voyager&pager what do they have in common

8/14/2019 Voyager&Pager What Do They Have in Common

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Is There Any Relationship between Space&

Commercial Technologies

Voyager & Pager

What Do They Have In common

By: Mars [email protected]



?What Is the Similarity Between these 2 Systems



Perhaps The Only Similarity Is That Both Are NowRetired & Out Of service



But Before Any Judgment Lets Get

More Acquainted with Both Technologies



Voyager Mission Design



In 1965 Gary Flandro of the JPL Proposed a Plan in which, with taking the advantage of a once-every-175-year planetary alignment,lunching the fastest spacecraft ever towards the

GAS Giants was conceived possible.In his plan choosing a gravity assist trajectory,in which the spacecraft exploited a planet'sgravitational field to incr ease its velocity andalter its tr ajectory, thereby reducing both launchpower requirements and flight time , wassuggested. Later on the plan was called Grand

Tour.

The Backgrounds Of The Grand Tour



Shrinking the NASA andfederal Budget cuts, Scaled

back the Grand Tour in tothe Voyager Program .

The Voyager Program



The Voyager program consists of a pair of

unmanned scientific probes, Voyager 1 and Voyager 2 . They wer e launched in 1977 totake advantage of a favorable planetaryalignment of the late 1970s. Although they

were officially designated to study just Jupiter and Saturn, however with Gr and Tour in mindtheir launches were timed to enable the GrandTour if desired . Because of this alignment,Voyager could visit each of the Gas Giants in

just twelve years, instead of the 30 that would usually be required.

The Voyager Program



Voyager 1 is the farthest human-made object fromEarth, traveling away from both the Earth and theSun at a relatively faster speed than any other probe. Though its sister-craft, Voyager 2 , was

launched one month earlier, Voyager 2 will never pass Voyager 1. Neither will the New Horizons

mission to Pluto, despite being launched fromEarth at a faster speed than both Voyager craft,

since during its flight Voyager 1 benefited from anumber of gravity assisted speed boosts.

The Voyager Program



Voyager 1 was launched on

September 5, 1977 byNASA from CapeCanaveral aboard a TitanIIIE Centaur rocket, shortly

after its sister craft,Voyager 2 on August 20,1977. Despite beinglaunched after Voyager 2 ,

Voyager 1 was sent on afaster trajectory so itreached Jupiter and Saturnbefore its sister craft.

The Voyager Program – Voyager 1



Voyager 1s closest approach to Jupiter was on March 5, 1979. After completing the

mission using a gravity assist maneuver its course was changed towards Saturn.

Voyager 1' s Saturn flyby occurred in November 1980. Because of the earlier discovery of athick atmosphere on Titan, the Voyager controllers at the Jet Propulsion Laboratory electedfor Voyager 1 to make a close approach of Titan and terminate it’s Grand Tour. The Titan-approach trajectory caused an additional gravity assist that took Voyager 1 out of the planeof the ecliptic, thus ending it’s planetary science mission.

The Voyager Program – Voyager 1Trajectory & planetary science mission



Trajectory & planetary science mission

Voyager 2’ s closest approach to Jupiter andSaturn occurred on July 9, 1979 and August26, 1981 respectively. After the Saturn flyby,the camera platform on Voyager 2 lockedup briefly, putting plans to officially extend

the mission to Uranus and Neptune ineopardy. Fortunately, the mission team wasable to fix the problem caused by overusethat temporarily depleted its lubricant andthe probe was given the go-ahead to

examine Uranus.It's closest approach to Uranus andNeptune occurred on January 24, 1986, andon August 25, 1989 respectively .

The Voyager Program – Voyager 2

Dr. Ed Stone, project scientistfor the Voyager mission

JPL's director 1991-2007



The very long list of discoveries & achievements of theVoyager Program is beyond the scope of this presentation

however briefly:The two Voyagers have explored •more planets (four)•more moons (22), than any other space flight

•have returned 80,000 high-resolution images, •have returned 5000Gbits of scientific data •At more than 14 light-hours, Voyager1 is the most distanthuman-made object from Earth•Voyager1 is the first human-made object that entered the

heliosheath, the termination shock region between the solar system and interstellar space, a vast area where the Sun'sinfluence gives way to the other bodies in the galaxy

The Voyager Program - Discoveries



Scientific Instruments Onboard Voyager



instruments to support eleven scientific investigations

• Medium& high resolution television

cameras• spectrometers

• Photometric instruments for

atmospheric and other analyses

• radio receivers to measure planetary

radio emissions and plasma waves

• numerous sensors to measure fields

and charge particles

• high precision Earth/spacecraft radio

link for communication, navigation,

and science purposes



No deep space missions would be possible without a

reliable telecommunication system and Voyager wasnot an exclusion . The Voyager telecommunicationsystem consists of two parts, the system onboardspacecraft and the systems on Earth. At the launchtime Significant parts of the ground-systemtechnology in use for the Uranus and Neptuneencounters were simply unavailable however, it had adecade and a half to continue to develop to meet theneeds associated with steadily decreasing received

signal strength and also to improve navigationtechniques in the face of the increasing round-triplight time to the spacecraft .

The role of telecommunication in voyager mission



The ground-system

DSN 70-m Antenna goldstone



In different occasions different Earth Station

facilities were contributing to the mission.

•The NASA Deep Space Network (DSN)•Very Large Array (VLA), San Agustin, Socorro,

New Mexico•Institute of Space and Astronautical Sciences (ISAS),Usuda, Japan



The NASA Deep Space Network - or DSN - is an internationalnetwork of antennas that supports interplanetary spacecraftmissions. The DSN currently consists of three deep-spacecommunications facilities placed approximately 120 degrees apartaround the world: at Goldstone, in California's Mojave Desert; near

Madrid, Spain; and near Canberra, Australia. This strategicplacement permits constant observation of spacecraft as the Earthrotates, and helps to make the DSN the largest and most sensitivescientific telecommunications system in the world.

DSN



NASA Deep Space Network

Three 64-m DSN antennasX-band (8.5 GHz) receiving systemnoise temperature:20.9°K at 90 degrees elevation

25.5° K at 30 degrees elevation(in clear dry weather)

Main 70-m Antenna, DSN



Very Large Array (VLA) in New Mexico

27 X 25m antennas in a Y-shapedconfiguration equivalent to a single130 m diameter antenna



Officially the voyager 2 mission was supposed to be terminatedafter Jupiter encounter however the outstanding system design

including the computer control which in many occasionsguaranteed the system recovery from a wide range of malfunctions, encouraged the mission control to assign the newmission:

Exploring the Uranus and the Neptune



Mission Impossible

Exploring the Uranus and the Neptune



The effect of the distance on the space mission is very clear:The more the distance of the space probe the less the strengthof the received signal in the earth station, more over withUranus as the subject of the photographic imaging the problemwas not only the 6dB degradation of the signal (the power of the

received signal would be weaker by a quarter) but also it’s blackrings that is darker than the coal and the weaker the sunlight incomparison to the sunlight at the Saturn makes the situationtougher than one may think.The above condition would be severer when encountering

Neptune.

The role of telecommunication in voyager mission



The Solution

A glance @ the Miracle of Digital Communication



Noise

I n f o

r m a t i o

n

P o w e r Shannon

Theory



In his paper he showed that in the presence of theNoise (or what he called noisy channel), to transmit a givenamount of information there is a trade off betweenchannel bandwidth and the signal power (i.e.If the bandwidth is minimum to overcome the noise,

the signal level should be increased or if there is nolimitation on bandwidth the signal power could be kept low)He also showed that in a band limited communicationsystem by using an appropriate mathematical algorithm

(or what he called coding) there is a minimum power levelthat can satisfy the error free communication.

Channel Coding



In his paper he also showed that by removing theredundancy in the information it is possible to make

the message smaller. This way a loss-less method of compressing the data at the source is possible (sourcecoding) .

Source Coding



Matured & well defined

Yet Dead



At that time the theory was not understood,however, gradually the mathematical base of

theory was developed by other engineers andmathematicians. Days in days off a new codingalgorithm was introduced. At last the mostpowerful coding scheme the Convolutional codes

which is the base of today’s most popular codeswas invented, however, the complexity of thedecoding procedure was still prohibitive. In 1957this problem was solved effectively, a Sequential

decoding scheme that was really a breakthroughwas invented.



In 1959 the field which then was known as ”InformationTheory” or “Coding Theory” was matured and well definedhowever because of the prohibitive price of the neededcomputational power, and the complexity of error-correcting

schemes (decoder), implementation was not possible,hardware technology was far behind, that was why in 1960’sCoding was declared dead.



You Are My Destiny

You Are My Love



Once an Information scientist Called Deep

Space Communication and Coding a

“Marriage Made in Heaven”

Now Lets see why ?



•Power is Very Expensive in Space

•The Communication Channel in space is a prefectmatch of the noisy channel

•Bandwidth is plentiful in space, so in the trade off between free bandwidth and expensive power

the winner is the bandwidth

•The Expenses of a the computational power in aspace mission comparing to the overall Expenses

of the mission is pea nuts, in other words in 1960’sfor each 1dB of reduction in the power due to theapplication of the Coding Scheme 1000,000 $ Could

have been saved



The Decade Of

the Coincidences



Voyager Mission Design Coincided the:

once-every-175-year planetary alignment

Shannon’s Coding Theory

Introducing the Integrated Circuits

The Voyager Program



A Picture Is Worth

Thanone thousand

Word

The Impact of Coding



The Impact of CodingEvolution on theSpace Missions

Mars, Mariner IV, 1964using no coding

Saturn, Voyager, 1981

using Golay coding

Neptune , Voyager, 1989using Reed-Solomon

Mars, Mariner VI, 1969using Reed-Muller coding



The Coding Performance could be seen not onlyin the sample amazing pictures in the Previous Slide butalso in many others which are chosen as the background

of the entire Presentation. Specially please note the darker than the coal Neptune’s rings. The coding performancecould be judged by the very fine contrast between the ringsand the background. The dark rings could be distinguished

very easily from the dark background of the space.Voyager has used 2 encoding schemes in it’s entiremission. Lets hear the story and find out how it waspossible. It is an other amazing aspect of this interestingmission.

A mission which was first in many aspects



A closer look into the role of telecommunications in the

Voyager Mission



For the first phase of the mission, encountering the Jupiter and the Saturn, because Voyager was enabled for transmitting color images the information comparing to the

earlier mission was growing by three times so, GolayCoding scheme was chosen. Golay coding comparing to

previous chosen coding schemes was:

•Stronger in terms of error correction

•Faster in terms of channel capacity

For the rest of the mission, encountering the Uranus andthe Neptune and with the steadily weakening the received

signal some modifications should have been applied totelecommunication system onboard the spacecraft and tothe Ground system as well.



Encountering the Uranus

How 6dB Decrease of the received SignalLevel Was Compensated?



Remote Configurable Structures

Over-The-Air Programming

Redesigning the spacecraft and its instrumentdata systems in flight via uplinked software



4 dB Compensation

Applying a new Channel Coding and

a new Source Coding Scheme



In April 1985, with a hardware encoder included in theSpacecraft, an 8-bit (255,223) Reed-Solomon code with“interleaving depth 4” was applied to the X-band link, as anouter code . The inner code remained the 7, 1/2convolutional code. The Reed-Solomon encoder was

originally included on the spacecraft for compatibility withimage compression, which needs low error probability butefficient power use. The encoder was available at launch,but the corresponding ground decoder was available only

later, in time for the 1986 Uranus encounter.

Applying a new Channel Coding Scheme



The low error probability provided by the concatenatedReed-Solomon/convolutional coding enabled the use of alossless image-compression algorithm (a compressionfactor of 2.5) which was not available at the beginning of the mission. The spacecraft’s backup prime flight data

computer was assigned to carry out the data compressionalgorithm via software which was uplinked to thespacecraft.This was a very important contribution to the high imaging

rates achieved at Neptune. The algorithm was essentially auniversal source code on the differences betweensuccessive pixels on a scan line.

Applying a new Source Coding Scheme



2 dB Compensation

Real Time Arraying of Remote AntennasThe CSIRO Parkes Observatory, 64-m Antenna



Real Time Arraying of Remote Antennas

The additional 2dBimprovement of thereceiving signal wasattained by real timearraying of a 64-m radiotelescope antennaoperated by CSIRO atParkes with its 320-Kmdistant pairs(2X34-m +

1X64-m) in DSN facility atCanberra, Australia viaground microwave link. Canberra Deep Space Communication Complex



Encountering the Neptune

A New Challenge

A Further 3.5-dB Drop In Signal

Strength



Solutions to this new problem were foundin several modifications:

•The 64-m DSN antennas were upgraded to 70-mones

•All of the 27 antennas at VLA was equipped with Xband receivers and newly invented HEMT amplifiers

•Real-time arraying of 27 X 25-m antennas of VLA

with the 70 m and 34 m antennas at the GoldstoneComplex at the distance of 1920 Km via satellite. Thearray was equivalent to a fully steerable151-m aperture .



some times

I feel like a motherlesschild

a long way from home

Voyager Beyond The Solar SystemFrontiers

B h V 1 d V 2



Both Voyager 1 and Voyager 2 arestill functioning. Periodic contacthas been maintained with both

probes to monitor conditions in theouter expanses of the solar system. The crafts' radioactivepower sources are still producingelectrical energy, fuelling hopes of locating the solar system'sheliopause. It is now believed thatVoyager 1 has crossed thetermination shock in December 2004, with the heliopause an

unknown distance ahead.

Vo ager 2 is at a distance of aro nd 89 76 AU



Voyager 2 is at a distance of around 89.76 AU(approximately 13.42 terameters or 12.43 lighthours) from the Sun, deep in the scattered disc,

and traveling outward at roughly 3.28 AUs a year. Itis more than twice the distance from the Sun as

Pluto.



•As of the present date, the Voyager 2 and Voyager 1 scanplatforms including all of the platform instruments, hasbeen powered down.

•Only the Ultra Violet Spectrometer (UVS) of Voyager 1 is

still functioning.•The UVS data is transmitted at 160 bits/s via X bandtransmitter.

•Gyro operations will end in 2010 for Voyager 2 and 2011for Voyager 1. Gyro operations are used to rotate the probe360 degrees six times a year to measure the magnetic fieldof the spacecraft, which is then subtracted from themagnetometer science data.

Powering down



The two Voyager spacecraft continue to operate,with some loss in subsystem redundancy, butretain the capability of returning scientific data.Both spacecraft also have adequate electrical

power and attitude control propellant to continueoperating until around 2020, when the availableelectrical power will no longer support scienceinstrument operation. At this time, science data

return and spacecraft operations will cease.

Powering down

R f



.I) AFTAB, CHEUNG, KIM, THAKKAR, YEDDANAPUDI, “INFORMATIONTHEORY & THE DIGITAL REVOLUTION”,6.933 Project History,

Massachusetts Institute of Technology , p.p. 17-18

II) Edward C. Posner, Lawrence L. Rauch ,Boyd D. Madsen , “ Voyager Mission Telecommunication Firsts “, IEEE Communications Magazine, P.P.22-27 , Sept 1990

III) http://voyager.jpl.nasa.gov/mission/didyouknow.html

References



PAGER



Pager, mostly, is a single channel packet radio receiver which has a unique built in address (Cap Code) and is

used in radio paging or messaging networks.

Pager as a simple and cost effective communication tool,enables the user to receive, tone, tone & voice, callingparty phone number or textual message, based on the user

needs or preferences.

A l @ th hi t f P



A glance @ the history of Pager

Invented as nurse calling system by Alfred J. Gross in1949, pager was not welcomed by medical staff membersat first

The early pagers were analog tone and

tone & voice pagers and the target market washospitals and factories with a small coveragearea, usually in-building coverage

The first commercial use was licensed by FCC in 1952

Entering big companies, like Motorola, to the pager business gave the pager a new lease of life



The main problem of the analog pagers was: •The limited code capacity

The pager’s Cap code was dependent on the combinationof 2 tones out of 30 different tones (total capacity 870Cap code) (a metro extended version with 5000 Cap codewas available later)

•The false Cap code decoding thus false alerting

•The voice message was an other limiting factor thatlimited the paging service to an on-site private service

Paging as public Telecommunication Service



A B i f L k I M bil R di C i i



A Brief Look Into Mobile Radio CommunicationEnvironment and Wave Propagation

Unlike Deep Space Communication which is simplya Gaussian noise channel the mobile radiocommunication environment modeled by Rayleigh-fadingis much more chaotic & complicated and decreasespager sensitivity thus causes false alerting.



A Step Towards Digitalization

an evolutional approach

The First step

Addressing Digitalization



In 1977 Motorola finds the solution inCoding Theory

A variant of Golay Code which was selected as the

source coding in Voyager Mission and was used for sending error free images from Saturn and Jupiter wasconsidered as a potential nominee

That’s why once, one said the history of Pager is part of the history of Motorola



A Space Proof Technology



By choosing Golay code :

•Larger Code Capacity•More Fade Protection•More Sensitivity and Reliability•More Addressing per Second•Smaller False Alarming Probabilitywas attained.

Although the low-cost digital integrated circuits was not availableyet, Motorola paved the way towards a fully digital pager



In 1980, Motorola introduced the

first full digital Numeric capablepager.The address coding was based on

Golay (23,12) which could correct 3errors per Codeword and the messagecoding was based on BCH(15,7) which

could correct 2 errors per codeword.



The excellent performance of thepager in the metropolitan arearaised the public demand, however there

was a serious fear:

Pager was likely to be sacrificed by

it’s own success



A Highly Competitive Environment

The matter of death or life



The pager boom brought about some other important andcrucial issues. Manufacturers were concerned aboutIssues like:

•Time to market•The necessity of reducing production cycle•Demand for variety & for stylus models

•The Last but not least , Innovation, Innovation, Innovation

The matter of death or life



The Secrets of Survival

The Wave of Change



In 1979 the top management of Motorola realized that,with their high-quality products, Japanese pager makerswill winthe competition. The Motorola chairman RobertW. Galvin launched a company

wide drive to:•Accelerate new product development

•Drastically improve product quality

•Reduce the production line defects by tenfold before1986. This aim led to the invention of “6 sigma qualityprogram” in 1986, which means reducing defects to 3.4per million parts.

The Wave of Change



Creating a Knowledge Based Corporation

Galvin, also

• Initiated a top-to-bottom employee education and

retraining•Developed one of the best and largest corporate-trainingin the United States

To show the corporation’s commitment to training, a top-echelon policy committee mandated a minimumbudgeting of 1.5% of payroll for training

The inescapable necessity of change



The conventional production philosophy then, was based onoffshore production, however it had some hidden &

unexpected costs, like

•The separation of the design engineering function frommanufacturing function

•The execution of engineering changes

•Building to customer order

•Keeping quality and reliability at an accepted level

To find a solution Motorola executives began an extensiveprogram of visiting manufacturing operations around the world insearch for techniques which could be adapted for company’sown use.

The inescapable necessity of change



Project BanditComputer Integrated Manufacturing (CIM)

In 1985, the solution was found in Computer Integrated Manufacturing (CIM) and pagingproducts group was selected to verify thevalues of automated process in comparison

to intrinsic difficulties and intangible costs of off-shore Production and then to adapt theknowledge to other manufacturing operations . The team'swillingness to "steal" good ideas wherever

found, was the reason why they called thenew pager production facility in BoyntonBeach Florida, the Bandit Operation or theBandit Factory.



Project BanditComputer Integrated Manufacturing (CIM)

Promising Results



The CIM production line was prepared to design,develop, and produce Bravo pager within 18 monthsrather than 3 to 5 years for traditional Bravo.

The CIM system supporting the data base driven factory

allowed over 21 million combinations of product to bemanufactured individually, one at a time and to beshipped to the customer in a matter of hours comparedto days using traditional method.

The bandit factory proved that the idea of CIM was costeffective.

Accelerating new product development

Bravo, the world'sbest-selling pager

Produced in 1986

h R lt f B dit' CIM i l t ti



he Results of Bandit's CIM implementationby 1988

Inventory reduction 68%Cycle time reduction 99%Failure rate reduction 50%

Factory cost reduction 29%Parts reduction 25%Defect reduction 67%



Malcolm Baldrige National QualityAward

In 1988 Motorola (Bandit Factory)received the first National QualityAward which earlier was established bythe congress.



A Customized, High Quality, OnlineProduction Line

Inventing 6 Sigma Quality Program



Fusion, A New attitude to manufacturing

To attain 6 sigma, Motorola proposed a new manufacturingpolicy, “The Fusion”, through:

•Enhancing the environment for developing new products,not just for manufacturing them faster.

•Agile manufacturing system, enabling physically differentproducts to be assembled on the same line with no toolingchangeover.

•Intertwining development, engineering, and manufacturingIt allows engineers to create (not just manufacture) futurenew products right on line.



Paradigm Shift

From “Economy of Scale”

To

“lot size of one”




•Dynamically configurable workflow paths, enabling theorders of the dealers to be translated directly to uniquebill of materials and manufacturing process, even for asingle pager

•Technical Innovations,In the agile world-class manufacturing, new designs thatare created in the engineering lab, are transmitted to the

factory floor, and produced without a prototype.



Flexible assembly line, enables the Fusion Factory to buildvirtually any portable electronic product from calculatorsto personal digital communicators -as long as the designis represented on the computer system and parts are available

to the assembly robots. Many of Fusion’s concepts have beenapplied to Motorola factories worldwide.




A Programmed Approach

Towards 6 Sigma

6 Sigma

http://www.mpcps.com/index.html



Despite receiving the quality awardMotorola continued it’s struggle toattain to Zero- Defect Manufacturingthrough 6 Sigma Quality Program.

6 Sigma

The Aims of





The 6 Sigma quality program not only aims

•Zero-Defect Manufacturing (3.4 defects per million part)

but also quality in :

•Decision Making•Clerical Work•Shipping, and•Customer Service

The Aims of 6 Sigma

An Organizational Support




An Organizational Supportfor 6 Sigma Quality Program

•The Educational support is provided byEducation Center

•Bonus incentive performance reviewing•Intention to diffuse the program through it’ssupplier network

•6 sigma was a continuously improving campaignsupporting with a $100 million yearly educationand training effort in addition to management’stotal commitment.

A hi i 6 Si



•In 1993 the first product with the quality of 6 Sigma wasproduced

•By 1989, only 3 days were required from receipt of an

order to shipping for two-way radios, it was a substantialimprovement to the 18 months required a year and a half earlier.

Achieving 6 Sigma

References



I) SELECTIVE SIGNALLING FOR PORTABLE APPLICATIONSLeonard E. Nelson Motorola, Inc.Ft. Lauderdale, FloridaProceedings of The 28th IEEE Vehicular Technology Conference 1978

II) OPERATION BANDIT, CIM FROM A USER PERSPECTIVERussell A. Strobel, P.E., Motorola, Inc., Paging Division, Boynton Beach,

FloridaIII) Pocket pagers in lots of oneRuss Strobel and Andy Johnson, Motorola Inc.IEEE SPECTRUM SEPTEMBER 1993

IV) Improving Organizational Effectiveness Through TransformationalLeadershipEdited By Bernard M. Bass & Bruce J. AvolioCenter For Leadership Studies, State University Of New York, Binghamton



The Last Word

The Similarities



•Both Voyager & Pager are products of “Knowledge based Organizations”

•Voyager was the “Test Bed” for proving the performanceof “Coding and Noisy Channel Theory”, the base of digitalCommunication

•Scientists learned Many lessons from “antenna arraying” through Voyager encounters with Uranus and Neptune

•Pager was a test bed to understand the “mobile radiocommunication Environment” and “wave propagation

Models”•Recalling that the decoder is the much more complex partof a digital communication system, pager was the first pocketsized “Digital Decoder”

Vital role of error correction code



•The telemetry system of voyager is a one way communicationsystem, hence a kind of forward error correction was used, because ata distance of 4 light hours, ARQ, Automatic Repeat Request (asking asignal retransmission to make corrections to the errors) has no sense& is not practical

•Pager as a receiver, as well as voyager has no ARQThis results in, other benefits, like Saving in energy & in weight

•Both Voyager and Pager could be Programmed “Over The Air”

Space Missions a Key Path



Space Missions a Key PathTo Commercialization

Space Technology The Catalyst



Space technology as a leading edge technology, is mainlydependent on basic sciences that rooted deeply in 19th & the first

half of 20th

centuries. As an example the Reed-Muller codingwhich was used in Mariner VI mission was based on “HadamardMatrices” found in 1893.

Basic SciencesMathematics & Physics

Space Technology

CommercialTechnologies

Space Technology as the catalyst for commercializingBasic Sciences to our daily life

From Heavens Down To The Earth



Simply, If the telemetry of Voyager mission, for any reason, wasnot dependent on coding theory, the evolution path of digital

communication was much slower than what we witnessed, anddefinitely even a cost effective, simple but efficient technology -Interms of frequency utilization- like paging was not available assoon as we experienced. Now a days we just simply use car anti-burglar small and power efficient encoder/decoders unconsciouslyand do not know what a long history of development, lies behind itand do not know the role of knowledge based progressiveorganizations, like Motorola, in the field.

From Heavens Down To The Earth



Thank You

By: Mars [email protected]

voyager&pager what do they have in common

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