney, Doug Milke, andJoe Scaven has proven to be more efficientand accurate than the previous manualmethod system.

Ten win TE award at Automated Systems

Test system development work led to a team award for ten engineers at Automated Systemsin Burlington, Mass. In the photo, left to right, are H.J. Woll, Div. V.P. and General Manager;team members B. Ballard, R.M. Carner (seated), D.L. Boudreau, C.F. Sullivan, M.F. LeVarn,J.P. Godfrey (seated), and M.H. Strong; Project Manager, W.R. Wadden; team members S.P.Patrakis (seated) and J.H. O'Connell; Manager Data Systems Development, A.F. Dirsa;Chief Engineer, E.M. Stockton; team member J.M. Goode (seated); and Manager ofCommand and Control Programs, E.O. Seaborn.

Perham

Sharp

Ulrich

Mulrooney

Scaven

Goldkrantz

Reifler

do.Stacheiko

Peterson

Murpl. y

Milke

81

Obituaries

Dudley M. Cottler, Staff Technical Advisor,Government Engineering, GSD, died Oc-tober 10, 1977.

He joined RCA in 1956 and held severalengineering management positions in-volving the design, development, produc-tion, and testing of radar systems. He wasChief Engineer of the Missile and SurfaceRadar Division from 1967 to 1974. Duringthat time the division made important ad-vances in radar and systems technology,ranging from such major systemsdevelopments as AEGIS and AN/FPS-95 tosuch critical concept developments as ultra-high -speed digital design for advanceddata/signal processing systems. In his mostrecent job, Mr. Cottler was responsible forthe Independent Research and Develop-ment Program for all of the GovernmentSystems Division's government contracts-administering the fields of investigation andthe allocation of funds for the program.

W.Walter Watts, a former senior officer andDirector of RCA, died November 15. Heretired from RCA as an Executive VicePresident in May 1970, but continued toserve on the company's Board of Directorsfor another year.

Mr. Watts joined RCA in 1945 after wartimeservice as a Colonel and CommandingOfficer of the Signal Corps DistributionAgency..He was elected a Vice President ofRCA in 1946 and Executive Vice President,Electronic Products, in 1954. He becameExecutive Vice President, Electronic Com-ponents, in 1955, and Group Executive VicePresident in 1958. He was Chairman of theRCA Sales Corporation and the the RCAVictor Distributing Corp. from 1960-64. Hebecame Senior Executive Vice President,Defense and Commercial Systems, in 1968.

Recent books by RCA authors

The Assurance Sciences-An Introduction to QualityControl and Reliability

Sigmund HalpernPublished by Prentice -Hall Inc.[448 pp, $16.95]

Author Halpern joined RCA Camden in 1951as a design engineer. He later transferred tothe reliability department at Astro Elec-tronics, where his responsibilities asengineering leader involved many reliabilitytasks on space programs. Since 1970 he hasbeen associated with MSR's. Technical

Assurance Department. He provided us withthe following description his book.

This book is designed to fill a void in most oftoday's engineering curricula-the nearlytotal absence of courses in the assurancesciences. The lack of attention paid to thefields of quality control, reliability, main-tainability,and integrated logistic engineer-ing often becomes evident when a graduateis hired by an aerospace or defense con-tracting firm. Commercial manufacturersare also becoming increasingly interested inthe potential benefits that more organizedreliability and maintainability disciplinescould offer them.

Because the book is a comprehensive in-troductory text that develops a workingknowledge of the assurance scienceswithout prior experience, it is ideally suitedfor use in engineering colleges andtechnical institutes. A helpful feature is theinclusion of pertinent portions of govern-ment and military specifications and stan-dards and the demonstration of their use inmany of the practical problems solved.

The book should be equally valuable as anon-the-job training tool for engineers,managers, and technicians exposed tothese fields.

Vollmer is President,Philadelphia Chapter NSIADr. James Vollmer, Division Vice Presidentand General Manager, GovernmentSystems Division, was elected President ofthe Philadelphia Chapter, National SecurityIndustrial Association. NSIA is a nationwideorganization of industry representativesadvising government on technologicalmatters concerning national security.

Rajchman receivesPender AwardDr. Jan A. Rajchman, retired Staff VicePresident, Information Sciences, RCALaboratories, received the University ofPennsylvania's Pender Award for dis-tinguished engineering contributions. Theaward was presented to him on October 28at the annual dinner meeting of Penn'sEngineering Alumni Society.

Promotions

Consumer ElectronicsPaul L. Vos from Junior Member, Engineer-ing Staff, to Regional Training Manager.

Solid State DivisionJorgan F. Nielsen, from Member, TechnicalStaff, to Leader, Technical Staff.

Picture Tube DivisionWalter R. Rysz from Member, TechnicalStaff, to Manager, Production Engineering.

Missile and Surface RadarLee Upton, Jr. from Senior Member,Engineering Staff, to Unit Manager,Systems Engineering.

Perry Willis from Unit Manager, EngineeringSystems Projects, to Manager, TestDocumentation.

Stanley Stern from Unit Manager, SystemsEngineering, to Manager, C&D Projection.

Gordon Caldwell from Unit Manager,Systems Engineering, to Manager,Facilities.

Harry Irion from Senior Member, Engineer-ing Staff, to Unit Manager, SystemsEngineering.

Kent Ringo from Senior Member, Engineer-ing Staff, to Unit Manager, EngineeringSystems Projects.

Roy Sewell from Senior Member, Engineer-ing Staff, to Unit Manager, EngineeringSystems Projects.

82

Herman Siegel from Senior Member,Engineering Staff, to Unit Manager,Engineering Systems Projects.

Charles Smith from Principal Member,Engineering Staff, to Unit Manager,Systems Engineering.

John Scarrow from Senior Member,Engineering Systems Projects, to UnitManager, Engineering Systems Projects.

James Sprinkle from Senior Member,Engineering Systems Projects, to UnitManager, Engineering Systems Projects.

Robert Cower from Senior Member,Engineering Staff, to Unit Manager,Engineering Systems Projects.

Ralph D. Rippey from Senior Member,Engineering Staff, to Unit Manager, Designand Development Engineers.

George L.EngineeringEngineering

Maas from Senior Member,Staff, to Unit Manager,

Systems Projects.

Staff announcementsPresident andChief Executive OfficerEdgar H. Griffiths has announced that PaulPotashner, Group Vice President, will beresponsible for:

Banquet Foods CorporationCoronet Industries, Inc.Oriel Foods GroupRandom House, Inc.RCA Records Division

Distributor and SpecialProducts DivisionJulius Koppelman, Group Executive VicePresident, has appointed James J. Badarac-co Division Vice President and GeneralManager, Distributor and Special ProductsDivision.

CommercialCommunicationsSystems DivisionNeil Vander Dussen, Division Vice Presidentand General Manager, appointed Henry H.Klerx Manager, Business Planning, a newCCSD staff position.

Neil Vander Dussen appointed Arthur J.Barrett Division Vice President, Manufac-turing.

Mobile CommunicationsSystemsLee F. Crowley has been appointedManager, Engineering and TechnicalServices, a new position in the Mobile

Communications Systems organization,reporting to Joseph P. Ulasewicz, DivisionVice President and General Manager. Inaddition, George R. Kamerer was promotedto Manager, Engineering.

Solid State DivisionCarl R. Turner, Division Vice President,Solid State Power Devices, has announcedthe organization of Solid State PowerDevices as follows: Angelo D. Checki,Manager, Operations Planning andAdministration-Power; Ralph S. Hartz,Director, Power Engineering; John E.Mainzer, Director, Power ManufacturingOperations; Robert E. O'Brien, Manager,Technology Transfer Program; and DonaldWatson, Director, Product Marketing-Power.

Ralph S. Hartz, Director, Power Engineer-ing, announced the organization of PowerEngineering as follows: Donald E. Burke,Manager, Device Development Engineer-ing; Edward A. Czeck, Manager, TypeEngineering; Robert J. Satriano, Manager,Process Equipment and Package Engineer-ing; and Wallace D. Williams, Manager, TestDevelopment and Device EvaluationEngineering.

Wallace D. Williams, Manager, TestDevelopment and Device EvaluationEngineering announced the organization ofTest Development and Device EvaluationEngineering as follows: Keith E. Louf-borrow, Leader, Technical Staff-TestEquipment Engineering; and Wallace D.Williams, Acting Leader-Test and Evalua-tion Engineering.

Dale M. Baugher, Manager, PowerApplications-Power announced theorganization of Applications Engineering-Power as follows: Wilfred P. Bennett,Leader, Technical Staff-Automotive; JohnCadra, Administrator, Market Planning-Cornmercial Coordination; Leonard M. Gib-bons, Leader, Technical Staff-Industrial/Computer; Thomas C. McNulty,Leader, Technical Staff-Applicance, Audioand T.V.; and William H. Schilp, Leader,Technical Staff-Hi Rel, Communications,Telecom and R.F.

Thomas T. Lewis, Director, Electro-OpticsOperations, appointed Carl L. RintzManager, Electro-Optics Market Planning.

Richard L. Sanquini, Director, Bipolar ICOperations, announced the organization ofBipolar IC Operations as follows: HeshmatKhajezadeh, Manager, Engineering-Bipolar IC; Seymour Reich, Manager,Bipolar IC Marketing; and John A.Schramm, Manager, Manufacturing-Bipolar IC.

Norman C. Turner, Director, MOS Engineer-ing, announced the organization of MOSEngineering as follows: Henry S. Miiller,Manager, MOS Reliability Programs;Eugene M. Reiss, Manager, MOS Hi -Reliability Engineering; George J. Waas,

Manager, Engineering Support; andAlexander W. Young, Manager, MOS CircuitDesign.

Peter J. Jones, Director, ProductMarketing-MOS, announced the organiza-tion of Product Marketing, MOS as follows:Andrew J. Bosso, Manager, ProductMarketing-MOS Distributor; Michael V.D'Agostino, Manager, Product Marketing-MOS Major Programs; Jack Handen,Manager, Product Marketing-MOS Hi -Reliability Products; Peter J. Jones, ActingManager, Product Marketing-MOS OEM;and Henry L. Pujol, Manager, ApplicationsEngineering-MOS.

Robert 0. Winder, Director, MOS Systems,announced the organization of MOSSystems as follows: Donald R. Carley,Manager, Custom Systems Designs; EdwinM. Fulcher, Leader, Hardware; Julius Litus,Jr., Manager, Support Systems; Larry A.Solomon, Leader, Software; and Robert 0.Winder, Acting Manager, New Products.

David S. Jacobson, Manager, PhotomaskOperations, announced the organization ofPhotomask Operations as follows: RobertNeste!, Leader, Technical Staff-Photomask Tooling; Robert L. Rhodes,Manager, Photomask Engineering & QualityAssurance; and Evan P. Zlock, Manager,Photomask Production.

Henry L. Pujol, Manager, ApplicationsEngineering-MOS, announced theorganization of Applications Engineering-MOS as follows: Richard E. Funk, Leader-Product Performance Engineering; Al A.Key, Leader-Memories/Microprocessors;and Henry L. Pujol, Acting Leader-LogicTimekeeping.

GovernmentSystems DivisionDr. James Vollmer, Division Vice Presidentand General Manager, has appointed PaulE. Wright Division Vice President, Engineer-ing.

Paul E. Wright appointed Fred E. ShashouaDirector, Advanced TechnologyLaboratories.

Paul E. Wright appointed Dr. Sidney RossStaff Technical Advisor.

PRICE SystemsFrank R. Frieman, Director, has appointedW. Kenneth Witzgall Manager, TechnicalOperations, and Dr. Robert E. ParkManager, Advanced Development.

Automated SystemsDr. Harry J. Woll, Division Vice Presidentand General Manager, has appointedEmmett 0. Seaborn, Jr. Manager, Com-mand and Control Programs.

83

RCA Service CompanyJoseph F. Murray, Division Vice President,Government Services, has appointedRobert S. Maloney, Jr. Division Vice Presi-dent of Navy Services and Artemus W. Wren,Jr. Division Vice President of Air Force/Ar-my Services.

RCA GlobalCommunications, Inc.Eugene F. Murphy, President, announcedthe organization of RCA Global Com-munications, Inc. as follows: Robert J.Angliss, Executive Vice President, SwitchedServices; Leonard W. Tuft, Vice President,Leased Facilities; Donald R. Stackhouse,Vice President, Operations and Engineer-ing; Thomas J. Brady, Vice President, RCAGlobcom Systems, Inc.; James C. Hepburn,Vice President and Technical Director;Robert Luongo, Vice President, Finance;Francis J.H. DeRosa, Vice President andGeneral Counsel, Law & Regulatory Affairs;Robert C. McHenry, Vice President, In-dustrial Relations; and George A. Shawy,Vice President, Corporate Affairs.

Donald R. Stackhouse, Vice President,Operations & Engineering, announced theorganization of Operations and Engineeringas follows: Eugene M. Gaetano, Vice Presi-dent, Pacific Operations; Notis M. Kotsolios,Director, New York/Kingsbridge Opera-tions; George M. Weisberg, Director,Operations Services Planning & Control;Robert T. Lundquist, Manager, AtlanticOperations; Alexander A. Avanessians, StaffEngineer; Louis P. Correard, Manager,Standards & Documentation; James R. Mc-Donald, Manager, Systems Engineering;Solomon J. Nahum, Manager, ConstructionEngineering; John P. Shields, Manager,Project Engineering; Roy B. Andersen,Manager, Administration & Planning; andJohn P. Feeley, General Manager,Philippines.

Consumer ElectronicsDr. Jay J. Brandinger, Division Vice Presi-dent, Engineering, appointed Dr. J. PeterBingham Chief Engineer, New ProductsLaboratory.

Dr. D. Joseph Donahue, Division Vice Presi-dent, Operations, appointed Charles A.Quinn Division Vice President, Materials.

Patent OperationsW. Brinton Yorks has joined RCA PatentOperations at the David Sarnoff ResearchCenter in Princeton, N.J.

RCA LaboratoriesJoseph H. Scott, Jr. Director, IntegratedCircuit Technology, appointed Dr. David E.O'Connor Head of the Solid State DeviceTechnology Group.

Letters

Our thanks to all of you who wrote tocomment on our last issue. We don'tnormally publish letters, but we did askreaders to respond to the anti -technologyattitude reported by Harry Kleinberg in hisarticle "Zen, existentialism, and engineer-ing." Part of those responses are givenbelow.

...I found H. Kleinberg's article in theAug/Sep 1977 RCA Engineer very in-teresting. This article gives engineers creditfor being people with interests outside ofEngineering.

I believe that an anti -technology attitudedoes exist but that it is much more prevalentin the non -technical world. People withouttechnical backgrounds or no interest inthings technical do not understand why orhow our mechanical and electronic marvelswork. They find themselves in an uncomfor-table position of having to depend uponthings that they have no hope of un-derstanding. When something goes wrong,they must depend upon others to makethem work again. This feeling ofhelplessness, I feel, gives rise to a negativeattitude about the technology that benefitsall of us so greatly. Technical people, on theother hand, feel more comfortable in thissame environment.

F.E. KorzekwaConsumer Electronics

...I am pleased that the article broughtPirsig's brilliant "Zen and the Art of Motor-cycle Maintenance" to the attention ofEngineer readers. I found it one of the moreexciting books of recent years. Florman'sbook I haven't read, but will look it up.

I have long been interested in philosophicalmatters, and concur that Pirsig's treatmentof the classical and romantic themes is welldone.

There are correspondences in the spectrumof scientist/engineer and artist/craftsman.In each, there are intuitive leaps to newdiscoveries that are not logical extensionsof given knowledge. There is skill to expressa discovery in a product. There arelimitations of media and time and money towork within. There are local customs to slowinnovation (we must conform to our stan-dards, artistic or engineering!).

Codification of discovery into standardpractice is necessary to teach others. Whatis lost, tragically so, is fun and absorption ofthe act of creation where a person is mostalive. Technical papers are usually devoid of

the excitement and textbooks are worse,giving the student the cut-and-dried resultsonly.

A survey of science given to a liberal artsstudent is as dead as a history of art or musicappreciation course to an engineer. Unfor-tunately, those who give these courses arenot creative workers in either field.

When the "public"' is given desiccated"science" in school and lifeless "art" via atechnical medium, and has no way toparticipate, there will be misunderstanding.

There are indications that the schism ofClassical and Romantic, Art and Science, ishealing. People who grow up with com-puters as toys will not be awed by them, anymore than by automobiles. Mechanisticscience has driven itself into the realizationthat the observer cannot separate himselffrom the observed. Large scale technologyfaces the stubborn fact that earth is a closedsystem. Artists are beginning to use televi-sion technology as a new medium of expres-sion. Pierre Boulez founded a newlaboratory for electronic music in Paris.

We are, perhaps, in a classical situationwhere extreme polarization precedes a newsynthesis.

The path of progress is not backward butforward to a new level of sophisticatedtechnology that will be more expressive tohuman creative impulses.

Thank you again for a most stimulatingarticle.

R.M. CarrellLaboratories

...I read the article on Zen and engineeringand was surprised to find out about theattitudes expressed. I retired about twoyears ago from a job I enjoyed very much.But retirement is even better. In general, myrelationships with other people in the com-munity were wonderful. I should say com-munities because I lived in four locationsfrom Maine to Florida in the last 6 years. Ineach, we have encountered a "caring andsharing" group of people that have made lifehappy. It may be that we expect to have niceneighbors and friends and therefore do havethem. No, the fact that I am or was anengineer never seemed to be a detriment inpeople to people relationships.

Eugene A. Mechlerex-MSR

Address correspondence to Editor, RCAEngineer, Bldg. 204-2, Cherry Hill, N.J.08101.

84

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NBC

BILL HOWARD` New York, N.Y. Ext. 4385

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644aicoa Engineer

A technical journal published by Corporate Technical Communications"by and for the RCA Engineer"

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