the history of high com

17/9/2014 The History of High Com

http://www.ernstschroeder.de/highcom_d.htm#telcom 1/23

The history of HIGH COMErnst F. Schröder

First contentPrefaceThe beginnings in the basic developmentThe telcom companderThe beginning of the development of HIGH COMNakamichi comes toHIGH COM arisesHIGH COM IIHIGH COM PromotionHIGH COM in BeijingEven more companderClosingLiterature

Second preliminary remark

This is the story of the history of the HIGH COM (*) compander. It is closely linked withmy time as a development engineer in the Telefunken basic laboratory in Hannoverfrom 1970 to 1983 It is based on surviving records and photos as well as on thememory to the best of knowledge.My thanks go to the former colleague Jürgen Wermuth and Hans-Juergen Kluth, whocontributed facts, images and corrections. I would also like to thank Manfred Geskeand Ingo Weishaupt, who provided photographs of their HIGH COM devices.

3rd The beginnings in the basic development

My time at Telefunken began on May 15, 1970 Posted I was a development engineerin the basic development. This was a decorated specially for Professor Walter Bruchdevelopment department. She was not in the main building in Hanover Rickingen, butsince about 1968 at the other end of the city, 215th Street in the VahrenwalderProfessor Bruch himself know I had already learned during my studies, but in his lab Ihad become only carefully publication in the radio show [1] Werner Scholz, anemployee of the laboratory. There it was in fact a subtitle: "The author is an employeeof AEG-Telefunken, basic laboratory, Hannover".At the presentation in the Telefunken HR department wanted to me though necessarilyenthusiastic about the TV product development, let me then but a little disappointed butthe "exotic" pull in basic development. The time as a young engineer, I initially spent with all kinds of small projects andsupport for others. A regular, beloved but some also unpopular activity for all membersof the laboratory was the demonstration of the benefits of the PAL color televisionsystem. The unique technical equipment of the laboratory equipment in various colorTV standards NTSC, SECAM and PAL namely you could demonstrate the differentbehaviors of certain disorders and thus the benefits of PAL.Such demonstrations were more or less regular basis. Each lab member had it itsplace in certain devices, while Hans-Juergen Kluth was the master of ceremonies. He



listened to the lecture and gave the instructions on microphone: "PAL", "NTSC", "Saw","Rotierphase" and so on. A standard command to Günter Brandt, the operator of the35mm film scanner, was shortly after the start of the 35mm color film "pallets offashion": "more green" . Especially lasting memory I stayed in was before most

different audience from all these occasions the sovereign manner in the Professorbreak his lectures. In the yard was still the Magirus bus, who had served for the PAL demonstrations inSouth America in 1968 as a transfer cart. With its strong air conditioning, he was afavorite retreat on hot summer days, even if actually waited another job. Sometimeseven the ingredients for "Cuba Libre" stray in this bus. Here you can see me on thevideo mixer the transfer carriage together with Professor Bruch and my colleaguesGunter Raschke.

Figure 1: Professor Bruch, Gunter Raschke and the author in the PAL broadcast vans One of my first projects was the investigation of a novel electronic device, the bucketbrigade device in July 1972. A variable analog memory element for audio and videosignals could for example be realized variable delays. As an application example, Ichose the elimination of pitch variations in a simple recorder for Compact Cassette, aTelefunken stereo sound TD. As can be seen on the following Scope Displays, thiswas achieved quite well, the pitch fluctuations are significantly reduced. However, thismethod required in any way the additional recording a kind of pilot tone. That was notvery promising for a consumer device product, but overall it was a good example ofapplication of these new devices.



Figure 2: wow and flutter of a tape recorder . unchanged below, compensated above the horizontal axis 50 ms / part, vertical axis 0.33% / part In 1973 Professor traveled break in the USA and visited the former laboratory ofThomas Alva Edison in Menlo Park. From there he returned with a box of old Edisonsound cylinders. My job was to pull down the tone of these cylinders. To this end, wepresented in a simple Telefunken turntable the platter vertically, built a conical roller onthe turntable and turned the tone arm to 90 degrees. By swapping the connections onthe stereo-pickup then you could remove the signals of the Edison-depth writing on thesound cylinders as a mono signal and save on tape. Although the laboratory had manyvideo encoders, but hardly audio devices. Luckily I had some private devices, with theirhelp I was able to improve the subjective quality of the recordings. The most notable of these recordings is that of the bell of Big Ben in London, recordedon 16 July 1890 Recording droning a bit because it was made with a languageintended for actually recording device propelled by a spring motor. Another unique recording is the signal for the attack of trumpeter Lansey , one of thesurviving trumpeters of the Battle of Balaclava in the Crimean War, 1854 Just thissignal, so he says he has on the same horn on 25 October 1854 as a command forlossy attack the "Light Brigade "blown. Professor Bruch processed his extensive collection on the history of sound and imagestorage eventually a series of articles in the radio show [2] . To my other duties included keeping track of new developments in the field of televisionbroadcasting. Therefore, in November 1974, I traveled to the BBC in London and gotthere the very first version of CEEFAX to see. This is what we call teletext today. Thecolor digital representation of text on a television screen was new and very impressiveat the time.

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4th The telcom compander

The Faculty of wide area and wireless technology the AEG-Telefunken, there was adepartment that specifically dealt with professional electric acoustics and studiotechnology, the ELA in Wolfenbüttel in the Linden Street 15thThere sat with Jürgen Wermuth a young design engineer, which dealt among otherthings with low noise microphone amplifiers. AEG-Telefunken was then also partners ofDolby Labs in London for their used in professional tape recorders Dolby-Acompander. Jürgen Wermuth had something to do with this companders and was notsatisfied with their technology and the problems that occur repeatedly. So he satthereon to develop a much better compander in his spare time. That was just about atthe beginning of the 70s. He wanted to solve the following problems here:

Higher Kompandierungsgewinn

Freedom of accurate leveling

Independence of component fluctuations The solutions found Wermuth for the above development objectives were the following:

Compressors and expanders in field effect transistors (FET) have been usedas a variable resistance and adjusting elements are preferred. To operatethis distortion, they had to be operated appropriately balanced circuit. Inaddition there was a solution of Rolf Roeder at Sennheiser [3] , but had anadverse effect on fast control operations due to the use of RC elements.Wermuths solution [4] used only operational amplifier for balancing and wastherefore much better suited for compander.FETs as variable resistors showed large individual variations. Wermuth

developed to a circuit [5] , with the help of double-FETs (two identical FETson a piece of silicon) yielded variable resistors with very low manufacturingtolerance.By use of the distributed amplifier principle [6] it could produce a virtually

unlimited linear companding. In this circuit, a plurality of identical positionamplifier are connected in series with a variable gain amplifier and thevoltage at the end held constant. So automatically results at eachintermediate stage, a level linear compressor characteristic. Thecorresponding expander circuit is determined by slight modification of thearrangement of the amplifier chain. telcom c4 uses three control amplifier andthus a compression curve with a slope of 2.3.The distributed amplifier principle requires, at its end, a special circuit forgenerating a control value for the amplifier chain, which causes the voltage atthe output of the last amplifier chain is held constant. Used for this purposedeveloped by Wermuth circuit for charging and discharging of a capacitorthrough a constant current sources [7] .



Figure 3: Representation of the amplifier chain principle and the achievablecharacteristics After initial hesitation, the management of the ELA Wermuths development result hasfinally accepted and made a product thereof. The result was the Telefunken companderwith four separate frequency bands, thus eventually called "telcom c4". Presumably, Stephan F. Temmer, the founder of Gotham Audio Corporation, who wasalways looking for new and better solutions for problems of audio technology and theTelefunken products in the United States sales to this decision at the ELA helped. Ofcourse all this is not just led to a better relationship with the Dolby Labs. The first performances of new compander finally took place in the fall of 1975 at the10th Tonmeistertagung in Cologne [8] as well as in the radio show [9] .



Figure 4: View of one of the first telcom boards (photo Jürgen Wermuth)

5th The beginning of the development of HIGH COM

In addition to the work on a compander for professional use Jürgen Wermuth had alsodealt with a variant for use in application and recorders for compact cassettes. Hecalled them "RUSW", the "noise reduction system Wermuth". On April 23, 1974 Wermuth has finally be "RUSW-200", coupled with a Telefunken MC3300 cassette recorder, presented to members of the Management Board, productdevelopment and patent system.



Figure 5: View of RUSW-200 prototype (photo Jürgen Wermuth) On 09 July 1974 I quoted Dr. Klaus Welland, Chief Technology Officer at Telefunken, inhis car and drove me to Wolfenbüttel for ELA. A remarkable in several respects ride,he was known to me not only as a board and as a radio amateur (callsign DL1MR), butespecially as a rapid driver. Well, I survived it. In Wolfenbüttel there was a conversation at the highest level at which Jürgen Wermuthand I were allowed to participate. As a result, it was revealed that for the consumerversion of the new compander in the AEG-Telefunken Telefunken naturally Group wasresponsible in Hanover and that further development of this method from now on shouldbe taken from me. For this I received from Jürgen Wermuth beginning August 1974detailed written documents and even have a design for an analog integrated circuit.It is interesting in passing that during this meeting in Wolfenbüttel was revealed thatAEG-Telefunken was terminated the exclusive distributor for Dolby A units of Dolby. Professor Bruch had now passed the direct line of development laboratories in otherhands. Dr.-Ing. Gerhard Dickopp came with a part of his team from the Telefunkenlaboratory in Berlin to Hanover. There he had worked until the early 70s instrumental inthe development of Telefunken Teldec image plate TED. The color process "Tripal"used in the TED image plate was contributed in Hanover collapse of basicdevelopment. I too had contributed some ideas to the development ofTonaufzeichnungsverfahrens used in TED image plate. I set to work immediately. The originally proposed by Wermuth circuit contained thebasic ideas of telcom, but had the sake of simplicity only two connected in chain control



amplifier and used only two separate frequency bands. For further simplification, onlythe audio signals were companded in the higher frequency range. The transitionfrequency between the unkompandierten and the companded frequency range waspractically constant. A short time later, the first draft was redesigned so that a compander emerged with amuch lower sliding-band characteristic, which was also used in the presented Dolbyalready in October 1969 Dolby-B system. However, this system was just not theunderlying division into "main path" and "further path" [10] used. The total profit of thenew compander was about 20 dB, or about twice as high as in the Dolby-B. In June1975, the first patent application was [11] submitted to the new compander. Furtherpatent applications were then developed in rapid succession.

Figure 6: Schematic diagram of a sliding-band compressor with two distributed

amplifiers

Figure 7: The Sliding-band frequency responses of the compressor as shown in Figure

6 Early 1976, there was another notable event in the Telefunken basic researchlaboratories. On one occasion some of the engineers had sat together and fool arounda bit and it compiled crazy ideas to television technology. Since we were working withvideo recorders, the question arose as to how one can start video recording timeexactly when the show was once again against the information broadcast time delay in



the program guides. Benno Jahnel- that a colleague who had recently changed fromBerlin to Hanover, had the crucial idea and then submitted it as an invention disclosure:The station is not broadcasting on an additional digital channel as the current time, butan incorrect time information, namely the desired start time of the shipment. The ideaemerged from this patent [12] led to the still used VPS process in televisionbroadcasting and to no small royalties for Telefunken. In October 1976, I then one by Jürgen Wermuth and wrote me talk about theprofessional telcom c4 and the yet-unnamed compander for consumer application heldat the meeting of FKTG in Freiburg [13] . I remember very well that Elmar Stetter, therepresentatives present from Dolby Labs, was not very pleased with this newcompetition. For an actual application in consumer devices, it was necessary to realize thecompander as integrated analog block. So I went in the spring of 1977 on the AEG inUlm and AEG-Telefunken semiconductor plant in Heilbronn. There I met DietrichHoeppner and Kurt Hintz man. The latter was then that the original design by JürgenWermuth with the changes I have developed in an analog integrated circuit [14]followed it. When the first samples were available and also worked as desired, I received aninvitation from the Hessischer Rundfunk. End of September 1977 designed JoachimBublath there with me and my pattern device a program about audio compander.

6th Nakamichi comes to

Meanwhile, Stephan S. Temmer had turned back. He had heard good about hiscontacts with the AEG-Telefunken ELA in Wolfenbüttel assume that at Telefunken inHannover a consumer version would be developed by telcom. This message he hasapparently passed on to the manufacturer of the unchallenged at this time best taperecorder: the company Nakamichi in Tokyo.It was not long and the complete management of Nakamichi, led by company founderEtsuro Nakamichi, appeared at Telefunken in Hannover in the Vahrenwalder road andhad a demonstration of my new compander. They were very impressed, on the otherhand almost appalled, had to handle with what cruel poor equipment of poordevelopers. Instant freight shipment of the finest Nakamichi equipment was sent on their way: AN1000 and N600 cassette recorder, preamplifier and power amplifier, a special audiometer, the T-100 Audio Analyzer, and two huge speakers. In comparison with the thentypical hi-fi equipment from Telefunken was something special, which has alsoinfluenced the further development of the compander sustainable. In Nakamichi had originally planned to use the telcom c4 compander in the high-endcassette recorder and N1000 as to bring the ultimate recorder for Compact Cassetteon the market. But AEG-Telefunken ELA wanted telcom c4 seen only in professionalapplications and denied a license, not to point without the yes in developmentcompander for consumer devices. After they had experienced in the now function andeventually get two working prototypes in July 1977, agreed to and waited for the massproduction of ICs.A preliminary license was posted on June 24, 1977 then closed between Nakamichiand AEG-Telefunken.



7th HIGH COM arises

Although it was decided that new cassette recorder of Telefunken were not equippedwith Dolby B but with the new own compander. Meanwhile, the fear had in theTelefunken development line but probably common that you could be involved becauseof a certain similarity to Dolby-B in a lengthy and expensive patent litigation with Dolby,even if you were convinced that you're not the patents of Dolby Labs injured. I thereforewas commissioned to investigate other Kompandervarianten. However, the IC wasnow almost finished, so what could still change it? In at least until 1925 [15] returning History of companding audio signals companderwere originally only once been developed which all the sound-frequency band at onceprocessed, ie broadband compander. Most of them had been found less suitable, suchas the later developments of EMT [16] , Burwen [17] and dbX- [18] . At least since 1937, it was generally known [19] to divide the entire audio frequencyrange into several separate areas and to compand then separated. This interpretationas Mehrbandkompander had certainly also to the success of Dolby-A [20] contributedand has also been used in telcom c4. For a compander for consumer devices thatwould have meant an expensive multi-effort. But with the great principle of linearization amplifier chain, the special control signalgenerator and such high-end cassette recorders such as the Nakamichi 1000, whatcould happen? The components that generated the sliding-band effect were quicklyremoved. The problem of the lack of noise masking the simple Breitbandkompanderwas tackled with an additional pre / de-emphasis, and the dreaded occurrence ofnoise bursts behind abruptly ending useful signals was performed using a specialcontrol signal generator [21] and a signal-dependent between "slow" and "fast"switchable time constant solved.Both the static and the dynamic behavior of this Breitbandkompanders was extensivelytested with all types of music and in particular with the stop signal of a triangle. Thistriangle I still own.

Figure 8: stop signal of a triangle, reproduced from a tape recorder, unkompandiert up,down with HIGH COM There is only a very slight distortion at the beginning of the signal visible.



Figure 9: Photo of the triangle used On 11/28/1977 I have then both versions, sliding-band and broadband, presented withthe results achieved as well as their advantages and disadvantages of thedevelopment line of Telefunken.The development outcome was found to be good and the choice fell on theBreitbandkompander. This, however, had the integrated circuit are complementedwhat a complete redesign equaled. That was probably somewhat higher spatial troublebetween Telefunken in Hannover and the AEG-Telefunken semiconductor plant inHeilbronn. In February 1978, appeared in the Broadcasting Service Bulletins (RTM) an article [22]by Dr. Dickopp and me, who described the new "Telefunken compander", bothprofessional telcom c4 and two variants of the consumer compander, both the versionwith sliding-band as well as the newer broadband version. A further development occurred in the spring of 1978: The Düsseldorf exhibitioncompany probably wanted to take away the Berlin exhibition company something of thebusiness of consumer electronics and had therefore planned a rival event to the BerlinRadio Exhibition. The end of August 1978 was to take place the first Hi-Fi Show inDusseldorf. But the Germans Hi-Fi manufacturer spared the additional costs that theywere already engaged in taking place every two years IFA in Berlin. They thereforedeclined to participate. The emerging competition from the Far East but took joyfully. Telefunken now had the new compander and also just got a new high-quality cassetterecorder with Direct Drive ready. Therefore, it was decided at short notice and contraryto the original announcement, but now at the Hi-Fi Fair participate in Dusseldorf. Nowfollowed hectic preparations, because so far there have been few functionalcompander ICs that had to be prepared also with external devices for the broadbandversion. So I have set up some boards with the Breitbandkompander and Bernd Wieden Rothfrom the product development they married with the new recorder, the TC750.



Figure 10: Front view of a Telefunken TC750 It had now of course a name for her new compander. After some searching, theyagreed on the name "HIGH COM". The exact spelling of the way, contains a half spacebetween "HIGH" and "COM". That was something electric typewriters back then couldafford absolutely. But it was difficult to explain and can also represent today only withdifficulty. A logo was designed which contained an appeal to Magnettonköpfe:

Figure 11: HIGH COM logo on the cassette holder cover a HC1500 The effort, the Telefunken for this Hi-Fi sales fair was enormous. In the back of thestand absolutely soundproof screening room with air conditioning was set up with tonsof sand between double walls. In this report you the best devices on the Telefunken hadto offer, and of course the TC750 HIGH COM. The pre-recorded music for our demonstrations I got in Berlin from the Teldec. The thenchief sound engineer, Professor Martin Fouqué, provided us with copies of storedtelcom c4 originals available, we copied this with HIGH COM on chromium dioxidecompact cassettes. The achievable quality was really impressive. In the audience was the best in arecording of "Also Sprach Zarathustra" by Sir Georg Solti. Of course, a technical demonstration was part of the demonstration program. With thehelp of working in real time Terzanalysators Brüel & Kjaer (type 2131) could makeoptically visible and compare the gain in signal to noise ratio also.



Figure 12: Representation of the Kompanderwinns on a real-time third-octave analyzer,left: Dolby B, right: HIGH COM dark: noise spectrum without bright: with compander

From 18 to 24 August 1978 I conducted a total of 16 one-hour lectures anddemonstrations on HIGH COM alternating with Bernd Wieden Roth. In addition, as'sometimes just' two in English and two more for the press. On the edge of the opening press conference on August 17, 1978 it was announcedthat Dr. Dickopp, the then head of the Telefunken basic development, a call wasaccepted to the University of Duisburg. The Telefunken management decided after the successful appearance in Dusseldorfthat there must be a HIGH COM representative for further marketing. The contract wasawarded Dr. Thuy from Berlin. He came to Hanover and moved into the former office ofProfessor Bruch. Meanwhile, I had already but this space-empted and equipped foracoustic experiments. My device I had built up in front of the giant mural showing theyoung engineer Walter Bruch in 1936 as a cameraman in the Berlin Olympic Stadium.Another suitable room there was not in the building. Well, I have not let me sell and wehave arranged for us ... The end of September 1978, finally the long-awaited first working model of the HIGHCOM ICs, so the U401B, delivered from Heilbronn.Also in September, appeared in the radio show a paper by Dr. Dickopp and me inwhich we darlegten that a metrological evaluation of the stationary properties ofcompanders really should only be done with the help of noise signals and an octaveanalysis [23] .

8th HIGH COM II

Contacts with Nakamichi passed on, but there is still thought you finally get somethinglike a Dolby-B compander with sliding-band, but with significantly better properties.Telefunken had now but definitely opted for the broadband version. On 20 September 1978, therefore, was the vice president of Nakamichi, Mr. S. Takaito Hanover. The result was a large and typical misunderstanding. You heard of him



always "hai" and gave the illusion that Nakamichi was now satisfied with thebroadband version. The cleared only after his departure. Of course, Nakamichi did notagree. What to do? After some thought there was a way out that even something closer approached inwhat Nakamichi had originally intended:Using the developed for the Breitbandkompander HIGH COM IC U401B aMehrbandkompander was developed specifically for Nakamichi. At this time I worked in complete overload operation, because be built and tested withthe first 50 samples of the ICs had U401B pattern boards. Of course there was nospecific support for this, it was complete hand work of a single person. By the way hadto be defined and implemented for the semiconductor factory test procedures. Andthere was only one who really knew about HIGH COM ... Therefore received Werner Scholz, a longtime colleague from the basic laboratory(who was allowed to use and switch at the PAL demonstrations always the PAL, NTSCand SECAM decoder), a short briefing and mission, both two-band and a three-bandversion of HIGH COM build. He completed usual precision and invention [24] , and inApril 1979 there were working prototypes that met the expectations in principle.Nakamichi favored, probably for reasons of cost, the Zweibandkompander, but overallwas not quite satisfied with the function. Of course I had also tested the results andfinally added another crucial detail solution added, namely an additional pre / de-emphasis in the lower of the two frequency bands [25] . Then you need only the solutionfor another small problem: it had to go to Nakamichi someone. Well, you did not haveto look far. From 06th-13th So in May 1979 I visited the Nakamichi Labs in Tokyo. They had aspecially good English speaking native Japanese, a young engineer from LosAngeles, flown as a sparring partner. With Harron K. Appleman I sat every day until lateinto the night in the listening room and changed the parameter of the compander untilfinally the "golden ears" of Nakamichi were satisfied. I wanted off resistors andcapacitors and solder itself and that I could read color code, which was aroused by abit of attention. But in the end everyone was happy and HIGH COM II was born. NowNakamichi had to turn it into just a product, but this was professionally done in the usualway.

Figure 13: View of a Nakamichi HIGH COM II device (photo Manfred Geske)

9th HIGH COM Promotion

Even before the Hi-Fi show in Dusseldorf, but especially also by the subsequentactivities of Dr. Thuy, the representatives of many manufacturers of consumer devices



ranged jack in the hand and HIGH COM could be demonstrated. At least as often, I hadto travel to one of these manufacturers. In July 1979, began a collaboration with the Institute of Radio Technology (IRT) inMunich, which would extend over many years and left me some years to travel almostonce a week to Munich.From July 1979 we are now led discussions on the Kompandereinsatz in FM radio. Forthis purpose, the IRT some time had already previously made studies with the Dolby Bcompander [26] . Beginning of 1980 was finally the font information in the AEG-Telefunkensemiconductor plant in Heilbronn [27] for HIGH COM IC U401B finished. Text, picturesand drawings came in consistently from Hannover. Meanwhile, people spoke ofU401BR, while it has a total given three slightly different versions of this Ics:

U 401 BU 401 B with a yellow dot or U 401 BGU 401 BG with blue point or U 401 BR

On February 7, 1980 at 21:45 clock was in the West German Radio broadcastHobbythek by and starring Jean Pütz on the transmitter. In this show HIGH COM wastreated intensively and finally the Hobbythek version of an attachment with HIGH COMpresented: HobbyCom. The little device used the same modules, used the Telefunkenalso in all his cassette recorders. The application circuit around it had been designedin the Telefunken product development. As is usual in Hobbythek, the device could bepriced based as a kit.

Figure 14: View of a HobbyCom device (photo Ingo Weishaupt) From 04 to 18 May 1980 organized a Telefunken HIGH COM promotional tour inJapan. Participants were of the Chief Development Officer Dr. Klaus Welland and Rolfslide ring from the sales, as well as one who had to do the work. The reader may guesswho that was.In Tokyo Hilton Hotel, a presentation room was prepared and held demonstrations of



HIGH COM for representatives of 34 companies.

Figure 15: A HIGH COM presentation at the Tokyo Hilton From 19th-24th August 1980 was then in Dusseldorf second HiFi Fair. ThereTelefunken was awarded the German Hi-Fi award for the development of HIGH COM.At the ceremony, of course, only board members were present.It can no longer see where this price is ended up. But at least there is a photo of thetrophy.

Figure 16: German HiFi Award 1980 The inscription reads:THE COMPANY TELEFUNKEN AWARDED FOR THE DEVELOPMENT OF NOISESUPPRESSION SYSTEM HIGH COM FROM HIFI MAGAZINE sound

The local press took up the topic. On September 5, 1980 appeared in the Hannover



Allgemeine Zeitung half-page article entitled "Rushing river of sounds is cleaned in themilitary". In the first paragraph, the author tries in prophecy: . "That brick building Vahrenwalder Road 215 will be some day maybe awarded aplaque here, you will mean the audiovisual relied descendants, Revolutionary was inthe sixties and seventies, invented for the eyes and ears - Walter Bruch developed inthis home for the TV color system PAL and his young employee Ernst Schröder helpedthere later the tape cartridge from its infancy. " Now that Telefunken had moved in 1983, the building was demolished in the nineties.So it was no place for a memorial plaque. Finally, PAL was also not here, but has beendeveloped in a basement laboratory in Hanover Rickingen in the Göttingen Road. Towards the end of 1980 Telefunken finally was able to report that more than 25company license agreements were signed and that more than 35 companies can beconsidered HIGH COM system partners worldwide. But in 1980 was also the year in which Dolby Labs Dolby-C method was presented, asliding-band compander, who used two of the ICs used for Dolby-B, and thusgenerated a gain of about 20 dB.

10th HIGH COM in Beijing

At AEG-Telefunken had now been some drastic changes. After record losses in 1979was appointed Chief Executive Officer on February 1, 1980 Heinz Dürr.For the first two weeks of January in 1981 planned AEG-Telefunken a large industrialexhibition in Beijing. Telefunken was given the task to issue consumer electronics andespecially the PAL color televisions. At a same time held in Beijing Colloquim atechnical presentation on HIGH COM was announced.The preparations were extensive, and just before it was to start properly, the availablefunds were slashed. For Telefunken it remained at the exhibition devices and thereported speech. The booth staff was slashed to a minimum, so that only one personwas left: me. On December 28, we started with a Chinese Jumbo via Paris to Beijing. In Paris therewas a thick fog, the plane was diverted to Frankfurt. The night before the scheduleddeparture to Paris I received a call and was just in time a plane to Frankfurt and thusthe Jumbo reach to Beijing. A stopover there was in Qatar, one of the UAE. I had theimpression that the airport in Doha had been opened so deep in the night extra for thisone plane only. Today it seems there certainly completely different. Upon arrival in Beijing, we were housed in the Friendship Hotel, a building from theperiod just past the large Russian-Chinese friendship. In a similar style and theexhibition building was held. There was of course a Chinese restaurant, but also aninternational restaurant. The two differed in that it was in a knife and fork instead ofchopsticks. After all, both restaurants were well heated. The exhibition program was exhausting, the hall was hardly heated, but the generalmood was good. I was assigned to a team of four Chinese who spoke a little Germanand English and were very proud of it. The audience was enthusiastic about theexhibited consumption devices and the Telefunken catalogs were formally torn from my



hands. Finally I had to strictly ration the few remaining catalogs.

Figure 17: The whole team of AEG-Telefunken exhibition before the exhibition building Also remarkable for me was a certificate issued by AEG-Olympia typewriter, with theirink spray technology could bring Chinese characters on paper. However, the operatorwas ordered to a specific encoding of the typewriter keys have internalized if hewanted to produce certain Chinese characters. Here I also had my first encounter with a PC. As far as I can remember, that was aportable TRS-80 that a fair team of AEG for his presentation required. Of course, werethe very proud and demonstrated to colleagues, so that you could play games. My lecture on compander, especially on HIGH COM came in very good. I had to givefor about an hour answers to very specific questions afterwards. Apparently they hadvery carefully prepared. I remember well the dress code of the professors andscientists in attendance: Blue, ungebügelter work suit and glasses with broken glasses.The party officials were also easy to recognize, their suits were ironed.In March 1981, then appeared in the Chinese magazine "Audio Engineering", anarticle on HIGH COM, which was based on my paper [28] .



Figure 18: The exhibition team at the Telefunken booth

Figure 19: First page of the article on HIGH COM

Of course there was also a social program. We visited the relevant attractions, theForbidden City, the Summer Palace, the Ming Tombs and of course we also went tothe Great Wall in Badaling. It was still very cold so we did not come out there evenwhen eating in the restaurant from our thick coats.



The best memory of Beijing for me is still the one to walk across the frozen lake at theSummer Palace, in the bitter cold and deep standing and because of the smogyellowish red glowing sun.

Figure 20: The Great Wall at Badaling early 1981

11th even more compander

Beginning of 1981 were the problems at AEG-Telefunken and the daughter Telefunkentelevision and broadcasting GmbH in Hannover always tangible. Defined tasks and aVice President for Development was no longer there. I began my search to my workitself. The Grundig used in her video recorder Video2000 a built with discrete componentsAudio compander. After some discussion, the AEG-Telefunken semiconductor plant inHeilbronn was commissioned for it to develop an integrated circuit, which also coveringother functions. The contract for the development of Kompander I received. The projectwas successfully completed and my work was paid for by Grundig. Also presented in autumn 1981, the CBS in the United States compander for records



before, the CX-System [29] . Also for this I developed from January 1982 together withthe designers in the AEG-Telefunken semiconductor plant an integrated circuit. From 5to 9 April 1982, I drove to CBS in Connecticut to get tested there the finished circuit(U2141B). I was also good at the hotel, but was then held there for a day because asnowstorm had stopped all traffic and all public activities. The following day I met DanGraveraux, the head of the CX development teams at CBS. In a pleasant atmosphere,we tested the circuit and I received the longed OK. This time my work from AEG-Telefunken semiconductor plant in Heilbronn was paid. End of 1981 ended the IRT in Munich, the investigation of the modified for FMbroadcasting HIGH COM FM [30] . The result was cautiously positive, theyrecommended the implementation of field trials.

12th circuit

The AEG and Telefunken with her for some time were in economic difficulties. Mid-1982 announced the Board of AEG-Telefunken finally to compare. It became apparent that the time of the analog signal recording and consequently of thecompander had expired. In March 1983, the digital compact disc was introduced byPhilips and Sony in the marketplace. On 01 April 1983 finally took over the company Thomson in Paris by AEG-Telefunkenfirst 75% of their daughter Telefunken. The headquarters of Deutsche Thomson-BrandtGmbH sat in Villingen in the premises of the previously acquired former HiFi forgeSABA. Thus the fate of the development department in Hanover seemed to be sealed.Emphatically and against strong resistance, the move was driven by Villingen. In timerealized Erich Geiger, the charismatic leader of the DTB, the potential threat lost him togo. He relented and the DTB taught in Hanover in the old rooms on the Telefunken sitea laboratory for digital systems. This should occur more important and lucrative developments, video and audiocodecs, close relatives of the compander. But that's another story.

13th Literature

[1] Scholz, Werner: Narrowband color television transmission in simple terms,Funkschau 1970, Issue 4, pp 109-111

[2] break, Walter: From the slab roller to the image plate, Radio Show, 1977 No.24-1979 No. 10..

[3] Röder, Rolf; Sennheiser: DE2161905 filed on 14/12/1971

[4] Wermuth, Jürgen: DE2403756 filed on 01/26/1974




[8] Wermuth, Jürgen: dynamic expansion through new studio compander 10



Tonmeistertagung Cologne, 19.-11.22.1975

[9] Wermuth, J .; Temmer, St. F .: dynamic expansion through new studiocompander, Funkschau no. 18 (1975) pp 571 ff

[10] Dolby, Ray M .: US3665345, priority GB 21.07.1969

[11] Wermuth, J .; Dickopp, G .; Schröder, E .: DE2529031 filed on 28/06/1975

[12] Jahnel-, Benno: DE2661056 filed on 02/04/1976

[13] Schröder, E .; Wermuth, J .: A new compander - Fundamentals andApplications, Lecture at the FKTG meeting in Freiburg, on 05.10.1976,published in: FCT 30 (1976) No. 12, pp 9-11.

[14] Hoeppner, Dietrich; Hintzmann, Kurt D .; Schroeder, Ernst F .: MonolithicIntegrated NF-compander, Wiss.-Ber. AEG-TELEFUNKEN 52 (1979) 1-2, pp97-104

[15] Mathes, Robert; Western Electric: US1757729, filed on 3/13/1925

[16] CR: compander improves magnetic release, radio mentor No 4 1965 pp 301-303.

[17] Burwen, Richard S .: Design of a Noise Eliminator System, Journal of TheAudio Engineering Society Vol 19 (1971) December pp 906-911

[18] Blackmer, DA: A Wide Dynamic Range Noise Reduction System, db, theSound Eng. Magazine, vol 6, pp 54-56, Aug / Sept 1972

[19] Doba, Stephen; Bell Labs: US2173472, filed on 6/22/1937

[20] Dolby, Ray Milton: An Audio Noise Reduction System, Journal of The AudioEngineering Society 1967 pp 383 ff

[21] Schröder, E .; Wermuth J .: DE2830784 and US4321482, filed on 7/13/1978

[22] Dickopp, Gerhard; Schroeder, Ernst: The Telefunken compander, BroadcastingTechnology Reports Vol 22 (1978), No. 2, pp 63-74

[23] Dickopp, Gerhard; Schroeder, Ernst: Methods of measurement for compander, Funkschau 1978, No. 17, pp 29-32

[24] Scholz, Werner: DE2856045 filed on 23.12.1978

[25] Schroeder, Ernst: DE2919280 filed on 12/05/1979

[26] Mielke, E.-J .: influence of the Dolby B-method to the transmission quality in FMradio broadcasting, Broadcasting Technology Reports Vol 21 (1977) pp 222-228

[27] U401BR, AEG-Telefunken Semiconductor Information 2.80

[28] HIGH COM, Audio Engineering 3 (1981) pp 30 - 35

[29] Handbook CX Low Cost Expander Model E-1016, CBS Technology Center,Stamford, CT, revised August 2, 1981

[30] IRT Technical Report 55/81, testing a modified HighCom-compander for use inthe RF transmission in FM radio, 30.12.1981

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