View source for High Com

{{about|a noise reduction system|the fictional UNSC High Command|HIGHCOM (Factions of Halo)|similarly named topics|Hicom (disambiguation)}}
{{Use dmy dates|date=May 2019|cs1-dates=y}}
{{Use list-defined references|date=December 2021}}
{{bots|deny=Citation bot}}
The '''High&thinsp;Com''' (also as '''HIGH&thinsp;COM''', both written with a thin space<ref group="nb" name="NB_Spelling"/>) [[noise reduction system]] was developed by [[Telefunken]], Germany, in the 1970s as a high quality high compression analogue [[compander]] for audio recordings.
== High&thinsp;Com ==
{| class="wikitable" style="text-align:center;"
|+Compander variants
|-
! Name !! colspan="2"|[[Telefunken telcom c4|telcom&nbsp;c4]] !! High&thinsp;Com !! [[#High Com II|High-Com&nbsp;II]] !! [[#High Com III|High-Com&nbsp;III]] !! [[#High Com FM|High&thinsp;Com&nbsp;FM]]
|-
! Medium
| [[magnetic tape]] || transmission lines, <!-- cable & radio -->links<!-- , satellite systems --><ref name="Kefauver_2001"/> || magnetic tape || magnetic tape,<br />[[vinyl disc]]<ref group="nb" name="NB_Nakamichi_Disk"/> || magnetic tape || [[FM radio broadcasting]]
|-
! Target market
| colspan="2"|professional || consumer || consumer, semi-professional<ref name="Intersonic_1979"/> || semi-professional || consumer
|-
! Development start
| 1971/1972<ref name="Schroeder_2009"/> || ? || 1974<ref name="Schroeder_2009"/> || 1978<ref name="Schroeder_2009"/> || 1978<ref name="Schroeder_2009"/> || 1979<ref name="Schroeder_2009"/>
|-
! Introduction
| 1975/1976<ref name="Schroeder_2009"/> || ? || 1978<ref name="Schroeder_2009"/> || 1979<ref name="Schroeder_2009"/> || never || (1981–1984)
|-
! Compander type
| colspan="2"|linear fixed four-[[frequency band|band]]<ref name="Webers_1989"/> ([[crossover frequency|crossover]]: 215&nbsp;[[Hz]], 1.45&nbsp;kHz, 4.8&nbsp;kHz)<ref name="DAFx_2004"/><ref name="Copeland_2008"/> || [[broadband]] with [[preemphasis|pre]]-/[[deemphasis]]<ref name="Webers_1989"/> from 1.2&nbsp;kHz to 8.6&nbsp;kHz<ref name="DAFx_2004"/> || fixed two-band (crossover: 4.8&nbsp;kHz<ref name="Intersonic_1979"/><ref name="Nakamichi_High-Com_II"/><!-- 4.75 kHz by reverse-engineering -->) with pre-/deemphasis || fixed three-band (crossover: c. 200–400&nbsp;Hz?<!-- guess by Ernst Schröder in 2021 -->, 4.8&nbsp;kHz?<!-- guess by Ernst Schröder in 2021 -->) without pre-/deemphasis<!-- according to Ernst Schröder --> || broadband without pre-/deemphasis<ref name="FT_1984"/>
|-
! Compression
| 1.5:1:1.5<ref name="Webers_1989"/> || 2.5:1:2.5<ref name="Kefauver_2001"/> || 2:1:2<ref name="Webers_1989"/> || 2:1:2<ref name="Intersonic_1979"/> || 2:1:2 || 2:1:2<!-- according to Ernst Schröder -->
|-
! [[Noise reduction]]
| {{nowrap|25–30 [[dB(A)]]<ref name="Webers_1989"/><ref name="Nakamichi_High-Com_II"/><ref name="elektor-UK_1981-70"/>}} || ? || 15–20&nbsp;dB(A)<ref name="Schroeder_2009"/><ref name="AEG_1980_U401BR"/> || 20–25&nbsp;dB(A)<ref name="Nakamichi_High-Com_II"/><ref name="Intersonic_1979"/> || 20–25&nbsp;dB(A)?<!-- guess by Ernst Schröder in 2021 --> || <!-- ?– -->10&nbsp;dB(A)<ref name="Reuber_1983_1"/><ref name="Reuber_1983_2"/><ref name="Shorter_1983"/><ref name="FT_1984"/><ref name="Simon_1984"/>
|-
! [[Calibration tone|Calibration]]&nbsp;/ [[ident tone]]
| alternating 550/650&nbsp;Hz<!-- every half-second -->, −0.13&nbsp;dB, 320&nbsp;nWb/m or 514&nbsp;nWb/m<!-- https://web.archive.org/web/20210430091953/http://rmd.dra.de/arc/ap/ard_hf_wort/rw/regelwerk_wort.pdf --><ref group="nb" name="NB_Telcom_Auto"/> || N/A || originally 440&nbsp;Hz,<ref name="Pütz_1980_HobbyCom"/><ref name="Heiliger_2011"/> later 400&nbsp;Hz, 0&nbsp;dB, 200&nbsp;nWb/m<ref name="Heiliger_2011"/> || 400&nbsp;Hz, 0&nbsp;dB, 200&nbsp;nWb/m<ref name="Nakamichi_High-Com_II"/><ref name="Intersonic_1979"/> || N/A<!-- since never commercialized --> || N/A
|-
! [[Leader tape]]
| 38&nbsp;[[cm (unit)|cm]]/[[s (unit)|s]]: <!-- 10 mm -->red-<!-- 20 mm -->white-<!-- 10 mm -->black-<!-- 5 mm -->white,<ref name="Friedrich_2008"/><ref group="nb" name="NB_Telcom_TapeLeader"/> 19&nbsp;cm/s: <!-- 10 mm -->blue-<!-- 20 mm -->white-<!-- 10 mm -->black-<!-- 5 mm -->white<ref group="nb" name="NB_Telcom_TapeLeader"/> || N/A || N/A || N/A || N/A<!-- since never commercialized --> || N/A
|}
{{anchor|telcom c4}}The idea of a compander for consumer devices was based on studies of a fixed two-[[frequency band|band]] compander by Jürgen&nbsp;Wermuth of [[AEG-Telefunken]] ELA,<!-- Fachbereich Weitverkehr und Kabeltechnik der AEG-Telefunken, Abteilung für professioneller Elektroakustik und Studiotechnik, ELA, Lindener Straße 15, Wolfenbüttel, Germany --> [[Wolfenbüttel]], developer of the Telefunken {{ill|telcom c4|de}} (formally abbreviated as "TEL" in professional broadcasting<ref name="RHW_1993"/>) four-band audio compander for professional use.<ref name="Copeland_2008"/><ref group="nb" name="NB_RFZ"/> {{anchor|RUSW-200}}In April 1974, the resulting "RUSW-200" prototype first led to the development of a sliding two-band compander by Ernst&nbsp;F.&nbsp;Schröder of Telefunken Grundlagenlaboratorium,<!-- Vahrenwalder Straße 215 --> [[Hannover]] since July 1974.
However, the finally released High&thinsp;Com system, which was marketed by Telefunken since 1978, worked as a [[broadband]] 2:1:2 compander, achieving <!-- 10&nbsp;dB to -->almost 15&nbsp;[[Decibel|dB]] of [[noise reduction]] for low<ref name="AEG_1980_U401BR"/> and up to 20&nbsp;dB [[Root mean square|RMS]] [[A-weighted]] for higher frequencies,<ref name="Haase_1980"/><ref name="Schroeder_2009"/><ref name="AEG_1980_U401BR"/><ref name="Pütz_1980_HobbyCom"/> reducing the [[noise power]] down to 1%<!-- compared to 13% for Dolby B --><ref name="Pütz_1980_HobbyCom"/> while avoiding most of the acoustic problems observed with other high compression broadband companders such as [[Elektro-Mess-Technik|EMT]]/NoiseBX, {{ill|Burwen (noise reduction){{!}}Burwen|it|Burwen Noise Eliminator}} or [[dbx (noise reduction)|dbx]].<ref name="Schroeder_2009"/><ref name="Kamm_1980_HobbyCom"/><ref name="Nakamichi_1979_NAK-100"/><ref group="nb" name="NB_Telefunken_Demo-CC"/>
{{anchor|U401}}In order to facilitate cost-effective mass-production in consumer devices such as [[cassette deck]]s, the compander system was integrated into an analogue IC,<ref name="Haase_1980"/> TFK '''U401B'''<ref name="Schroeder_2009"/><ref name="Kamm_1980_HobbyCom"/><ref name="AEG_U401B"/><ref name="Intersonic_1979"/><ref group="nb" name="NB_U401B_Compatibility"/>&nbsp;/ '''U401BG'''<ref name="Schroeder_2009"/><ref group="nb" name="NB_U401B_Compatibility"/>&nbsp;/ '''U401BR''',<ref name="AEG_1980_U401BR"/><ref name="Schroeder_2009"/><ref name="Wiedenroth_1982"/><ref name="Benn_1982"/><ref group="nb" name="NB_U401B_Compatibility"/> developed by Dietrich&nbsp;Höppner and Kurt&nbsp;Hintzmann of {{ill|Telefunken Semiconductors{{!}}AEG-Telefunken Halbleiterwerk|de|Telefunken Semiconductors}}, [[Heilbronn]].<ref name="Schroeder_2009"/><ref name="TFK_1979_U401"/> The chip contained more than 500 transistors.<ref name="Pütz_1980_HobbyCom"/>
With minimal changes in the external circuitry the IC could also be used to emulate a mostly [[Dolby B]]-compatible compander as in the [[Dynamic Noise Reduction|DNR]] (Dynamic Noise Reduction) system<ref name="AEG_1980_U401BR"/> for [[backward compatibility]]. Consequently, second-generation [[tape deck]]s with High&thinsp;Com incorporated a DNR expander as well, whereas in some late-generation Telefunken, ASC and Universum tape decks this even worked during recording, but was left undocumented for legal reasons.
== {{anchor|High Com II|High Com III}}High-Com II and III ==
[[Nakamichi]], one of the more than 25 licensees of the High&thinsp;Com system,<ref name="Schroeder_2009"/><ref name="Intersonic_1979"/> supported the development of a noise reduction system that could exceed the capabilities of the then-prevalent Dolby B-type system. However, it became apparent that a single-band compander without sliding-band technology, which was protected by Dolby patents, suffered too many [[audible artifact]]s. So, High&thinsp;Com was further developed into the two-band '''High&thinsp;Com&nbsp;II''' and three-band '''High&thinsp;Com&nbsp;III'''<ref group="nb" name="NB_Spelling"/> 2:1:2 systems by Werner&nbsp;Scholz and Ernst&nbsp;F.&nbsp;Schröder of Telefunken assisted by Harron&nbsp;K.&nbsp;Appleman of Nakamichi in 1978/1979.<ref name="Schroeder_2009"/><ref name="Schroeder_1979_HighCom_II_III"/><ref name="Nakamichi_1979_NAK-100"/> The two-band variant was eventually released exclusively as ''Nakamichi High-Com&nbsp;II Noise Reduction System'' later in 1979,<ref name="Nakamichi_High-Com_II"/><ref name="Nakamichi_1979_NAK-100"/><ref name="Schroeder_2009"/><ref name="Stereo_1979_Nakamichi"/><ref name="Audio_1979_Nakamichi"/><ref name="Intersonic_1979"/><ref name="KlangBild_1981_Nakamichi"/><ref group="nb" name="NB_Nakamichi_Demo-CC"/><ref group="nb" name="NB_Nakamichi_Demo-LP"/> increasing the amount of noise reduction on analogue recordings and transmissions by as much as <!-- 20&nbsp;dB to -->25&nbsp;dB A-weighted.<ref name="Nakamichi_High-Com_II"/><ref name="Intersonic_1979"/>
== High-Com II for records==
While originally designed for tape recordings, Nakamichi demonstrated the usage of '''High&thinsp;Com&nbsp;II''' on [[LP record]]s as well in 1979.<ref name="Nakamichi_1979_NAK-100"/><ref group="nb" name="NB_Nakamichi_Disk"/><ref group="nb" name="NB_Spelling"/>
In 1982, the same AEG-Telefunken team, who designed the High&thinsp;Com noise reduction system,<ref name="Schroeder_2009"/> also developed the IC [[U2141B]] for the [[CBS Laboratories]] [[CX (audio)|CX]] noise reduction system for LP records,<ref name="Schroeder_2009"/> a system also incorporated into [[FMX (broadcasting)|FMX]], a noise reduction system for [[FM broadcasting]] developed by CBS.
== {{anchor|High Com FM}}High&thinsp;Com FM ==
Similar to the earlier [[Dolby FM]]<ref name="Mielke_1977"/> system in the US, a '''High&thinsp;Com FM''' system was evaluated in Germany between July&nbsp;1979 and December&nbsp;1981 by [[Institut für Rundfunktechnik|IRT]].<ref name="Schroeder_2009"/> It was also considered to be adopted for [[AM broadcasting]].<ref name="HighCom_1982_MW"/> It was based on the High&thinsp;Com broadband compander, but eventually changed to achieve 10&nbsp;dB(A)<ref name="K_1983"/><ref name="Reuber_1983_1"/><ref name="Reuber_1983_2"/><ref name="Shorter_1983"/><ref name="FT_1984"/><ref name="Simon_1984"/> only to improve compatibility with the existing base of receivers without built-in expander.<ref name="K_1983"/><ref name="Shorter_1983"/> The system was field-trialed in public German [[FM broadcasting]] between 1981 and 1984<ref name="IRT_1981"/><ref name="K_1983"/><ref name="Schroeder_2009"/><ref name="HighCom_1982_MW"/><ref name="HighCom_1983_Broadcasting"/><ref name="Porges_1983_FM"/><ref name="HighCom_1983_Test"/><ref name="HighCom_1983_FM"/><ref name="Reuber_1983_1"/><ref name="Reuber_1983_2"/><ref name="HighCom_1983_FM-Comments"/><ref name="Shorter_1983"/><ref name="FT_1984"/><ref name="Simon_1984"/><ref name="HighCom_1984_FM-Decoder"/> and also discussed as an option to be introduced in Austria<ref name="Shorter_1983"/><ref name="ORF_1984_FM"/> and France.<ref name="Shorter_1983"/> However, despite the improvements it was eventually not introduced commercially because of the listening artifacts it created for receivers without expander.<ref name="Spiegel_1984_FM"/><ref name="Ganser_1984_FM"/><ref name="ORF_1984_FM"/><ref name="BR_1984_FM"/>
== Impact ==
{{anchor|CN750|Aiwa|HR-7|HR-50|Rotel|RN-500|RN-1000|SC505|DL506|Hobby-Com|Elektor|Amtron}}Besides Telefunken's own CN&nbsp;750 High&thinsp;Com compander box, other companies also offered external High&thinsp;Com compander boxes such as the [[Aiwa]]<!-- Device is actually named HR-7, not HR-5, check product labels on actual product photos! --> HR-7 and HR-50<!-- known variants HR-50AH, -BH, -E -->, the [[Rotel]] RN-500 and RN-1000,<ref name="Rotel_RN"/><ref group="nb" name="NB_Rotel_Time_constants"/><ref group="nb" name="NB_OEM_Modifications"/> or the Diemme&nbsp;Sonic-distributed Aster&nbsp;Dawn SC&nbsp;505<ref name="SIM_1979_SC505"/><ref name="Diemme-Sonic"/><ref name="SuperStereo"/><ref name="Suono_1980"/><ref group="nb" name="NB_Cieri"/> and the Starsonic DL&nbsp;506, as distributed by D.A.A.F.<!-- also written as "DAAF" and "Daaf" --><ref name="Starsonic_1981_DL506"/><ref name="Sellaria_1981"/><ref name="Cossa_Optionals"/><ref group="nb" name="NB_Cieri"/> A low-cost implementation of the Telefunken High&thinsp;Com system as external compander box became available as ''Hobby-Com'',<ref name="Kamm_1980_HobbyCom"/><ref name="Pütz_1980_HobbyCom"/><ref name="FS_1980_Hobbycom"/> developed by Telefunken product development<ref name="Schroeder_2009"/> and Thomsen-Elektronik<ref name="Kamm_1980_HobbyCom"/> for [[Westdeutscher Rundfunk|WDR]], distributed by <!-- tt vgs -->{{ill|vgs (publisher){{!}}vgs|de|Verlagsgesellschaft Schulfernsehen}},<ref name="Kamm_1980_HobbyCom"/> and promoted for [[do-it-yourself]] assembly in the popular TV series {{ill|Hobbythek|de}} format by [[Jean Pütz]] on 7&nbsp;February&nbsp;1980.<ref name="Kamm_1980_HobbyCom"/><ref name="Schroeder_2009"/> In 1981 and 1982, do-it-yourself High&thinsp;Com kits were introduced from [[elektor]] (''elektor compander''/''Hi-Fi-Kompander'')<ref name="elektor-UK_1981-70"/><ref name="elektor-UK_1981-71"/><ref name="elektor-DE_1981-02"/><ref name="elektor-DE_1981-03"/><ref name="elektor-DE_1981-04"/><ref name="elektor-DE_1982-01"/><ref name="elektor-UK_1982-92"/> and {{ill|G.B.C.<!-- Gian Bruto Castelfranchi -->|it}} Amtron (''micro line High-Com System UK 512 (W<!-- "W" stands for a pre-assembled version rather than a kit -->)'').<ref name="elektor-IT_1981-22"/><ref name="Amtron_1982_UK512"/><ref name="Amtron_1982_C17"/> The only compander available for High-Com&nbsp;II was Nakamichi's own High-Com&nbsp;II<ref group="nb" name="NB_Spelling"/> unit.<ref name="Intersonic_1979"/><ref group="nb" name="NB_Nakamichi_Disk"/>
More than one million High&thinsp;Com systems were sold between 1978 and 1982.<ref name="Wiedenroth_1982"/><ref name="Bruch_1983"/> While implemented in dozens of European and Japanese consumer device models and acoustically much superior to other systems<ref name="Nakamichi_1979_NAK-100"/> such as [[Dolby&nbsp;B]],<ref name="Kamm_1980_HobbyCom"/><ref name="Pütz_1980_HobbyCom"/><ref name="Nakamichi_1979_NAK-100"/><ref name="Bruch_1983"/> [[Dolby&nbsp;C|C]],<ref name="Bruch_1983"/> [[dbx (noise reduction)|dbx]],<ref name="Schroeder_2009"/><ref name="Kamm_1980_HobbyCom"/> {{ill|Automatic Dynamic Range Expansion System{{!}}adres|ja|3=adres}}<ref name="Kamm_1980_HobbyCom"/><ref name="Pütz_1980_HobbyCom"/> or [[Super D (noise reduction)|Super D]],<ref name="Kamm_1980_HobbyCom"/><ref name="Pütz_1980_HobbyCom"/> the High&thinsp;Com family of systems never gained a similar market penetration. This was caused by several factors, including the existing pre-dominance of the Dolby system, with [[Dolby Laboratories]] introducing the "[[Principle of good enough|good enough]]" Dolby&nbsp;C update (with up to 15&nbsp;dB A-weighted improvement) in 1980 as well, and also by the fact that High&thinsp;Com required higher quality tape decks and tapes to work with in order to give satisfactory results.
High-Com&nbsp;II<ref group="nb" name="NB_Spelling"/> even required calibration of the playback level using a 400&nbsp;Hz, 0&nbsp;dB, 200&nbsp;nWb/m<ref name="Nakamichi_1979_NAK-100"/> [[calibration tone]] for optimum results, and with prices in the several hundred dollars for the external Nakamichi compander box it was much too expensive to be used by many people outside the small group of [[audiophile]]s using high-end [[tape recorder]]s or [[open-reel deck]]s.<ref name="Intersonic_1979"/>
When AEG-Telefunken struggled financially in 1981/1982<ref name="Schroeder_2009"/> and the Hannover development site was partially disbanded and refocused on digital technologies in 1983,<ref name="Schroeder_2009"/> this also put the High&thinsp;Com development to an end. The latest tape decks to come with High&thinsp;Com were produced in 1986.
Several software decoders were developed for telcom&nbsp;c4<ref name="Dyson-Hess_2019"/> and High&nbsp;Com,<ref name="Haseborg_2003"/><ref name="DAFx_2004"/><ref name="Schleef_2004"/><ref name="Zander_2009"/><ref name="Dyson-Hess_2019"/> and are considered to be implemented for High-Com&nbsp;II<ref name="Hess_2018"/><ref name="Dyson-Hess_2019"/>
== Tape decks with High&thinsp;Com ==
These tape decks are known to provide built-in support for High&thinsp;Com:<!-- This aims to be a complete list -->
* [[Akai]] GX-F37<ref group="nb" name="NB_Akai_Module"/>
* ASC AS&nbsp;3000
* Rosita Audion D&nbsp;700
* [[Blaupunkt]] XC-240, XC-1400
* ELIN Professional Micro Component Cassette Deck - Modell TC-97
* [[Eumig]] FL-1000μP High&thinsp;Com<ref name="Eumig_FL-1000"/><ref group="nb" name="NB_FL-1000"/>
* Filtronic FSK-200
* [[Grundig]] MCF&nbsp;200, MCF&nbsp;600, CF&nbsp;5100, SCF&nbsp;6200<ref group="nb" name="NB_Grundig_Module"/><ref group="nb" name="NB_OEM_Modifications"/>
* {{ill|hgs ELECTRONIC|d|Q67174276}} Mini Altus HiFi-System Micro Component Stereo Cassette Deck<!-- [https://web.archive.org/web/20210619115802/https://www.picclickimg.com/d/w1600/pict/143932634521_/Cassette-Tape-Deck-ALTUS-mini-Rare.jpg][https://web.archive.org/web/20210619115810/https://www.picclickimg.com/00/s/MTIwMFgxNjAw/z/mokAAOSw7VRgFCIw/$/Cassette-Tape-Deck-ALTUS-mini-Rare-_57.jpg][https://web.archive.org/web/20210619115816/https://www.picclickimg.com/00/s/MTIwMFgxNjAw/z/pqUAAOSwOqtgFCI3/$/Cassette-Tape-Deck-ALTUS-mini-Rare-_57.jpg][https://web.archive.org/web/20210619115822/https://www.picclickimg.com/00/s/MTIwMFgxNjAw/z/QekAAOSwWKBgFCJA/$/Cassette-Tape-Deck-ALTUS-mini-Rare-_57.jpg][https://web.archive.org/web/20210619120000/https://www.picclickimg.com/00/s/MTIwMFgxNjAw/z/AlkAAOSw~eRgFCJJ/$/Cassette-Tape-Deck-ALTUS-mini-Rare-_57.jpg][https://web.archive.org/web/20210619120006/https://www.picclickimg.com/00/s/MTIwMFgxNjAw/z/VB0AAOSwjJVgFCJY/$/Cassette-Tape-Deck-ALTUS-mini-Rare-_57.jpg][https://web.archive.org/web/20210619120011/https://www.picclickimg.com/00/s/MTIwMFgxNjAw/z/P2IAAOSw~kRgFCUE/$/Cassette-Tape-Deck-ALTUS-mini-Rare-_57.jpg][https://web.archive.org/web/20210619120018/https://www.picclickimg.com/00/s/MTIwMFgxNjAw/z/7vMAAOSwWHtgFCJx/$/Cassette-Tape-Deck-ALTUS-mini-Rare-_57.jpg] -->
* [[Hitachi]] D-E75&nbsp;DB/SL
* Imperial TD&nbsp;6100
* [[Intel]] Professional Micro Component Cassette Deck - Modell TC-97
* {{ill|Körting Radio Werke{{!}}Körting|de|Körting Radio Werke}} C&nbsp;102, C&nbsp;220
* [[Revox]] B710 High&thinsp;Com<ref group="nb" name="NB_710"/>
* {{ill|Neckermann (mail order)|de|Neckermann (Versandhandel)|lt=Neckermann}} Palladium Mico Line 2000C<ref name="Palladium_1980"/>
* Nikko ND-500H<ref group="nb" name="NB_OEM_Modifications"/>
* nippon TD-3003
* [[SABA (electronics manufacturer)|Saba]] <!-- LOGIC CONTROL CASSETTE DECK -->CD278<!-- without space -->, <!-- logic control cassette deck -->CD&nbsp;362<!-- with space -->, CD&nbsp;363<!-- with space -->
* [[Schneider Rundfunkwerke AG|Schneider]] SL&nbsp;7270&nbsp;C
* Sencor SD-6650
* [[Siemens]] RC&nbsp;333, RC&nbsp;300
* [[Studer]] A710 High&thinsp;Com<ref name="Studer_A710"/><ref group="nb" name="NB_710"/>
* [[Telefunken]] TC&nbsp;750,<ref name="Schroeder_2009"/> TC&nbsp;450, TC&nbsp;450M,<ref name="Palladium_1980"/> TC&nbsp;650, TC&nbsp;650M, STC&nbsp;1 / CC&nbsp;20, MC&nbsp;1, MC&nbsp;2, HC&nbsp;700, HC&nbsp;800, HC&nbsp;1500,<ref name="Schroeder_2009"/> HC&nbsp;3000, HC&nbsp;750M, HC&nbsp;730T, RC&nbsp;100, RC&nbsp;200, RC&nbsp;300, Hifi Studio 1, Hifi Studio 1M, Studio Center 5004<!-- High Com -->, Studio Center 5005<!-- High Com -->, Studio Center 7004<!-- High Com --><ref name="Telefunken_TC_750"/>
* [[Tensai International|Tensai]] TFL-812
* [[Uher (company)|Uher]] CG&nbsp;321, CG&nbsp;325, CG&nbsp;344, CG&nbsp;356, CG&nbsp;365, mini-hit
* {{ill|Quelle (Mail order company){{!}}Quelle|de|Quelle (Versandhandel)}} {{ill|Universum (brand){{!}}Universum|de|Universum (Handelsmarke)}} Senator CT&nbsp;2307, Senator CT&nbsp;2307A, CT&nbsp;2318 (for SYSTEM HIFI 7500&nbsp;SL), Senator CT&nbsp;2337, Senator VTCF&nbsp;407<!-- (for SYSTEM HIFI 7000) --><!-- same as Telefunken Studio Center 7004 -->
* Wangine K-3M, WSK-120, WSK-220
Other devices can be used with an external High&thinsp;Com compander box.
== See also ==
* [[CX (noise reduction)|CX]] (Compatible Expansion), another disk noise reduction system
* [[dbx (noise reduction)|dbx]], a competing noise reduction system
* [[Dolby noise reduction system]]
* [[Dolby SR]] (Spectral Recording)
* [[Dynamic Noise Reduction]] (DNR), a playback-only noise reduction system often confused with Dolby
* [[FMX (broadcasting)]], another FM noise reduction system
* [[UC (noise reduction)|UC]] (Universal Compatible), another disk noise reduction system
== Notes ==
{{Reflist|group="nb"|refs=
<ref group="nb" name="NB_Spelling">[[Telefunken]]'s official spelling of the name was "High&thinsp;Com" (also as "HIGH&thinsp;COM"), both written with a thin space. However, Nakamichi's official spelling of their variant of Telefunken's High&thinsp;Com&nbsp;II was "High-Com II". Many independent German authors would use "{{lang|de|High-Com}}" also for Telefunken's system because of a grammar feature called ''{{ill|Durchkopplung|de}}''. [[Compound (linguistics)|Compound]]s are concatenated without space in German. Compounds, which can't be combined without a space for linguistical reasons, are concatenated with a hyphen instead. Since High&thinsp;Com is a compound, the correct German spelling in normal prose would be "{{lang|de|High-Com}}" despite Telefunken's alternative spelling. This holds true even more for further combinations such as "{{lang|de|High-Com-System}}" (rather than "{{lang|de|High&thinsp;Com-System}}" or "{{lang|de|High&thinsp;Com System}}").</ref>
<ref group="nb" name="NB_U401B_Compatibility">The [[Telefunken]] TFK&nbsp;U401B [[integrated circuit]] was available in five revisions: TFK&nbsp;U401B chips with a yellow dot are equivalent to the U401BG. TFK&nbsp;U401BG chips with a blue dot are equivalent to the TFK&nbsp;U401BR. TFK&nbsp;U401BR chips with yellow dot as well as yellow and blue dots exist also.<!-- with unknown changes compared to the undotted version --> Yet another revision was planned to incorporate the changes to Telefunken's High&thinsp;Com system since about 1982 to no longer require external circuit modifications, but was apparently never released. These revisions were also used on Telefunken's own High&thinsp;Com modules, which were available in various assembly variants (for example BS&nbsp;5335&nbsp;/ AT&nbsp;349&nbsp;355&nbsp;003 or BS&nbsp;5356&nbsp;/ AT&nbsp;349&nbsp;355&nbsp;024) and also used in many third-party products. [https://web.archive.org/web/20171208222337/http://saba-forum.dl2jas.com/index.php/Thread/6729-Telefunken-STC-1-Cassettendeck-19-STC1/?pageNo=2<!-- showing U401BR with yellow dot -->][https://web.archive.org/web/20171209140436/http://www.bilder-hochladen.net/files/big/c4q7-lf-c94c.jpg<!-- showing third-party modules with U401BR with yellow and blue dots -->][https://web.archive.org/web/20171209141413/http://www.bilder-hochladen.net/files/big/c4q7-lg-d609.jpg<!-- back side of third-party module -->][https://web.archive.org/web/20170721081333/http://www.suess-online.de:80/technik/TelefunkenRC300/HighCom/highcom_modifikationen.htm][https://web.archive.org/web/20200711224841/http://saba-forum.dl2jas.com/index.php/Thread/7524-HIGH-COM-IC-U401B-Beschaltung-TELEFUNKEN/?pageNo=2&s=e900f0c3ad2df72a21a01f356d2292a0f9cbcaf8]</ref>
<ref group="nb" name="NB_710">The [[Studer]] A710 was alternatively available with either [[Telefunken]] High&thinsp;Com and [[Dynamic Noise Reduction|DNR]] (PCB 1.710.483-00<!-- encoder 1983-02-17 -->&nbsp;+ 1.710.493-00<!-- decoder 1982-10-27 --> each based on two TFK&nbsp;U401BR), or with [[Dolby&nbsp;B]] and [[Dolby C|C]] (PCB 1.710.489-00<!-- encoder 1983-02-17 -->&nbsp;+ 1.710.492-00<!-- decoder 1982-05-03 --> each based on two HA&nbsp;12038) noise reduction modules and front plates. Likewise, the very similar [[Revox]] B710 was alternatively available in High&thinsp;Com and Dolby&nbsp;B versions, but could be factory-upgraded to support both, Dolby B and C after the release of the Revox B710 Mk&nbsp;II model, which featured Dolby B and C only as well.</ref>
<ref group="nb" name="NB_FL-1000">The [[Eumig]] FL-1000μP was alternatively available with either the [[Dolby&nbsp;NR]] (type B) or the [[Telefunken]] High&thinsp;Com noise reduction system and corresponding front plates.</ref>
<ref group="nb" name="NB_Nakamichi_Disk">The [[Nakamichi]] High-Com&nbsp;II Noise Reduction System exists in two very similar but functionally slightly different versions: One variant has a special "Disk" mode setting to decode High-Com&nbsp;II encoded [[vinyl disc]]s without having to pass the encoded signal through a connected tape deck first, whereas the other variant makes it slightly easier to activate the 400&nbsp;Hz calibration tone and allows the [[Subsonic filter|Subsonic]] and [[MPX filter|MPX]] input filters to be activated at the same time. [https://web.archive.org/web/20171208002910/https://www.vinylengine.com/turntable_forum/viewtopic.php?f=18&t=91925]</ref>
<ref group="nb" name="NB_Telcom_Auto">Some ''telcom c4'' companders have a "Telcom Auto" setting which would automatically activate or bypass the telcom c4 system depending on if the telcom [[ident tone]] alternating between 550&nbsp;Hz and 650&nbsp;Hz every 500&nbsp;ms was detected on the [[leader tape]] or not. [https://web.archive.org/web/20171208174925/http://forum.studerundrevox.de/viewtopic.php?f=8&t=3087&start=20]</ref>
<ref group="nb" name="NB_Telcom_TapeLeader">The colored [[leader tape]]s standardized (for example in "{{lang|de|Technisches Pflichtenheft 3/9 der öffentlich-rechtlichen Rundfunkanstalten in der Bundesrepublik Deutschland}}" or the later "{{lang|de|Technische Richtlinie 3/9 Vorspann-, Zwischen- und Endbänder für Schaltzwecke im Studio}}" (as of February 1987) by [[Institut für Rundfunktechnik|IRT]] and the German public broadcasting industry indicating a record using [[Telefunken]]'s telcom c4 system are defined as a sequence of 10&nbsp;mm red ([[RAL 3000]]), 20&nbsp;mm white ([[RAL 9010]]), 10&nbsp;mm black ([[RAL 9011]]) and 5&nbsp;mm white for 38&nbsp;cm/s recordings, and 10&nbsp;mm blue ([[RAL 5007]]), 20&nbsp;mm white, 10&nbsp;mm black and 5&nbsp;mm white for 19&nbsp;cm/s. For possible detection utilizing a [[transmissiometer]], the white, red and blue tape stripes must provide a transparency between 27% and 60% in contrast to less than 8% for the black stripes and the magnetic tape itself. The colors must be facing the [[magnetizable coating]] / [[tape head]] side of the tape.[https://web.archive.org/web/20210430015447/https://www.irt.de/fileadmin/media/Neue_Downloads/Publikationen/Technische_Richtlinien/3_9.pdf][https://web.archive.org/web/20171208013834/http://tonbandinfo.magnetofon.de/index.php?topic=2137.msg16973]</ref>
<ref group="nb" name="NB_Akai_Module">The High&thinsp;Com module for the [[Akai]] GX-F37 was named BA-T2017A050A (CL-5602) and contained two Telefunken TFK&nbsp;U401BR chips.<!-- https://www.ebay.de/itm/AKAI-BA-T2017A050A-Original-High-Com-PCB-Platine-f-Tape-Deck-GX-F37-NOS-T2-2/223461333029?hash=item3407555825:g:C5wAAOSw6wxcmj9Q --></ref>
<ref group="nb" name="NB_Grundig_Module">The High&thinsp;Com module for one<!-- yet unknown --> [[Grundig]] tape deck was named KPL-39302-942 / 39302-946 and contained one Telefunken TFK&nbsp;U401BR chip.<!-- not yet known if one or two modules were needed per tape deck --><!-- https://www.ebay.de/itm/2x-Grundig-High-Com-Modul/164262496430?hash=item263ecec8ae:g:M6sAAOSwo8te05MV --></ref>
<ref group="nb" name="NB_Cieri">The companders ''Aster Dawn Stereo Compander SC&nbsp;505'' and ''Starsonic High-Com Noise Reduction System DL&nbsp;506'' were developed by Quirino Cieri, manufactured by two art shops and distributed through Diemme Sonic and D.A.A.F., both residing at Jacopo Palma 11, Milano, Italy at the time. Both companders were available in black and silver case finish. [https://web.archive.org/web/20200702192535/http://www.cieri.net/miei_progetti.html<!-- Quirino Cieri: "A fine anni '70 avevo progettato alcuni componenti speciali audio, che sono stati poi realizzati da due ditte artigianali milanesi ed esposte alla principale fiera di settore di quel periodo (il SIM Hi-Fi di Milano). Qui riporto alcune presentazioni e recensioni di questi componenti speciali, fatte da alcune riviste di settore dell'epoca." -->][https://web.archive.org/web/20200702180353/https://www.ebay.it/itm/Amplificatore-audio-mixer-a-semiconduttori-STARSONIC-DL-506-ottime-condizioni/164126577414?hash=item2636b4d306:g:6scAAOSwY4Neb1mf]</ref>
<ref group="nb" name="NB_Telefunken_Demo-CC">{{anchor|64.22029|64.22089|64.21824|64.21972}}[[Telefunken]] / [[TELDEC]] provided four High&thinsp;Com demonstration and test records labelled "High&thinsp;Com. Das neue Stör- und Rauschunterdrückungs-System. Von Telefunken." on ferro-magnetic ([[IEC type I]]) [[cassette tape]]s with bias 120&nbsp;μs: "Eine Meß-Cassette." (64.22029): 1. Level tone 400&nbsp;Hz 200&nbsp;nWb/m, 2. [[Pink noise]] High&thinsp;Com encoded (level −30&nbsp;dB<sub>eff</sub> below 200&nbsp;nWb/m without compander); "Eine Demonstrations-Cassette." (64.21824)<!-- track list same as B. in: -->, and "Eine Meß- und Demonstrations-Cassette." (64.21972): A. Calibration advice with measurement tone, B. 1. [[Richard Strauss]] [[Till Eulenspiegel's Merry Pranks|Till Eulenspiegel]], 2. [[Beethoven]] Wo O. 16,[[#Suffix-star|<sup>[*]</sup>]] 3. [[Rimsky-Korssakoff]] [[Capriccio Espagnol]], 4. [[Franz Schubert|Schubert]]–{{ill|Günter Noris{{!}}Noris|de|Günter Noris}} Serenade, 5. Studio take II.[[#Suffix-star|<sup>[*]</sup>]][[#Suffix-starstar|<sup>[**]</sup>]] There also was a "Eine Demonstrations-Cassette." (64.22089) variant on Agfa Superchrome ([[IEC type II]]) cassette tape with bias 70&nbsp;μs and changed track order: A. 1. Beethoven: Klavier-Konzert Nr. 5 Es-dur, 2. Beethoven: Fidelio Gefangenen-Chor, 3. Rimsky-Korssakoff Capriccio Espagnol, 4. Berlioz: Symphonie Fantastique scene "Ein Ball", 5. Chiquitita/Stanley Black, 6. "L'animal" from the film "Ein irrer Typ", 7. Studio take.<!-- B. empty --> {{anchor|Suffix-star}}<sup>[*]</sup>Telcom c4 studio material. {{anchor|Suffix-starstart}}<sup>[**]</sup>Comment on sleeve: Musicians and sound engineer before recording while tuning instruments and electronics. Even the hum of a defective amplifier is audible. (NB. There also was an earlier version of the calibration tape containing a 440&nbsp;Hz rather than a 400&nbsp;Hz test tone.{{citeref|Heiliger|2011|A}}{{citeref|Pütz|Gollhardt|1980|B}})</ref>
<ref group="nb" name="NB_Nakamichi_Demo-CC">{{anchor|S008|T-480305}}In 1979, [[Nakamichi]], in cooperation with [[Three Blind Mice Records, Inc.]], offered a High-Com II demonstration tape S&nbsp;008&nbsp;/ T-480305, a limited edition not-for-sale High&thinsp;Com II encoded audiophile [[cassette tape]] sample recorded at 4.8&nbsp;cm/s (1-7/8&nbsp;ips) on a Nakamichi Metalloy Direct Cassette ZX C-15 with [[Fujifilm|Fuji]] IEC type-IV [[metal tape]] with bias 70&nbsp;μs. The tracks included on side A: 1. Little Step ([[Masaru Imada Quartet]]), 2. New Orleans Sunday ({{ill|Shoji Yokouchi{{!}}Shōji Yokouchi Trio|de|Shōji Yokouchi}} & Yuri Tashiro), side B: ?.<!-- A similar demo record was later also offered for Dolby C: Metalloy Tape ZX C-15 Demo Tape 70μs JASRAC Metalloy Sound T-5B0903 S013 --></ref>
<ref group="nb" name="NB_Nakamichi_Demo-LP">{{anchor|Tracks-NAK-100}}Track list of [[Nakamichi]] High-Com II demonstration record [[#NAK-100|NAK-100]]: Side A: [[Philharmonia Hungarica]] ([[Zoltan Rozsnyai]]): 1. [[Bizet]] ([[Carmen]] prelude) [2:30] 2. [[Berlioz]] ([[Rákóczi March]] from [[The Damnation of Faust|Damnation of Faust]]) [4:40] 3. [[Rimsky-Korsakov]] (Procession of the Nobles from [[Mlada (Rimsky-Korsakov)|Mlada]]) [4:55] 4. [[Brahms]] ([[Hungarian Dance No. 5]]) [4:30] 5. 400&nbsp;Hz calibration tone. [1:00], Side B: [[S.M.A. Sextet]] ([[Sherman Martin Austin]]): 1. [[Impressions (John Coltrane album)|Impressions]] ([[John Coltrane]]) [5:00] 2. Mimosa ([[Dennis Irwin]]) [5:52] 3. Little B's Poem ([[Bobby Hutcherson]]) [3:12] 4. 400&nbsp;Hz calibration tone [1:00].</ref>
<ref group="nb" name="NB_Rotel_Time_constants">{{anchor|Rotel-time-constants}}[[Rotel]]'s High&thinsp;Com companders RN-500 and RN-1000 used other [[time constant]]s than Telefunken's High&thinsp;Com, thereby rendering the encoded material incompatible with other High&thinsp;Com companders. Early Rotel units internally used Telefunken High&thinsp;Com modules with two parts exchanged (R7&nbsp;=&nbsp;3.3&nbsp;MΩ instead of 8.2&nbsp;MΩ, C7&nbsp;=<!-- no typo! -->&nbsp;33&nbsp;μF&nbsp;/&nbsp;16&nbsp;V instead of 0.22&nbsp;μF&nbsp;/&nbsp;16&nbsp;V), whereas later units used their own circuitry. [https://web.archive.org/web/20200711183242/http://saba-forum.dl2jas.com/index.php/Thread/7524-HIGH-COM-IC-U401B-Beschaltung-TELEFUNKEN/][https://web.archive.org/web/20200711224841/http://saba-forum.dl2jas.com/index.php/Thread/7524-HIGH-COM-IC-U401B-Beschaltung-TELEFUNKEN/?pageNo=2&s=e900f0c3ad2df72a21a01f356d2292a0f9cbcaf8][https://web.archive.org/web/20200711231741/http://saba-forum.dl2jas.com/index.php/Thread/7524-HIGH-COM-IC-U401B-Beschaltung-TELEFUNKEN/?pageNo=3][https://web.archive.org/web/20200711232355/http://saba-forum.dl2jas.com/index.php/Thread/7524-HIGH-COM-IC-U401B-Beschaltung-TELEFUNKEN/?pageNo=4]</ref>
<ref group="nb" name="NB_OEM_Modifications">Not all OEMs followed [[Telefunken]]'s High&nbsp;Com specifications rigorously. Besides [[Rotel]]'s changes of the [[#Rotel-time-constants|time constant]]s, [[Grundig]] and Nikko also introduced changes to the circuitry. [https://web.archive.org/web/20200711224841/http://saba-forum.dl2jas.com/index.php/Thread/7524-HIGH-COM-IC-U401B-Beschaltung-TELEFUNKEN/?pageNo=2&s=e900f0c3ad2df72a21a01f356d2292a0f9cbcaf8]</ref>
<ref group="nb" name="NB_RFZ">Between 1987 and 1990, the East-German {{ill|Rundfunk- und Fernsehtechnisches Zentralamt{{!}}RFZ|de|Rundfunk- und Fernsehtechnisches Zentralamt}} in Leipzig developed a number of telcom c4-compatible companders like the 8-channel NV&nbsp;2180 (for {{ill|Mechlabor|hu|Mechanikai Laboratórium Híradástechnikai Kísérleti}} STM-700 etc.), the 8-channel NV&nbsp;2180/1, the 4-channel NV&nbsp;2181, the 2-/4-channel NV&nbsp;2181/1 (with NV&nbsp;2180&nbsp;L1 cards), or the 2-channel VTR/MAZ compander NV&nbsp;2182.</ref>
}}
== References ==
{{Reflist|refs=
<ref name="Schroeder_2009">{{cite web |author-first=Ernst&nbsp;F. |author-last=Schröder |title=The Story of HIGH&thinsp;COM |date=2009 |orig-date=2007 |url=http://www.ernstschroeder.de/highcom.htm |access-date=2016-04-16 |url-status=live |archive-url=https://web.archive.org/web/20160416153816/http://www.ernstschroeder.de/highcom.htm |archive-date=2016-04-16}} [https://web.archive.org/web/20200812130706/http://www.ernstschroeder.de/highcom_d.htm]</ref>
<ref name="Heiliger_2011">{{cite web |author-first=Jürgen |author-last=Heiliger |title=Telefunken CN&nbsp;750 High&thinsp;Com |language=de |date=2011-08-18 |url=http://forum2.magnetofon.de/board2-tonbandger%C3%A4te/board15-hilfe-tipps-rund-um-das-tonbandger%C3%A4t/12643-telefunken-cn-750-high-com-heftiges-pumpen#post132808 |access-date=2017-12-08 |url-status=unfit |archive-url=https://web.archive.org/web/20171208041249/http://forum2.magnetofon.de/board2-tonbandger%C3%A4te/board15-hilfe-tipps-rund-um-das-tonbandger%C3%A4t/12643-telefunken-cn-750-high-com-heftiges-pumpen/?s=9038780c04a059aca8dceb506ece364a518f269f |archive-date=2017-12-08 |quote=[…] Auf der normalerweise beiliegenden Einmesskassette war ein Testton von 400&nbsp;Hz mit 200&nbsp;nWb/m ([[#64.22029|neuere Version]]) oder 440&nbsp;Hz mit 200&nbsp;nWb/m (erste Version). […]}}</ref>
<ref name="AEG_U401B">{{cite book |publisher=[[Telefunken]] |title=Telefunken Databook 1979/1980 |chapter=U&nbsp;401&nbsp;B HIGH&thinsp;COM Monolithisch Integrierte Schaltung / Monolithic Integrated Circuit |language=de, en |id=S8/V2.711/0279AI |edition=preliminary |pages=81–83 |url=https://www.tvsat.com.pl/pdf/U/u401b_tfk.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210425173255/https://www.tvsat.com.pl/pdf/U/u401b_tfk.pdf |archive-date=2021-04-25}} [https://web.archive.org/web/20210425173252/https://www.web-bcs.com/pdf/Tf/U4/U401B.pdf<!-- https://www.web-bcs.com/pdf/Tf/U4/U401B.pdf -->] (3 pages)</ref>
<ref name="AEG_1980_U401BR">{{cite journal |author-last=Schröder |author-first=Ernst F. |publisher=[[AEG-Telefunken]] |title=HIGH&thinsp;COM - The HIGH&thinsp;COM broadband compander utilizing the U401BR integrated circuit |work=Semiconductor Information |volume=80 |number=2 |id=2.80 |date=1980 |url=http://www.ernstschroeder.de/u401br.pdf |access-date=2016-04-16 |url-status=live |archive-url=https://web.archive.org/web/20160416153706/http://www.ernstschroeder.de/u401br.pdf |archive-date=2016-04-16}}</ref>
<ref name="Nakamichi_1979_NAK-100">{{anchor|NAK-100}}{{cite book |date=1979 |publisher=[[Nakamichi]] |title=The Stillness of Dawn - High-Com II Demonstration Record |id=NAK-100 |type=A limited edition not-for-sale High&thinsp;Com II encoded audiophile [[vinyl record]] and corresponding leaflet. This [[LP record|LP]] contains 400&nbsp;Hz, 0&nbsp;dB, 200&nbsp;nWb/m calibration tones as well. |quote="Quotes from the sleeve: […] Thousands of man-hours were spent listening, adjusting, optimizing&mdash;until harpsichords sound like harpsichords without mutilated [[transient (acoustics)|transient]]s, until bass viols sound like bass viols without [[harmonic distortion]], until triangles sound lean and crisp without [[breathing (noise reduction)|breathiness]]. The result is High-Com II, the world's finest ''two-band'' noise-reduction system. […] High-Com II is the first ''audiophile'' noise-reduction system that achieves ''professional'' quality. […] Listen especially for the dramatic reduction in [[surface noise]] on this High-Com II encoded record. There is no residual [[tape hiss|hiss]]; the ticks, pops, and [[crackling (noise)|crackle]]s that mar conventional discs are absent. So is [[turntable rumble]]. The loud passages emerge with unprecedented clarity since they need not be recorded at so high and distortion-producing a level. […] Between programs, there is utter silence. […] We also suggest you listen closely for sounds of "breathing" and [[noise pumping]]. This common fault of noise-reduction systems has been eliminated in High-Com II. Listen also to High-Com II's remarkable ability to accurately preserve musical transients. They are neither muted nor exaggerated nor edgy as with other companders. This accuracy of reproduction&mdash;on all types of music, at all frequencies, and at all levels&mdash;is what distinguishes High-Com II from other noise-reduction systems. […] Unlike simple companders, High-Com II is optimized differently for signals of different strength and different frequencies. Low-level signals are processed for maximum noise reduction, high-level ones for minimum distortion. This sophisticated technique assumes maximum [[dynamic range]] with minimum "breathing" and other audible side effects. […] Sound of extraordinary dynamic range&mdash;a background free from surface noise, pops, [[clicking noise|click]]s, rumble, and [[groove echo]]&mdash;the mightiest crescendo, free from distortion. Sound without breathing, pumping, or other ill side effects."}} (NB. For the track list see [[#Tracks-NAK-100|here]].)</ref>
<ref name="Mielke_1977">{{cite journal |author-last=Mielke |author-first=E.-Jürgen |date=1977 |title=Einfluß des Dolby-B-Verfahrens auf die Übertragungsqualität im UKW-Hörrundfunk |language=de |trans-title=Influence of Dolby B system on the quality of transmission in FM radio broadcasting |journal=Rundfunktechnische Mitteilungen (RTM) |publisher=[[Institut für Rundfunktechnik]] (IRT) |volume=21 |pages=222–228}}</ref>
<ref name="IRT_1981">{{cite book |date=1981-12-30 |publisher=[[Institut für Rundfunktechnik]] (IRT) |id=Technical Report 55/81 |title=Prüfung eines modifizierten HIGH&thinsp;COM-Kompanders für den Einsatz bei der RF-Übertragung im UKW-Hörfunk |language=de |trans-title=Evaluation of a modified HIGH&thinsp;COM compander for usage in the RF transmission in FM radio broadcasting}}</ref>
<ref name="Kamm_1980_HobbyCom">{{cite journal |author-first1=Dieter |author-last1=Kamm |author-first2=Jean |author-last2=Pütz |author-link2=Jean Pütz |editor-first1=Brigitte |editor-last1=Reis |editor-first2=Gerhard |editor-last2=Praßer |title=High-Com, Hobby-Com - Für Hifi-Freunde: Musikgenuss ohne Rauschen |language=de |trans-title=High-Com, Hobby-Com - For Hi-Fi fans: Enjoying music without noise |date=March 1980 |volume=56 |publisher=[[Westdeutscher Rundfunk|WDR]] |journal=Hobbytip der Hobbythek |url=http://joerg.brehme.org/wp-content/uploads/2014/09/056-Musikgenuss-ohne-Rauschen.pdf |access-date=2017-11-05 |url-status=live |archive-url=https://web.archive.org/web/20171105104647/http://joerg.brehme.org/wp-content/uploads/2014/09/056-Musikgenuss-ohne-Rauschen.pdf |archive-date=2017-11-05}}</ref>
<ref name="Pütz_1980_HobbyCom">{{cite book |editor-first1=Jean |editor-last1=Pütz |editor-link1=Jean Pütz |editor-first2=Heinz |editor-last2=Gollhardt |title=Das Hobbythek-Buch 4 |date=1980 |isbn=3-80256103-1 |id={{ISBN|978-3-80256103-0}}<!-- Leave these ISBNs alone! --> |volume=4 |chapter=6. Musikgenuß ohne Rauschen |language=de |trans-title=Enjoying music without noise |publisher={{ill|vgs (publisher){{!}}Das Köln Verlagsgesellschaft Schulfernsehen / vgs|de|Verlagsgesellschaft Schulfernsehen}} |pages=127–145}} (19 of 152+4 pages)</ref>
<ref name="Wiedenroth_1982">{{cite magazine |author-first=Bernd |author-last=Wiedenroth |title=High-Com-Modifikationen |language=de |trans-title=High&thinsp;Com modifications |magazine={{ill|Funkschau|de}} - Elektronik in Audio und Video, Kommunikation und Meßtechnik |date=December 1982<!-- second issue in December --> |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |issue=26 |volume=54 |page=69 <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol54num26/ -->|url=http://www.suess-online.de/technik/TelefunkenRC300/HighCom/highcom_modifikationen.htm |access-date=2017-11-05 |url-status=dead |archive-url=https://web.archive.org/web/20171105134610/http://www.suess-online.de/technik/TelefunkenRC300/HighCom/highcom_modifikationen.htm |archive-date=2017-11-05 |quote-page=69 |quote=[…] Die Modifikation des Systems High-Com sieht für diesen Störfall statt der bisher mit einer Zeitkonstante arbeitende Regelspannungs-Speicherschaltung eine Zwei-Zeitkonstantenschaltung vor. Die bessere Wirkung beruht darauf, dass bei Knackstörungen kurzer Dauer nur eine erste Teilkapazität geladen wird. Die erste Teilkapazität wird sich durch Umladung auf die zweite, zehnmal größere und durch einen Widerstand entkoppelte Teilkapazität, wieder schnell entladen, nachdem die Knackstörung vorüber ist. Die Dimensionierung ist so vorgenommen worden, dass bei Nutzsignalspitzen, selbst bei höchsten Nf-Frequenzen, keine wahrnehmbare Veränderung des Einschwingverhaltens auftritt. […] Die Systemmodifikation sieht deshalb eine Verdopplung der bei vorhandenem Signal wirksamen Abklingzeitkonstanten vor, wodurch sich diese Klirrwerte halbieren. Mit der im System enthaltenen Zeitkonstantenumschaltung bei schnellem Signalabfall kann diese Modifikation ohne den hörbaren Nachteil der kritischen Rauschfahnen erfolgen, da die verlängerte Zeitkonstante nur bis zu 30ms nach Signalende wirksam ist und danach auf eine wesentlich kürzere Zeitkonstante umgeschalten wird. […] Die Dimensionierung des Systems hinsichtlich der Werte für die Haltezeit und für die kurze Abklingzeitkonstante zeigte sich auch unter Beachtung der möglichen Toleranzfälle und der hörphysiologischen Gegebenheiten des menschlichen Hörvermögens als gelungen. Die Systemmodifikation setzt in diesem Fall nicht bei der Dimensionierung der Zeitwerte ein, sondern es wird der zeitliche Übergang der abklingenden Regelspannung optimiert. In der bisherigen Systemauslegung wurde beim Erkennen des schnellen Pegelabfalls (nach Ablauf der Haltezeit) abrupt von der langen Abklingzeitkonstante auf den kurzen Wert umgeschaltet. Dies hatte zur Folge, dass bereits wenige Millisekunden nach diesem Vorgang relativ große Verstärkungsänderungen auftraten. Daraus ergab sich im Falle von "Drop-outs" oder stärkerem "Mistracking" die Gefahr hörbarer Dynamikfehler (teilweise auch als "Pumpen" bezeichnet). Die Systemmodifikation ergibt für den genannten Wechsel von langer zu kurzer Zeitkonstante einen weichen Übergang. Diese Änderung wird auch als Verrundung oder "soft-switching" bezeichnet und bewirkt eine wesentliche Beruhigung des dynamischen Systemverhaltens, so dass selbst unter kritischen Signal- und Toleranzbedingungen, eine in der Praxis vollständige Maskierung der zuvor geschilderten Gegebenheiten eintritt. […] Die Systemmodifikationen sind vorerst mit einer Zusatzbeschaltung des ICs U401BR realisierbar. Zukünftig ist eine Änderung der integrierten Schaltung U401BR beabsichtigt. Eine Layout-Änderung des ICs ist in Bearbeitung, wobei in diesem Falle nur eine geringfügige Änderung der Peripheriebeschaltung notwendig wird. […]}} [https://web.archive.org/web/20210424033418/http://www.stefankneller.de/elektronik/zaehlwerk/softswitching.html<!-- http://www.stefankneller.de/elektronik/zaehlwerk/softswitching.html -->][https://web.archive.org/web/20200701123207/https://www.ebay.de/itm/Zwei-U401-BR-HighCom-ICs-TFK-mit-Soft-Switching-Modul-Raritaet-/143618123440?epid=636721371&hash=item21704ea6b0%253Ag%253AF24AAOSw1QReqfJU&nma=true&si=4bSM%25252BRw0X%25252Bo%25252FjKoXf%25252FSeTyvaqNg%25253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557][https://web.archive.org/web/20200701124831/https://www.ebay.de/itm/Zwei-U401-BR-HighCom-ICs-TFK-mit-Soft-Switching-Modul-Raritat/143645140402?hash=item2171eae5b2:g:KRkAAOSwqUJe-Mqe]</ref>
<ref name="Benn_1982">{{cite magazine |author-first=Dietrich |author-last=Benn |title=Test High&thinsp;Com: Die Reifeprüfung - Telefunkens modifiziertes High&thinsp;Com CN&nbsp;750 |language=de |magazine=stereoplay |issn=0172-388X |publication-place=Stuttgart, Germany |publisher={{ill|Motor Presse Stuttgart{{!}}Vereinigte Motor-Verlage|de|Motor Presse Stuttgart}} |issue=1 |date=January 1982 |pages=40–<!-- –40?/41?/42? -->}}</ref>
<ref name="Telefunken_TC_750">{{cite web |title=Telefunken TC 750 - HiFi Stereo Recorder - 1979 - 1981 |url=http://www.vintagecassette.com/Telefunken/TC_750 |access-date=2017-11-05 |url-status=live |archive-url=https://web.archive.org/web/20171105135824/https://www.vintagecassette.com/Telefunken/TC_750 |archive-date=2017-11-05}}</ref>
<ref name="Rotel_RN">{{cite web |title=Rotel High&thinsp;Com Noise Reduction System RN-1000 RN-500 - owner's manual |pages=1–7 |url=http://bwgroupsupport.com/downloads/manuals/rotel/RN-500-OM.pdf |access-date=2017-11-14 |url-status=live |archive-url=https://web.archive.org/web/20171114212453/http://bwgroupsupport.com/downloads/manuals/rotel/RN-500-OM.pdf |archive-date=2017-11-14}}</ref>
<ref name="Copeland_2008">{{cite web |title=Manual of Analoque Sound Restoration Techniques |author-first=Peter |author-last=Copeland |publisher=The British Library Sound Archive (www.bl.uk) |location=London, UK |date=February 2009 |orig-date=September 2008 |editor-first=Gert |editor-last=Redlich |via=Deutsches Hifi-Museum, Wiesbaden, Germany |at=Chapter 9. Reciprocal noise reduction |url=http://www.hifimuseum.de/sound-restoration-teil-9.html |access-date=2017-11-05 |url-status=live |archive-url=https://web.archive.org/web/20171105193837/http://www.hifimuseum.de/sound-restoration-teil-9.html |archive-date=2017-11-05}} (NB. Copeland was strongly biased from a British perspective, but nevertheless very knowledgeable.)</ref>
<ref name="Nakamichi_High-Com_II">{{cite book |title=Nakamichi High-Com II Noise Reduction System - Owner's Manual - Bedienungsanleitung - Mode d'Emploi |language=en, de, fr |date=1980 |id=0D03897A, O-800820B |url=http://manualmachine.com/nakamichi/high-com-ii/1156333-user-manual/ |access-date=2017-11-10 |url-access=limited |url-status=dead |archive-url=https://web.archive.org/web/20171110221440/http://manualmachine.com/nakamichi/high-com-ii/1156333-user-manual/page:2/ |archive-date=2017-11-10  }} [https://web.archive.org/web/20210505181108/https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Nakamichi-High-Com-II-Owner-Manual.pdf]</ref>
<ref name="TFK_1979_U401">{{cite journal |author-last1=Höppner |author-first1=Dietrich |author-last2=Hintzmann |author-first2=Kurt D. |author-last3=Schröder |author-first3=Ernst F. |title=Monolithisch integrierte NF-Kompander |journal=Wissenschaftliche Berichte |publisher=[[AEG (German company)|AEG-TELEFUNKEN]] |volume=52 |date=1979 |number=1–2 |pages=97–104}}</ref>
<ref name="Palladium_1980">{{cite magazine |date=November 1980 |magazine={{ill|Audio (German magazine){{!}}Audio|de|Audio#Zeitschrift}}<!-- not the same as the English magazine --> |title=Frei Haus |language=de |url=http://forum2.magnetofon.de/board13-verst%C3%A4rker-phono-decks/board61-cassetten-decks/5148-universum-von-telefunken/index2.html?s=bce62783acbdfe0a18a42e7c008e2a0032ee5bb2#post81962 |access-date=2017-11-13 |url-status=live |archive-url=https://web.archive.org/web/20171113140354/http://forum2.magnetofon.de/board13-verst%C3%A4rker-phono-decks/board61-cassetten-decks/5148-universum-von-telefunken/index2.html?s=bce62783acbdfe0a18a42e7c008e2a0032ee5bb2 |archive-date=2017-11-13}}</ref>
<ref name="Eumig_FL-1000">{{cite book |title=Eumig FL1000μP Cassettendeck - Die Cassetten-Tonbandmaschine |type=Product flyer |language=de |id=939.540/4 |url=http://wegavision.pytalhost.com/Eumig/eumigFL1000p/EumigFL1000Info_04.jpg |access-date=2017-11-13 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20171113202308/http://wegavision.pytalhost.com/Eumig/eumigFL1000p/ |archive-date=2017-11-13  }}</ref>
<ref name="Studer_A710">{{cite book |title=Studer A710 Professional Cassette Tape Recorder - Service-Anleitung - Service Instructions - Instructions de service |date=1984 |orig-date=1980 |language=de, en, fr |url=ftp://ftp.studer.ch/Public/Products/Recording_Analog/A710/Manuals/A710_Serv.pdf |access-date=2019-08-13 |url-status=dead |archive-url=https://web.archive.org/web/20151211042954/ftp://ftp.studer.ch/Public/Products/Recording_Analog/A710/Manuals/A710_Serv.pdf |archive-date=2015-12-11}}</ref>
<ref name="Stereo_1979_Nakamichi">{{cite magazine |title=Nakamichi High-Com II |magazine={{ill|Stereo (magazine){{!}}Stereo|de|Stereo (Zeitschrift)}} |language=de |date=November 1979 |volume=1979 |number=11}}</ref>
<ref name="Audio_1979_Nakamichi">{{cite magazine |title=Nakamichi High-Com II |magazine={{ill|Audio (German magazine){{!}}Audio|de|Audio#Zeitschrift}}<!-- not the same as the English magazine --> |language=de |date=December 1979 |volume=1979 |number=12}}</ref>
<ref name="KlangBild_1981_Nakamichi">{{cite journal |title=Nakamichi High-Com II |journal=KlangBild |language=de |date=June 1981 |volume=1981 |number=6}}</ref>
<ref name="FS_1980_Hobbycom">{{cite magazine |title=Hobbycom (High-Com): Testbericht |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=1980-06-20 |issue=13 |volume=52 |pages=97– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol52num13/ -->}}</ref>
<ref name="elektor-DE_1981-02">{{cite magazine |title=Rauschunterdrückung - der Physik ein Schnippchen schlagen! (HighCom, Prinzip) |language=de |date=February 1981 |volume=1981 |issue=2 |magazine=[[elektor (German magazine)|elektor]] |publisher=[[Elektor Verlag GmbH]] |issn=0932-5468 |id={{CODEN|ELKRCM}} |pages=24– |url=https://www.elektormagazine.de/magazine/elektor-198102/46220 |url-access=registration}}</ref>
<ref name="elektor-UK_1981-70">{{cite magazine |title=High Com - the latest noise reduction system / Noise reduction - silence is golden |date=February 1981 |volume=1981 |issue=70 |magazine=[[elektor (English magazine)|elektor]] – up-to-date electronics for lab and leisure |issn=1757-0875 |publisher=[[Elektor Publishers Ltd.]] |language=en |pages=2-04–2-09 |url=https://worldradiohistory.com/UK/Elektor/80s/Elektor-1981-02.pdf |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20200702122034/https://worldradiohistory.com/UK/Elektor/80s/Elektor-1981-02.pdf |archive-date=2020-07-02}} (6 pages)</ref>
<ref name="elektor-DE_1981-03">{{cite magazine |title=Elektor Hi-Fi-Kompander: Rauschen - ade! (2 HighCom-Module U401BR) |language=de |date=March 1981 |volume=1981 |issue=3 |magazine=[[elektor (German magazine)|elektor]] |publisher=[[Elektor Verlag GmbH]] |issn=0932-5468 |id={{CODEN|ELKRCM}} |pages=56– |url=https://www.elektormagazine.de/magazine/elektor-198103/46238 |url-access=registration}}</ref>
<ref name="elektor-IT_1981-22">{{cite magazine |title=Amtron - Kits elettronici |language=it |type=Advertisement |date=March 1981 |volume=2 |number=22 |magazine=[[elektor (Italian magazine)|elektor]] – elettronica - scienza tecnica e diletto |issn= |publisher={{ill|Jacopo Castelfranchi Editore|it|Jacopo Castelfranchi}} (JCE) |pages=3–13 |url=https://www.rsp-italy.it/Electronics/Magazines/Elektor/_contents/Elektor%201981-03%2022.pdf |access-date=2020-07-12 |url-status=live |archive-url=https://web.archive.org/web/20200712090107/https://www.rsp-italy.it/Electronics/Magazines/Elektor/_contents/Elektor%201981-03%2022.pdf |archive-date=2020-07-12}}</ref>
<ref name="elektor-UK_1981-71">{{cite magazine |title=the High Com noise reduction system |date=March 1981 |volume=1981 |issue=71 |magazine=[[elektor (English magazine)|elektor]] – up-to-date electronics for lab and leisure |issn=1757-0875 |publisher=[[Elektor Publishers Ltd.]] |language=en |pages=3-06–3-17 |url=https://worldradiohistory.com/UK/Elektor/80s/Elektor-1981-03.pdf |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20200702132734/https://worldradiohistory.com/UK/Elektor/80s/Elektor-1981-03.pdf |archive-date=2020-07-02}} (12 pages)</ref>
<ref name="elektor-DE_1981-04">{{cite magazine |title=Nachtrag HiFi Kompander |language=de |date=April 1981 |volume=1981 |issue=4 |magazine=[[elektor (German magazine)|elektor]] |publisher=[[Elektor Verlag GmbH]] |issn=0932-5468 |id={{CODEN|ELKRCM}} |pages=58–}}</ref>
<ref name="elektor-DE_1982-01">{{cite magazine |title=Elektor HiFi-Kompander: Monitor - Hinterbandkontrolle für Drei-Kopf-Geräte |language=de |date=January 1982 |issue=1 |volume=1982 |magazine=[[elektor (German magazine)|elektor]] |publisher=[[Elektor Verlag GmbH]] |issn=0932-5468 |id={{CODEN|ELKRCM}} |pages=1–30–1-?? |url=https://www.elektormagazine.de/magazine/elektor-198201/46418/ |url-access=registration}}</ref>
<ref name="elektor-UK_1982-92">{{cite magazine |title=Soft switching - improvement to the High Com - based on information from the Telefunken Television and Radio Company, Audio Development |date=December 1982 |volume=1982 |issue=92 |magazine=[[elektor (English magazine)|elektor]] – up-to-date electronics for lab and leisure |issn=1757-0875 |publisher=[[Elektor Publishers Ltd.]] |publication-place=Canterbury, UK |language=en |pages=2–41 |url=https://worldradiohistory.com/UK/Elektor/80s/Elektor-1982-12.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210309191951/https://worldradiohistory.com/UK/Elektor/80s/Elektor-1982-12.pdf |archive-date=2021-03-09 |quote=[…] 1. […] the distortion content of the first harmonic of a sinusoidal 20&nbsp;Hz signal is reduced by about 6% and that of the second harmonic by 3.5%. The total distortion factor with the new version is only 3.31%, compared to 10.38% with the old version. The improvement was achieved by increasing the decay time which is effective during the holding time. […] 2. Interference caused by very short pulses, such as electrostatic discharges when playing records, is now eliminated by modifying the response time of the circuit. The network for this function now contains two time constants instead of one. This greatly improves the compander's capability and has been demonstrated by the better response time on a sinusoidal 10&nbsp;kHz burst. 3. Short dropouts result in undesirable, audible fluctuations in level. The High&thinsp;Com circuit sometimes responded to these drop-outs with uncontrolled regulating effects. […] On the other hand, the type of noise effects in signal pauses that are familiar with other noise suppression systems could not be heard. Telefunken achieves this performance by controlling the decay with a long time constant during the holding time, followed by a short time constant. However, this automatic changeover between the two time constants was so abrupt that it sometimes resulted in the effects mentioned. Our soft switching circuit eliminates these problems, even with critical signals. […]}} [https://www.elektormagazine.com/index.php/magazine/elektor-198212/44975] (1 page)</ref>
<ref name="Amtron_1982_UK512">{{cite web |title=Amtron micro line High-Com System UK 512 |date=1983 |orig-date=1982 |url=https://www.radiomuseum.org/r/amtron_high_com_system_micro_line_uk_512.html |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20200702130306/https://www.radiomuseum.org/r/amtron_high_com_system_micro_line_uk_512.html |archive-date=2020-07-02}} (NB. Advertised in 1982/1983 Amtron catalog in Italy.)</ref>
<ref name="Amtron_1982_C17">{{cite book |title=Amtron Kuriuskit - kits elettronici 1982–83 |language=it |chapter=Riduttore Di Fruscio High-Com System UK 512 W |volume=17 |type=Catalog |publisher={{ill|G.B.C.<!-- Gian Bruto Castelfranchi-->|it}} Amtron |location=Milano, Italy |date=1983 |orig-date=1982 |pages=2, 10 |url=http://puppylinux.ath.cx:4085/webserver/Amtron/catalogs/Amtron%20-%20Kuriuskit%20-%20Catalogo%20Kit%201982-1983.pdf |access-date=2020-07-12 |url-status=dead |archive-url=https://web.archive.org/web/20170813185054/http://puppylinux.ath.cx:4085/webserver/Amtron/catalogs/Amtron%20-%20Kuriuskit%20-%20Catalogo%20Kit%201982-1983.pdf |archive-date=2017-08-13 |quote-page=10 |quote=[…] Tensione di funzionamento: 18V […] Corrente di funzionamento: 80&nbsp;mA […] Banda passante: 40&nbsp;Hz + 17&nbsp;kHz […] Resistenza d'ingresso: * compressione: 5,6&nbsp;KΩ * espansione: 50&nbsp;KΩ […] Resistenza d'uscita in espansione: 5&nbsp;KΩ […] Rapporto S/N ingresso AMP: 80&nbsp;dB […] Sensibilità d'ingresso DIN: 0,2&nbsp;mV/per ogni KΩ d'ingresso […] Riduzione di fruscio: 20&nbsp;dB […] Distorsione totale: < 0,1% a 1&nbsp;kHz […] SM/1512-07 […]}}</ref>
<ref name="Haseborg_2003">{{cite book |title=Untersuchung und Implementierung von Kompanderverfahren für eineAudiodatenübertragung |author-first=Jan Remmer |author-last=ter Haseborg |type=diploma thesis |publisher=[[Technische Universität Hamburg-Harburg]] |date=June 2003}}</ref>
<ref name="DAFx_2004">{{cite journal |journal=Proceedings of the 7th International Conference on Digital Audio Effects (DAFx'04) |location=Naples, Italy |date=2004-10-05 |title=Digital Emulation of Analog Companding Algorithms for FM Radio Transmission |author-first1=Jürgen |author-last1=Peissig |author-first2=Jan Remmer |author-last2=ter Haseborg |author-first3=Florian |author-last3=Keiler |author-first4=Udo |author-last4=Zölzer |pages=285–290 |url=http://ant-s4.unibw-hamburg.de/dafx/paper-archive/2004/P_285.PDF |access-date=2017-11-14 |url-status=live |archive-url=https://web.archive.org/web/20171114210416/http://ant-s4.unibw-hamburg.de/dafx/paper-archive/2004/P_285.PDF |archive-date=2017-11-14}}</ref>
<ref name="Schroeder_1979_HighCom_II_III">{{cite journal |author-last=Schröder |author-first=Ernst F. |title=2-Band und 3-Band Kompander nach dem Kettenverstärkerprinzip (HIGH&thinsp;COM II und HIGH&thinsp;COM III) |language=de |publisher=[[Telefunken Fernseh- und Rundfunk GmbH]] |journal=Laborbericht |date=1979}} [https://web.archive.org/web/20210429234040/http://www.dafx.de/paper-archive/2004/P_285.PDF] (6 pages)</ref>
<ref name="HighCom_1982_MW">{{cite magazine |title=High-Com bei MW-Übertragung |language=de |magazine={{ill|Funkschau|de}} - Elektronik in Audio und Video, Kommunikation und Meßtechnik |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=October 1982<!-- third issue in October --> |issue=22 |volume=54 |pages=61– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol54num22/ -->}}</ref>
<ref name="Porges_1983_FM">{{cite journal |author-last1=Porges |author-first1=Ivan |author-last2=Schröder |author-first2=Ernst F. |title=Ein kompatibles Kompandierungsverfahren für FM-Rundfunk und dessen schaltungstechnische Realisierung |language=de |series=NTG-Fachberichte #83 |publisher={{ill|Nachrichtentechnische Gesellschaft|de}} (NTG) / [[Verband Deutscher Elektrotechniker]] (VDE) |publication-place=Berlin / Offenbach, Germany |date=1983 |journal=Hörrundfunk |issue=6 |pages=151–158}}</ref>
<ref name="HighCom_1983_Broadcasting">{{cite magazine |title=High-Com im Rundfunk: Empfang verbessern |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=August 1983<!-- second issue in August --> |issue=17 |volume=55 |pages=50– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol55num17/ -->}}</ref>
<ref name="HighCom_1983_Test">{{cite magazine |title=High-Com im Rundfunk: Plädoyer für den Feldversuch |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=December 1983<!-- first issue in December --> |issue=25 |volume=55 |pages=44– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol55num25/ -->}}</ref>
<ref name="HighCom_1983_FM">{{cite magazine |title=High-Com FM; Großversuch |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=December 1983<!-- second issue in December --> |issue=26 |volume=55 |pages=11– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol55num26/ -->}}</ref>
<ref name="HighCom_1984_FM-Decoder">{{cite magazine |title=High-Com-FM-Decoder für High-Com-FM-Feldversuch |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=1984-02-03 |issue=3 |volume=56 |pages=74– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol56num3/ -->}}</ref>
<ref name="Ganser_1984_FM">{{cite journal <!-- |description= -->|title=High-Com-UKW: Bericht von Otto Ganser über den ARD-Versuch |language=de |author-first=Otto |author-last=Ganser |date=1984-02-03<!-- 9:00–9:46 --> |journal=BNL-Radioshow |type=broadcasting |number=82}}<!-- https://web.archive.org/web/20200702085227/https://olaf.robbenradio.de/Archiv10.pdf --> [6:20 min]</ref>
<ref name="ORF_1984_FM">{{cite journal |title=Hörfunk weiterhin ohne High Com |language=de |date=October–November 1984 |volume=1984 |issue=9 |series=Aktuelles aus dem In- und Ausland |journal=ORF Technikum – Fortbildungsdienst für alle Technikbereiche |publisher=[[Österreichischer Rundfunk]] (ORF), Generalintendanz / Schulung und Dokumentation}}</ref>
<ref name="BR_1984_FM">{{cite book |title=Geschäftsbericht 1984 – Geschäftsbericht des Bayerischen Rundfunks 1984 |language=de |chapter=1. Studio- und Außenübertragungstechnik – 1.1. Hörfunk |publisher=[[Bayerischer Rundfunk]] (BR) |date=1984 |page=46 |url=https://www.br.de/unternehmen/inhalt/geschichte-des-br/geschaeftsbericht-br-1984-100~attachment.pdf?&usg=AOvVaw0VOr6Wr8uQOtuzEG0yBKl1 |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20200702082043/https://www.br.de/unternehmen/inhalt/geschichte-des-br/geschaeftsbericht-br-1984-100~attachment.pdf?usg=AOvVaw0VOr6Wr8uQOtuzEG0yBKl1 |archive-date=2020-07-02 |quote-page=46 |quote=[…] Die Ausstrahlungsversuche mit dem Rauschunterdrückungsverfahren High&thinsp;Com&nbsp;FM wurden abgeschlossen. In den vergangenen Jahren hatten sich die deutschen Rundfunkanstalten intensiv mit diesem Systemvorschlag zur Verminderung des Rauschens auf dem Funkübertragungswege zwischen UKW-Sender und Rundfunkteilnehmer beschäftigt. Insbesondere das [[Institut für Rundfunktechnik]] in München stellte umfangreiche Untersuchungen dazu an. Auch die Betriebsleiterkonferenzen der Rundfunkanstalten für die Bereiche Hörfunk und Sendertechnik beteiligten sich eingehend an den entsprechenden Überlegungen und Betrachtungen. Die ursprüngliche Erwartung, mit dem System High&thinsp;Com&nbsp;FM Qualitätsverbesserungen im UKW-Hörfunk sowie eine Verbesserung der Übertragungstechnik in den Versorgungsrandgebieten erreichen zu können, bestätigte sich nicht im gewünschten Ausmaß. Die Technische Kommission von [[ARD (broadcaster)|ARD]] und [[ZDF]] legte daraufhin fest, dieses Rauschunterdrückungsverfahren nicht einzuführen. Dieser Entscheidung war ein ausgiebiger bundesweiter Feldversuch in den ersten drei Monaten des Jahres 1984 vorangegangen, an dem auch der Bayerische Rundfunk mit einer UKW-Senderkette teilnahm. […]}}</ref>
<ref name="HighCom_1983_FM-Comments">{{cite magazine |title=Rundfunktechnik: High-Com-FM-Feldversuch - Anmerkungen |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=April 1984<!-- first issue in April --> |issue=8 |volume=56 |pages=69– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol56num8/ -->}}</ref>
<ref name="Bruch_1983">{{cite magazine |author-first=Walter |author-last=Bruch |author-link=Walter Bruch |title=Von der Tonwalze zur Bildplatte (Teil II) - Entwicklung der Magnetbandtechnik |series=100 Jahre Ton- und Bildspeicherung |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=September–October 1983<!-- first, second, third issue in September and first issue in October --> |volume=55 |issue=18, 19, 20, 21 <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol55num18/ https://www.radiomuseum.org/lf/p/funkschau/vol55num19/ https://www.radiomuseum.org/lf/p/funkschau/vol55num20/ https://www.radiomuseum.org/lf/p/funkschau/vol55num21/ --> |url=http://www.magnetbandmuseum.info/w-bruch-artikel-nr70.html |access-date=2017-12-08 |url-status=live |archive-url=https://web.archive.org/web/20171208161529/http://www.magnetbandmuseum.info/w-bruch-artikel-nr70.html |archive-date=2017-12-08}}</ref>
<ref name="Spiegel_1984_FM">{{cite magazine |title=Rundfunk - Singende Säge |language=de |author=<!-- staff writer, no byline --> |magazine=[[Der Spiegel]] |issue=23 |volume=1984 |date=1984-06-04 |pages=76, 78 |url=https://www.spiegel.de/spiegel/print/d-13507788.html |access-date=2020-07-01 |url-status=live |archive-url=https://archive.today/20200701131914/https://www.spiegel.de/spiegel/print/d-13507788.html |archive-date=2020-07-01}} (2 pages) [https://magazin.spiegel.de/EpubDelivery/spiegel/pdf/13507788<!-- https://web.archive.org/web/20200703141738/https://magazin.spiegel.de/EpubDelivery/spiegel/pdf/13507788 -->]</ref>
<ref name="Webers_1989">{{cite book |title=Tonstudiotechnik: Schallaufnahme und -wiedergabe bei Rundfunk, Fernsehen, Film und Schallplatte |language=de |chapter=E.2.4.2 Das Telcom-System: Der "telcom c4"-Kompander / Das High-Com-System |author-first=Johannes |author-last=Webers |edition=5th extended |date=1989 |isbn=3-7723-5525-0 |publisher=[[Franzis-Verlag GmbH]] |series=Franzis Handbuch |publication-place=Munich, Germany |pages=329–334}} (758+2 pages)</ref>
<ref name="SIM_1979_SC505">{{cite magazine |title=13° SIM - High Fidelity 1979 |language=it |date=October 1979 |magazine={{ill|Discoteca Hi-Fi|it}} |type=Report |location=Milano, Italy |url=http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20&%20Starsonic%20-%20Reportage%2013%C2%B0SIM.pdf |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20131021065308/http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20&%20Starsonic%20-%20Reportage%2013%C2%B0SIM.pdf |archive-date=2013-10-21}} (2 pages)</ref>
<ref name="Starsonic_1981_DL506">{{cite magazine |title=nei tuoi nastri musica+dinamica (senza fruscio) - Compandea Starsonic High Com DL 506 |language=it |date=May 1981 |magazine={{ill|Discoteca Hi-Fi|it}} |location=Milano, Italy |type=Advertisement |page= |url=https://www.radiomuseum.org/r/starsonic_high_com_dl506.html |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20200702115108/https://www.radiomuseum.org/r/starsonic_high_com_dl506.html |archive-date=2020-07-02}} (1 page)</ref>
<ref name="Cossa_Optionals">{{cite magazine |title=Gli Optionals Starsonic |language=it |series=Accessori |author-first=Piero |author-last=Cossa |via=Personal web site of Quirino Cieri |magazine= |volume= |date= |type=Review |pages=22–23, 24?<!-- perhaps 25? --> |url=http://www.cieri.net/Documenti/Miei%20progetti/Starsonic%20-%20Gli%20optionals%20Starsonic%20(recensione).pdf |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20131021070320/http://www.cieri.net:80/Documenti/Miei%20progetti/Starsonic%20-%20Gli%20optionals%20Starsonic%20(recensione).pdf |archive-date=2013-10-21}} (3 pages)</ref>
<ref name="Diemme-Sonic">{{cite news |title=Poco rumore a poco |language=it |author=((Diemme Sonic)) |location=Milano, Italy |newspaper= |date= |via=Personal web site of Quirino Cieri |url=http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20-%20High-Com%20-%20Poco%20rumore%20a%20poco.pdf |access-date=2020-07-02 |url-status=bot: unknown |archive-url=https://archive.today/20200702185542/http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20-%20High-Com%20-%20Poco%20rumore%20a%20poco.pdf |archive-date=2020-07-02  }}</ref>
<ref name="SuperStereo">{{cite news |title=High Com - Arriva L'Aster Down |language=it |author=((Diemme Sonic)) |location=Milano, Italy |newspaper={{ill|SuperStereo|it|Superstereo}} |series=Notizie |date= |via=Personal web site of Quirino Cieri |url=http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20-%20High-Com%20-%20Arriva%20l%27Aster%20Dawn.pdf |access-date=2020-07-02 |url-status=bot: unknown |archive-url=https://archive.today/20200702185714/http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20-%20High-Com%20-%20Arriva%20l'Aster%20Dawn.pdf |archive-date=2020-07-02  }} (NB. The title contains a typo and should read "High Com - Arriva L'Aster Dawn" instead.)</ref>
<ref name="Suono_1980">{{cite news |title=Italiano, economico, separato, High-Com |language=it |author=((Diemme Sonic)) |location=Milano, Italy |newspaper=Suono |number=93 |date=May 1980 |via=Personal web site of Quirino Cieri |url=http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20-%20High-Com%20-%20Presentazione%20su%20Suono%20N.93%20(05-1980).pdf |access-date=2020-07-02 |url-status=live |archive-url=https://archive.today/20200702185403/http://www.cieri.net/Documenti/Miei%20progetti/Aster%20Dawn%20-%20High-Com%20-%20Presentazione%20su%20Suono%20N.93%20(05-1980).pdf |archive-date=2020-07-02}}</ref>
<ref name="Sellaria_1981">{{cite magazine |title=Compander stereo STARSONIC DL506 |language=it |author-first=Marco |author-last=Sellaria |date=1981 |issue=1 |id=No. 169 |magazine={{ill|CQ elettronica{{!}}cq elettronica|it|CQ elettronica}} - speciale prove OM e CQ - supplemento omaggio al n. 169 di cq elettronica |publication-place=Bologna, Italy |page=59 |url=http://www.introni.it/pdf/suppl%20CQ%20elettronica%201981_01.pdf |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20160911124355/http://www.introni.it/pdf/suppl%20CQ%20elettronica%201981_01.pdf |archive-date=2016-09-11}}</ref>
<ref name="Friedrich_2008">{{cite book |title=Tontechnik für Mediengestalter: Töne hören - Technik verstehen - Medien gestalten |language=de |author-first=Hans Jörg |author-last=Friedrich |location=Stuttgart, Germany |chapter=(II.) 11.2.2. Aufnahme- und Übertragungstechnik: Die Schallplatte |date=2008 |publisher=[[Springer-Verlag]] |publication-place=Berlin / Heidelberg, Germany |edition=1 |isbn=978-3-540-71869-7 |series=X.media.press |issn=1439-3107 |doi=10.1007/978-3-540-71870-3 |page=164: Table 11.1 |chapter-url=https://books.google.com/books?id=_78fBAAAQBAJ&pg=PA164 |access-date=2020-07-04 |quote-page=164 |quote=[…] schwarz-weiß-rot […] Stereo […] 15&nbsp;Zoll/Sekunde […] Rauschunterdrückung Telcom C4 […]}} (xvii+346 pages) (NB. The cited leader tape colors are incomplete, other sources cite the pattern black-white-red as for 15&nbsp;inch/s stereo with [[timecode]].)</ref>
<ref name="Intersonic_1979">{{cite book |title=Nakamichi High Com II |author=Nakamichi |author-link=Nakamichi |publisher=Intersonic Elektrohandelsges. m.&nbsp;b.&nbsp;H.&nbsp;& Co. |type=Flyer |publication-place=Hamburg, Germany |language=de |via=hifi-wiki.de |url=https://www.hifi-wiki.de/index.php/Nakamichi_High_Com_II |access-date=2021-04-24 |url-status=live |archive-url=https://web.archive.org/web/20210423204912/https://www.hifi-wiki.de/index.php/Nakamichi_High_Com_II |archive-date=2021-04-23 |quote=[…] Die maximalen Änderungsgeschwindigkeiten der Verstärkung wurden für das jeweilige Frequenzband verschieden gewählt: […] Einschwingzeit: [[low-pass filter|Tiefband]] 0,3&nbsp;ms […] [[high-pass filter|Hochband]] 0,15&nbsp;ms […] Ausschwingzeit: Tiefband 180&nbsp;ms&nbsp;+ 25&nbsp;ms Haltezeit […] Hochband 50&nbsp;ms […] Die Zeitkonstanten wurden so bemessen, daß der hierdurch eintretende systembedingte Klirrfaktor weder bei der Kompression noch bei der Expansion 1% überschreiten kann. Der typische Wert liegt bei 0,2%. […] Die optimale Übertragungsfrequenz der zwei Bänder wurde nach intensiven Hörversuchen für 4,8&nbsp;kHz ermittelt. Um Phasenverschiebungen auszuschließen wurden für die Übergangsfrequenz Filter mit 6&nbsp;dB/Oktave im Signalweg gewählt. Die Linearität wird dadurch gewährleistet, daß die Gleichrichter mit aktiven 12&nbsp;dB/Okt[ave-]Filtern angesteuert werden, und sich so eine ges[amte] Flankensteilheit von 18&nbsp;dB/Okt[ave] ergibt. […] Eine sehr wichtige Forderung an ein Kompandersystem ist die Unempfindlichkeit gegenüber Toleranzen. Diese Unempfindlichkeit ist beim High&thinsp;Com&nbsp;II in zweifacher Hinsicht verwirklicht: zum einen basiert High&thinsp;Com&nbsp;II auf einem Schaltungsprinzip bei dem es nur auf die Verhältnisse von Bauelementen zueinander ankommt, während die Toleranzen der absoluten Werte ohne Einfluß bleiben. Zum anderen ist High&thinsp;Com&nbsp;II aber auch relativ unempfindlich gegenüber Toleranzen des Übertragungskanals. Dies im Gegensatz zu den heute weit verbreiteten Sliding-Band-Kompandern. Stimmt der Pegel am Eingang des Expanders nicht, so kommt es bei Sliding-Band-Kompandern zu einer Klangbildverfälschung. Entweder zu einer Höhenanhebung oder einer Höhenabsenkung. Beim High&thinsp;Com&nbsp;II bleibt die Spektralbewertung dagegen völlig unverändert, sogar bei Pegelverfälschungen von bis zu ±6&nbsp;dB. Es bleibt lediglich ein Dynamikfehler übrig, der sich im Wesentlichen in einer Lautstärke-Änderung äußert. Um diesem Umstand vorzubeugen hat Nakamichi in das High&thinsp;Com&nbsp;II System einen 400&nbsp;Hz-[[calibration tone|Test-Ton-Generator]] integriert. Eine einfache Anpassung an alle [[cassette deck|Cassetten-Decks]] oder [[Reel-to-reel audio tape recorder|Spulentonbandmaschinen]] ist mit Hilfe der großen [[VU meter|VU-Meter]] leicht möglich. […] Neben dem Einsatz im Bereich der kommerziellen Unterhaltungsindustrie ist das High&thinsp;Com&nbsp;II vor allem auch als kostengünstige Alternative im professionellen Studiobereich anzusehen. Beim Einsatz von 24-Kanal-Bandmaschinen ergibt sich gegenüber herkömmliche[n] Rauschunterdrückungssystemen ein erheblicher Preis[-]Leistungs-Vorsprung. Nakamichi erwägt daher z.Zt. die Produktion von High&thinsp;Com&nbsp;II Printplatten, die mechanisch mit denen eines [[Dolby A|Dolby-A]]-Systems kompatibel sind. […] Das Nakamichi High&thinsp;Com&nbsp;II basiert auf den [ICs] U&nbsp;401&nbsp;B von [[Telefunken]]. Nakamichi ist weltweit der einzige Lizenznehmer der High&thinsp;Com&nbsp;II Entwicklung, da diese gemeinsam von Telefunken und Nakamichi geleistet wurde. […]}}</ref>
<ref name="Haase_1980">{{cite magazine |title=Rauschunterdrückung: Kampf dem Rauschen |language=de |department=Systeme und Konzepte |author-first=Hans-Joachim |author-last=Haase |location=Aschau, Germany |magazine=Funk-Technik - Fachzeitschrift für Funk-Elektroniker und Radio-Fernseh-Techniker <!-- Gegründet von Curt Rint -->- Offizielles Mitteilungsblatt der Bundesfachgruppe Radio- und Fernsehtechnik |issn=0016-2825 |publisher={{ill|Dr. Alfred Hüthig Verlag GmbH|de|Hüthig GmbH}} |publication-place=Heidelberg, Germany |date=August 1980 |volume=35 |issue=8 |pages=W293–W296, W298, W300 [W296] |url=http://docplayer.org/206765376-Neuer-wickel-auf-bewaehrtem-kerr.html |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210516054234/http://docplayer.org/206765376-Neuer-wickel-auf-bewaehrtem-kerr.html |archive-date=2021-05-16 |quote-pages=W296 |quote=[…] High Com ist ein Breitband-Kompander […] Die Probleme der Kalibrierung treten bei dem von Telefunken entwickelten High-Com-Rauschunterdrückungsverfahren nicht auf. Weil es im Gegensatz zum Dolby-Verfahren gleichmäßig im gesamten Tonfrequenzbereich wirksam ist, bezeichnet man es als Breitband-Kompander-System. Eine typische Eigenschaft solcher schon in den 50er-Jahren im Bereich der Tonstudiotechnik versuchsweise eingesetzten, meist sehr aufwendigen Breitband-Kompander-Systeme ist das Hörbarwerden der in Abhängigkeit von den schwankenden Eingangssignalen ablaufenden Regelvorgängen, die man als Atmen bezeichnet. Die Systeme konnten sich daher seinerzeit nicht durchsetzen und wurden in verbesserter Form erst in jüngster Zeit wieder auf den Markt gebracht (zum Beispiel Telcom C4). Für den Konsum-Bereich speckten die Telefunken-Entwickler das Telcom-C4-System ab und es entstand das High-Com-System, das keine besonderen Bedien- und Justier-Vorgänge mehr erfordert. Durch geschickte schaltungstechnische Maßnahmen konnte auch das störende Atmen verhindert werden. Die umfangreichen elektronischen Funktionen sind in einem hochintegrierten IC untergebracht, so daß der serienmäßige Einbau der kleinen Platinen auch in preiswerten Hi-Fi-Cassetten-Recordern bald zur Regel werden könnte. […] Bei der schaltungstechnischen Konzeption des High-Com-ICs wurde davon Gebrauch gemacht, daß durch wechselweises Verwenden desselben ICs und durch Einbeziehen derselben externen Bauelemente in den Kompressions- und Expansionsvorgang unvermeidbare Bauteil-Toleranzen sich spiegelbildlich kompensieren und ein Frequenzgang erreicht wird, der nur noch von der Qualität des eigentlichen Aufzeichnungs- und Wiedergabevorgangs abhängig ist. […] Die nach Anwendung des High-Com-Systems noch verbleibende Rauschleistung wird auf 1% (20 dB) des Ursprungswertes herabgesetzt. Auch die tieffrequenten Störungen, wie Grund- und Oberwellen der Netzfrequenz werden im gleichen Maße mit abgesenkt. Praktisch steht nun auch bei Cassetten-Recordern ein Dynamik-Bereich von über 80 dB zur Verfügung […]}}</ref>
<ref name="Reuber_1983_1">{{cite magazine |title=Hörfunk in Zukunft - Erst High-Com, dann digital |language=de |department=Aktuelle Grundsatzfragen |author-first=Claus |author-last=Reuber |magazine=Funk-Technik - Fachzeitschrift für Funk-Elektroniker und Radio-Fernseh-Techniker <!-- Gegründet von Curt Rint -->- Offizielles Mitteilungsblatt der Bundesfachgruppe Radio- und Fernsehtechnik |issn=0016-2825 |publisher={{ill|Dr. Alfred Hüthig Verlag GmbH|de|Hüthig GmbH}} |publication-place=Heidelberg, Germany |date=March 1983 |volume=38<!-- but has 37 on front side --> |issue=3 |pages=98–100 [98–99] |url=https://nvhrbiblio.nl/biblio/tijdschrift/Funktechnik/1983/FT_1983_Heft_03_OCR.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210425085549/https://nvhrbiblio.nl/biblio/tijdschrift/Funktechnik/1983/FT_1983_Heft_03_OCR.pdf |archive-date=2021-04-25 |quote-page=98 |quote=[…] UKW-FM mit High-Com […] Dafür wird dann High-Com-FM die Dynamik auf Werte zwischen 70&nbsp;dB und 80&nbsp;dB erweitern und gleichzeitig die Grenzempfindlichkeit für Stereobetrieb von heute etwa 20&nbsp;μV auf 6&nbsp;μV reduzieren […]. Außerdem wird die Nachbarkanal-Selektion im Bereich von ±100…200&nbsp;kHz im Mittel um etwa 10&nbsp;dB verbessert. […] Um einen möglichst guten kompatiblen Empfang - Empfang komprimierter Sendungen mit Geräten ohne Expander - zu garantieren, wird die Kompression bei High-Com-FM auf 10&nbsp;dB beschränkt. Es ist damit zu rechnen, daß umschaltbare High-Com-Expander entwickelt werden, die einerseits 10&nbsp;dB für UKW-High-Com-FM-Empfang und andererseits 20&nbsp;dB für Cassettenrecorder-Betrieb bieten […] Durch die Verbesserung der Nachbarkanal-Selektion werden auch Zwitscherstörungen, die heute noch relativ häufig auftreten, entscheidend reduziert. Auch der Rauschabstand starker Ortssender im Abstand von mehr als 300&nbsp;kHz zum Nutzsender - die Weitab-Selektion - wird um 10&nbsp;dB verbessert. […]}}</ref>
<ref name="Reuber_1983_2">{{cite magazine |title=Rundfunk für Europa - Pressekolloqium Rundfunktechnik während der IFA&nbsp;83 |language=de |department=Systeme und Konzepte |author-first=Claus |author-last=Reuber |magazine=Funk-Technik - Fachzeitschrift für Funk-Elektroniker und Radio-Fernseh-Techniker <!-- Gegründet von Curt Rint -->- Offizielles Mitteilungsblatt der Bundesfachgruppe Radio- und Fernsehtechnik |issn=0016-2825 |publisher={{ill|Dr. Alfred Hüthig Verlag GmbH|de|Hüthig GmbH}} |publication-place=Heidelberg, Germany |date=December 1983 |volume=38 |issue=18 |pages=494–497 [495] |url=https://nvhrbiblio.nl/biblio/tijdschrift/Funktechnik/1983/FT_1983_Heft_12_OCR.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210425020629/https://nvhrbiblio.nl/biblio/tijdschrift/Funktechnik/1983/FT_1983_Heft_12_OCR.pdf |archive-date=2021-04-25 |quote-page=495 |quote=[…] Bessere UKW-Qualität […] Deshalb bemühen sich die deutschen Rundfunkanstalten, die Empfangsqualität ihrer UKW-Sendungen durch ein Kompander-Verfahren zu verbessern, wobei allerdings im Gegensatz zu anderen Kompander-Methoden auf die Verträglichkeit (Kompatibilität) mit den vielen Millionen vorhandener Empfänger geachtet werden muß. Von allen bekannten Rauschminderungsverfahren kommen schon aus Kostengründen nur [[Dolby B|Dolby-B]] oder High-Com in Betracht. Die Kompatibilitätsforderung wird aber von beiden nur erfüllt, wenn sie den Besonderheiten der UKW-FM-Übertragung angepaßt werden. Mit Dolby-B werden bekanntlich nur höherfrequente Signalanteile kompandiert. Für Kompatibilität müßte das im Sender eingebaute Preemphase-Netzwerk von 50&nbsp;μs auf 25&nbsp;μs verändert werden. High-Com kompandiert frequenzunabhängig im gesamten Tonfrequenzbereich. Deshalb wird dies[es] System durch Frequenzgangfehler im Übertragungskanal nicht beeinträchtigt. Normalerweise erreicht High-Com einen Störabstandsgewinn um etwa 20&nbsp;dB, die Modifikation für FM-Rundfunk muß die Kompression und damit den Störabstandsgewinn auf 10&nbsp;dB reduzieren und die Regelzeitkonstanten verändern. So entstand in Zusammenarbeit zwischen Rundfunkanstalten und Telefunken die Variante High-Com-FM. Dieter Stahl wies als Technischer Direktor des [[Rundfunk im amerikanischen Sektor|Rias Berlin]] darauf hin, daß UKW-Übertragung mit High-Com zunächst einmal eine Erhöhung der Systemdynamik um etwa 10&nbsp;dB bei hohe[n] und mittleren Antennenspannungen ermöglicht. Bei niedrigen Antennenspannungen könnte[…] evtl. die Stereo-Mono-Schaltschwelle zu kleineren Spannungen verschoben werden. Damit würde sich eine Vergrößerung der Stereo-Versorgung ergeben. Bei sehr niedrigen Antennenspannungen, also sehr kleinen Signal/Stör-Abständen müßte sich der Expander im Empfänger automatisch abschalten, weil er sonst mehr Stör- als Nutzsignale erzeugt. Eine solche Abschaltautomatik ist auch für den Empfang nicht komprimierter Sendungen wichtig, denn nur-komprimierte Signale werden vom Hörer eher akzeptiert als nur-expandierte. Um alle Fragen in der Praxis zu klären, werden die Rundfunkanstalten mit High-Com-FM einen großen Feldversuch durchführen und erst dann entscheiden, ob dieses Kompander-System im UKW-Rundfunk eingeführt werden kann. […]}}</ref>
<ref name="FT_1984">{{cite magazine |title=Bundesweiter "High Com FM"-Hörfunktest |language=de |department=Technische Neuerungen |magazine=Funk-Technik - Fachzeitschrift für Funk-Elektroniker und Radio-Fernseh-Techniker <!-- Gegründet von Curt Rint -->- Offizielles Mitteilungsblatt der Bundesfachgruppe Radio- und Fernsehtechnik |issn=0016-2825 |publisher={{ill|Dr. Alfred Hüthig Verlag GmbH|de|Hüthig GmbH}} |publication-place=Heidelberg, Germany |date=March 1984 |volume=39 |issue=3 |pages=92–93 |url=https://docplayer.org/204544162-Fachzeitschrift-fuer-funk-esktroniker-und-radio-fernseh-teehmiker.html |access-date=2021-05-15 |url-status=live |archive-url=https://web.archive.org/web/20210515205746/https://docplayer.org/204544162-Fachzeitschrift-fuer-funk-esktroniker-und-radio-fernseh-teehmiker.html |archive-date=2021-05-15 |quote-pages=92–93 |quote=[…] Anfang Januar 1984 startete der Großversuch High&thinsp;Com FM in der gesamten Bundesrepublik. […] Nachdem erhebliche technische Schwierigkeiten überwunden sind, begann im Januar der Drei-Monats-Test für alle. […] Um mit der sprunghaft gestiegenen Tonqualität bei Speicherungs- und Aufzeichnungsverfahren Schritt zu halten, gehen die ARD-Rundfunkanstalten nun dem Übertragungsweg […] an den Kragen […] Um Störungen auf dieser Übertragungsstrecke zu vermindern, suchten die Experten der Sendeanstalten und des Instituts für Rundfunktechnik (IRT) nach einem geeigneten Kompandersystem. Solch ein System sieht vor, beim Sender mit Hilfe eines Kompressors die kleinen Pegel anzuheben, hohe Pegel dagegen nicht zu beeinflussen. Der Empfänger müßte nun einen Expander besitzen, der diese kleinen (und mittleren Pegel) mitsamt den auf der Übertragungsstrecke entstehenden Störungen wieder absenkt. Die Störungen würden damit also leiser oder im besten Fall unhörbar. Nun gibt es einen geeigneten Kompressor für die Sender, aber noch keine in die Empfänger eingebauten Expander. Entsprechende Geräte und Zusatzbausteine werden von der Industrie wohl erst nach dem erfolgreichen Großversuch serienmäßig zur Verfügung stehen. Der Kompressor muß also mindestens zwei Bedingungen erfüllen: 1. Er soll kompatibel sein, das heißt, die Hörer ohne Expander sollen keine Verschlechterung des Empfangs empfinden. 2. Wenn zu einem späteren Zeitpunkt die Empfänger Expander besitzen, soll die UKW-Empfangsqualität deutliche Verbesserungen zeigen. […] Aus den bekannten Kompandersystemen wählten die Fachleute das im Konsumbereich eingeführte High&thinsp;Com-System von [[AEG-Telefunken]] aus. Erste Versuche liefen allerdings unbefriedigend. Die senderseitige Kompression war zu stark und führte bei Empfängern ohne Expander zu nicht akzeptablen Verschlechterungen der Empfangsqualität. Also wurde das High&thinsp;Com-Verfahren so abgewandelt, daß der nicht expandierende Empfänger keine Qualitätseinbußen feststellen soll. Bisherige Tests mit Versuchspersonen veranlaßten einige Experten zu der Vermutung, daß die jetzt gewählten Systemeigenschaften von vielen Hörern sogar als Verbesserung empfunden werden könnten. Beim Autofahren sei die Lautstärkeanhebung leiser Tonstellen hilfreich für bessere Verständlichkeit und auch im Wohnzimmer könnte die Kompression durchaus als verstärkte Präsenz angenehm auffallen. […] Die für die UKW-Sender modifizierte High&thinsp;Com-Version enthält weder im Signal noch im Regelzweig Netzwerke zur Höhenanhebung bzw. -absenkung. Das heißt, der Kompander arbeitet frequenzunabhängig. Der Kompressionsgrad beträgt 10 dB. Laborversuche ergaben, daß ausgewählte Versuchspersonen nur bei zwei von 13 unterschiedlichen Programmbeispielen eine Qualitätsminderung wahrnehmen konnten und das nur im direkten Vergleich. Außerdem zeigten die Versuche, daß komprimiert gesendetes Quellenmaterial mindestens 55 dB Geräuschspannungsabstand haben sollte. Diese Forderung erfüllen viele moderne Tonträger (Studiostandard 2) sowie tel[…]com-kompandierte und digitale Aufzeichnungen. Psychoakustische Messungen haben ergeben, daß im fahrenden Kraftfahrzeug allein durch die senderseitige Kompression (ohne Expansion beim Empfänger) die Qualität des UKW-Empfangs verbessert wird, weil sich auch Programmteile mit ursprünglich geringem Pegel infolge der Lautstärkeanhebung besser vom Geräuschhintergrund abheben. Regelverzerrungen durch Übertragungsstörungen spielen offenbar ebenfalls im bewegten Auto durch die Umweltgeräusche keine Rolle. […]}}</ref>
<ref name="Simon_1984">{{cite magazine |title=Come ricevere le trasmissioni radio HIGH-COM-FM |language=it |author-first=Günter |author-last=Simon |magazine=Selezione di elettronica e microcomputer |department=Progetti |publisher={{ill|Jacopo Castelfranchi Editore|it|Jacopo Castelfranchi}} (JCE) |publication-place=Milano, Italy |date=September 1984 |issue=9 |id=ark:/13960/t0dv8cv6t<!-- |ia=Selezione_di_Tecniche_Elettroniche_1984_09 --> |pages=143–145 |url=https://archive.org/details/Selezione_di_Tecniche_Elettroniche_1984_09 |access-date=2021-04-25}} [https://archive.org/details/Selezione_di_Tecniche_Elettroniche_1984_09] (NB. Discusses the circuitry of a High&thinsp;Com&nbsp;FM decoder.)</ref>
<ref name="Shorter_1983">{{cite magazine |title=German radio show - The International Audio and Video Fair, also known as the German radio exhibition or Funkausstellung, continues to be held in Berlin. |author-first=Geoffrey |author-last=Shorter |magazine=[[Electronics & Wireless World]] |publisher=[[Business Press International Ltd]] |issn=0043-6062 |date=November 1983 |volume=89 |number=1574 |pages=73–75 [74–75] |url=https://worldradiohistory.com/UK/Wireless-World/80s/Wireless-World-1983-11.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210309022644/https://worldradiohistory.com/UK/Wireless-World/80s/Wireless-World-1983-11.pdf |archive-date=2021-03-09 |quote-page=75 |quote=[…] For two weeks around the time of the [[Funkausstellung]] [[Sender Freies Berlin]] was broadcasting its second programme on 92.4&nbsp;MHz encoded with a noise reduction system. That was [[Telefunken]]'s High&thinsp;Com, a wideband compander offering a noise reduction of about 20&nbsp;dB in cassette recorders (see [[#Shorter-1979|November 1979 report, page 49]]). But although Telefunken argue that this is better than the 15&nbsp;dB of Dolby C (A-weighted), it has proved difficult to market against Dolby, and not many licencees have adopted it in cassette machines. So for the last two or three years they have been experimenting with a version for f.m. radio to improve noise performance in fringe areas and increase service area. Because it is essential in this application that the encoded signal is received by conventional sets compatibly, the amount of noise reduction has needed to be reduced: starting with 9dB, they went up to 15 - with adverse effects - and then down through 12 to 10&nbsp;dB. Encoded broadcasts by [[Westdeutscher Rundfunk]] have not produced any complaints so far, so compatibility seems proven, say Telefunken. But before the scheme can be adopted nationwide there must be a consensus of the Länder broadcasting organisations and so further field tests are planned for next March. By the end of 1984 a new i.c. will be available which because it is 'single-ended' (decode-only) is simpler, smaller and cheaper than its predecessor, and can be used in car radio and portable cassette players as well. The resulting o.e.m. price reduction from DM10 to DM3 should help to establish High-Com-FM despite the advance of digital noise-free radio in Germany. The idea is also being discussed in France (Telefunken's parent company is Thomson Brandt) and in Austria. […]}}</ref>
<ref name="Kefauver_2001">{{cite book |title=The Audio Recording Handbook |author-first=Alan P. |author-last=Kefauver |chapter=Telcom C-4 Noise Reduction System |date=2001 |publisher=A-R Editions |edition=1st illustrated |isbn=0-89579462-4 |id={{ISBN|978-0-89579462-8}} |page=263 |url=https://books.google.com/books?id=bbNfr_bwUXwC&q=telcom |access-date=2021-04-30}}</ref>
<ref name="Schleef_2004">{{cite book |title=Akustisch-klangliche Optimierung digitaler Audio-Kompandersysteme für drahtlose Mikrofonanlagen |language=de |author-first=Daniel |author-last=Schleef |date=July 2004 |type=Diploma thesis |publisher=Erich-Thienhaus-Institut der [[Hochschule für Musik Detmold]] / [[Sennheiser electronic GmbH & Co. KG]] |url=http://virulus.de/audio/diplomarbeiten%20FH%20fuer%20Toningenieure%20und%20Tonmeister%20in%20Detmold/doc/DA%20Schleef%2002-09-2004.pdf |access-date=2020-07-03 |url-status=dead |archive-url=https://web.archive.org/web/20200703134549/http://virulus.de/audio/diplomarbeiten%20FH%20fuer%20Toningenieure%20und%20Tonmeister%20in%20Detmold/doc/DA%20Schleef%2002-09-2004.pdf |archive-date=2020-07-03}}</ref>
<ref name="Zander_2009">{{cite book |title=PC-gestützte Restaurierung von Audiosignalen |language=de |author-first=Horst |author-last=Zander |publisher={{ill|Schiele & Schön{{!}}Fachverlag Schiele & Schön|de|Schiele & Schön}} |date=2009 |edition=1 |isbn=3-79490778-7 |id={{ISBN|978-3-79490778-6}}<!-- Leave these ISBNs alone! --> |pages=177–178 |url=https://books.google.com/books?id=76rBuo9ptvcC&pg=PA177 |access-date=2021-05-07 |url-status=live |archive-url=https://web.archive.org/web/20220101214700/https://books.google.de/books?id=76rBuo9ptvcC&pg=PA177#v=onepage&q&f=false |archive-date=2022-01-01 |quote-page=177 |quote=[…] Für Kassettenaufnahmen, die bei der Aufnahme mit HighCom bearbeitet wurden und für die ein entsprechendes Wiedergabegerät nicht mehr zur Verfügung steht, wurde ein kleines Plug-in für [[Cool Edit Pro]] programmiert, dem Vorgänger von [[Adobe Audition]], das sich entsprechend HighCom nennt. […]}} [http://www.pyramidedata.dk/highcom.html]</ref>
<ref name="Hess_2018">{{cite web |title=An overview of optimizing signal-to-noise ratio primarily in analog audio tape recording |author-first=Richard L. |author-last=Hess |location=Aurora, Ontario, Canada |date=2018-10-17 |url=https://www.dhnrds.com/Noise%20reduction%20systems%20v9-p.pdf |access-date=2021-05-07 |url-status=live |archive-url=https://web.archive.org/web/20210508073315/https://www.dhnrds.com/Noise%20reduction%20systems%20v9-p.pdf |archive-date=2021-05-08}} (26 pages)</ref>
<ref name="Dyson-Hess_2019">{{cite web |title=DYSON-HESS Noise Reduction Decoder System |author-first1=John S. |author-last1=Dyson |author-first2=Richard L. |author-last2=Hess |date=2019-03-12 |version=0.7.1a |url=https://www.dhnrds.com/Dyson-Hess_NRDS_Manual_v0-7-1a-p.pdf |access-date=2021-05-07 |url-status=live |archive-url=https://web.archive.org/web/20210508072944/https://www.dhnrds.com/Dyson-Hess_NRDS_Manual_v0-7-1a-p.pdf |archive-date=2021-05-08}} (23 pages)</ref>
<ref name="RHW_1993">{{cite book |title=Regelwerk Hörfunk Wort - Richtlinien für die Formalbeschreibung, Inhaltserschließung und Feststellung der Dokumentationswürdigkeit von Wortproduktionen |language=de |chapter=1.4.03 Rauschunterdrückungsverfahren |author-first1=Brigitte |author-last1=Grimm |author-first2=Klemens |author-last2=Helmholz |author-first3=Sieglinde |author-last3=Osang |author-first4=Walter |author-last4=Roller |author-first5=Günther |author-last5=Welzel |author-first6=Hansjörg |author-last6=Xylander |author-first7=Ingolf |author-last7=Geiger |publisher=Arbeitsgruppe "Regelwerk Hörfunk Wort", [[ARD (broadcaster)|ARD]] |edition=expanded 2nd |publication-place=Stuttgart, Germany |date=August 1993 |orig-date=November 1987 |page=63 |url=http://rmd.dra.de/arc/ap/ard_hf_wort/rw/regelwerk_wort.pdf |access-date=2021-05-16 |url-status=live |archive-url=https://web.archive.org/web/20210430091953/http://rmd.dra.de/arc/ap/ard_hf_wort/rw/regelwerk_wort.pdf |archive-date=2021-04-30}}</ref>
<ref name="K_1983">{{cite magazine |title=HighCom-FM ist da - Weniger Rauschen beim Hörfunk: Experten halten HighCom für das beste Rauschunterdrückungssystem. Kommt es beim Rundfunk, können Sie fernere Sender besser hören. |language=de |trans-title= |author-first=H. |author-last=K. |department=Audio + Video |magazine={{ill|ELO (magazine){{!}}ELO|de|ELO (Zeitschrift)}} |issn=0341-4175 |publisher=[[Franzis-Verlag GmbH]] |issue=3 |date=March 1983 |pages=35–36 |quote-page=35 |quote=[…] Die Kompression ist jetzt allerdings nicht mehr 20&nbsp;dB, sondern 10&nbsp;dB. Und […] sie ist damit praktisch kompatibel. Denn der Dynamikverlust von 10&nbsp;dB stört in Empfängern ohne Expander praktisch nicht; im Gegenteil, im Autoradio, und nicht nur dort, wird die Sprachverständlichkeit erheblich besser. […] Daß aber auch HighCom-FM-komprimierte Musik im Normalgerät nicht als störend empfunden wird, haben die ARD-Anstalten längst bewiesen. Im vergangenen Herbst haben sie nämlich heimlich HighCom ausgestrahlt, und siehe da, es hat sich niemand beschwert. Einige meinten sogar: "Ihr seid ja besser als früher." […] In diesen Wochen wird man sich in einer internationalen Konferenz darüber klar werden, wo und wie man ein HighCom-Kennungssignal noch- natürlich unhörbar - mit überträgt. Und im Herbst (zur Funkausstellung) könnte es dann soweit sein: weniger Rauschen, weniger Zwitschern, mehr gut hörbare Programme auf UKW. […]}} (2 pages)</ref>
}}
== Further reading ==
* {{cite magazine |author-last1=Wermuth |author-first1=Jürgen |author-last2=Temmer |author-first2=Stephan F. |title=Dynamikerweiterung durch neuartigen Studio-Kompander |language=de |trans-title=Dynamic expansion through novel studio compander |magazine={{ill|Funkschau|de}} - Radio, Fernsehen, Elektroakustik, Elektronik |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |number=18 |volume=47 |date=1975-08-29 |pages=103–106?<!-- TBD: one source states 103–108 --> / 571– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol47num18/ -->}} (NB. This article mixes up the Dolby curve.)
* {{cite conference |author-last=Wermuth |author-first=Jürgen |title=Dynamik-Erweiterung durch neuartigen Studio-Kompander |conference=10. Tonmeistertagung |location=Köln, Germany |language=de |trans-title=Dynamic expansion through novel studio compander |orig-date=1975-11-19 |date=1975-11-22}}
* {{cite magazine |author-last1=Schröder |author-first1=Ernst F. |author-last2=Wermuth |author-first2=Jürgen |title=Ein neues Kompandersystem – Grundlagen und Einsatzmöglichkeiten |language=de |trans-title=A new compander system - Basics and applications |type=Speech at the FKTG Tagung |location=Freiburg, Germany |date=1976-10-05 |magazine={{ill|Fernseh- und Kinotechnik|de}} (FKT) |volume=30 |number=12 |pages=9–11}}
* {{cite magazine |author-first=Jürgen |author-last=Wermuth |title=Compander Increases Dynamic Range |magazine=db Magazine |date=June 1976}}
* {{cite journal |author-last1=Dickopp |author-first1=Gerhard |author-last2=Schröder |author-first2=Ernst F. |title=Der Telefunken-Kompander |language=de |trans-title=The Telefunken compander |journal=Rundfunktechnische Mitteilungen (RTM) |volume=22 |date=1978 |issue=2 |pages=17–28 / 63–74}}
* {{cite magazine |author-last1=Dickopp |author-first1=Gerhard |author-last2=Schröder |author-first2=Ernst F. |title=Meßverfahren für Kompander |language=de |trans-title=Measurement technologies for companders |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |volume=50 |date=1978-08-11 |issue=17 |pages=29–32 <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol50num17/ -->}}
* {{citation |title=Circuit system for the generation of a direct control voltage which is dependent on an alternating voltage |author-last1=Schröder |author-first1=Ernst F. |author-last2=Wermuth |author-first2=Jürgen |id=DE2830784, US4321482 |date=1978-07-13 |url=https://patents.google.com/patent/US4321482}} [https://patents.google.com/patent/DE2830784A1]
* {{citation |title=Schaltung zur wahlweisen automatischen Dynamikkompression oder -expansion |author-last=Scholz |author-first=Werner |id=DE2856045 |date=1978-12-23 |url=https://patents.google.com/patent/DE2856045A1}} [https://patents.google.com/patent/DE2856045C2]
* {{cite journal |author-last1=Dickopp |author-first1=Gerhard |author-last2=Schröder |author-first2=Ernst F. |title=HIGH&thinsp;COM - Ein Kompander von Telefunken |language=de |publisher=[[Telefunken]] |journal=Telefunken Firmenschrift |date=April 1979}}
* {{citation |title=Schaltung zur wahlweisen automatischen Dynamikkompression oder -expansion |author-last=Schröder |author-first=Ernst F. |id=DE2919280 |date=1979-05-12 |url=https://patents.google.com/patent/DE2919280A1}} [https://patents.google.com/patent/DE2919280C2]
* {{anchor|Shorter-1979}}{{cite magazine |title=Europe responds to Japanese video - Internationale Funkausstellung, Berlin 24.8-2.9 |author-first=Geoffrey |author-last=Shorter |magazine=[[wireless world]] - Electronics / Television / Radio / Audio |type=report |publisher=[[IPC Business Press Ltd]] |issn=0043-6062 |date=November 1979 |volume=85 |number=1527 |pages=46–50 [49] |url=https://worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1979-11.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210309013408/https://worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1979-11.pdf |archive-date=2021-03-09}}
* {{cite book |title=Telefunken Report '79–80 - HiFi-Anlagen, Radio-Rekorder, Heimradios |chapter=Das neue Rausch- und Störunterdrückungssystem von Telefunken. Ein Meilenstein in der High-Fidelity. |language=de |type=Product catalog |date=1979 |publisher=[[Telefunken]] |id=E-Nr. 370381235 |page=28 |url=http://www.hifi-archiv.info/Telefunken/1979/telefunken79-28.jpg |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20200702113130/http://www.hifi-archiv.info/Telefunken/1979/telefunken79-28.jpg |archive-date=2020-07-02}}
* {{cite magazine |title=High-Com für Profis |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=1980-07-04 |issue=14 |volume=52 |pages=81–<!-- TBD: some sources cite this as "8–" --> <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol52num14/ -->}}
* {{cite magazine |author-first=Bernd |author-last=Wiedenroth |title=High-Com - Überblick und Entwicklungsstand |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=1980-08-15 |issue=17 |volume=52 |pages=67–71 <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol52num17/ -->}}
* {{cite conference |author-last=Schröder |author-first=Ernst F. |title=Dynamikkompander - Stand und Ausblick |language=de |location=Nachrichtentechnisches Kolloqium im Fachbereich Elektrotechnik der Universität Duisburg |date=Summer 1980}}
* {{cite magazine |title=Nakamichi High-Com II Noise-Reduction System |author-first=Howard A. |author-last=Roberson |volume= |issue=9 |date=<!-- September? -->1980 |magazine=[[Audio (magazine)|Audio]]<!-- English magazine --> |language=en |series=Equipment profiles |pages=62–66}}
* {{cite journal |author-last=Schröder |author-first=Ernst F. |title=A New Integrated Audio Compansion System |journal=Proceedings of the Forth European Conference on Electronics (Eurocon '80) |location=Stuttgart, Germany |date=1980 |pages=612–614}}
* {{cite journal |author-last1=Höppner |author-first1=Dietrich |author-last2=Schröder |author-first2=Ernst F. |title=HIGH&thinsp;COM - ein Kompander zur breitbandigen Geräuschunterdrückung |language=de |journal=Technische Rundschau |number=41 |date=October 1980}}
* {{cite magazine |title=Nakamichi High-Com II Noise Reduction System |magazine=Modern Recording & Music |issn=0361-0004 |publisher=Cowan Publishing Corp. |publication-place=Port Washington, New York, USA |number=1 |volume=6 |date=October 1980 |page=75 |url=https://worldradiohistory.com/hd2/IDX-Audio/Archive-Modern-Recording-IDX/IDX/80s/Modern-Recording-1980-10-OCR-Page-0075.pdf |access-date=2021-05-17 |url-status=live |archive-url=https://web.archive.org/web/20210516093754/https://worldradiohistory.com/hd2/IDX-Audio/Archive-Modern-Recording-IDX/IDX/80s/Modern-Recording-1980-10-OCR-Page-0075.pdf |archive-date=2021-05-16}} [<!-- https://worldradiohistory.com/Archive-All-Audio/Archive-Modern-Recording/80s/Modern-Recording-1980-10.pdf -->https://web.archive.org/web/20210310024619/https://worldradiohistory.com/Archive-All-Audio/Archive-Modern-Recording/80s/Modern-Recording-1980-10.pdf]
* {{cite book |title=Telefunken High Fidelity Programm '80–81 |chapter=Das neue Rausch- und Störunterdrückungssystem von Telefunken. Ein Meilenstein in der High-Fidelity. |language=de |type=Product catalog |date=1980 |publisher=[[Telefunken]]  |id=E-Nr. 318391519 |page=4 |url=http://www.hifi-archiv.info/Telefunken/1980-2/telefunken80-04.jpg |access-date=2020-07-02 |url-status=live |archive-url=https://web.archive.org/web/20200702150406/http://www.hifi-archiv.info/Telefunken/1980-2/telefunken80-04.jpg |archive-date=2020-07-02}}
* {{cite magazine |title=High-Com Professional (TTS NR-2) |language=de |magazine={{ill|Studio Magazin{{!}}Studio|de|Studio Magazin}} |department=StudioMix |publisher=Studio Presse Verlags GmbH |date=January 1981 |number=35? |pages=20?–21? [5?] |url=https://view.publitas.com/34439/466221/pages/725c7a5c59799bc9acb20dc787b8b5d494ecdb6d-at2000.jpg |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210425033701/https://view.publitas.com/34439/466221/pages/725c7a5c59799bc9acb20dc787b8b5d494ecdb6d-at2000.jpg |archive-date=2021-04-25}}
* {{cite magazine |title=Kompandersystem; Dolby C kontra High Com |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=1981-04-03 |issue=7 |volume=53 |pages=76– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol53num7/ -->}}
* {{cite journal |title=HIGH COM<!-- don't replace the thin-space! --> |journal=Audio Engineering |number=3 |volume=1981 |date=1981 |pages=30–35}}
* {{cite conference |author-last=Schröder |author-first=Ernst F. |title=Kompatibilität von Konsumgeräte-Kompandern zur Geräuschunterdrückung |language=de |conference=1. Tonmeistertagung |location=Munich, Germany |date=1981 |type=Report |pages=295–301}}
* {{cite magazine |title=Einbau eines Kompanders - Verstärker mit High-Com |language=de |author-first=Werner |author-last=Ratzki |magazine={{ill|Funkschau|de}} - Elektronik in Audio und Video, Kommunikation und Meßtechnik |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=1982-08-06 |issue=16 |volume=54 |pages=57–59 |url=http://www.theimann.com/Analog/Misc_Tech/HighCom/index.html |access-date=2020-07-01 |url-status=live |archive-url=https://web.archive.org/web/20200701122920/http://www.theimann.com/Analog/Misc_Tech/HighCom/index.html |archive-date=2020-07-01}} [https://web.archive.org/web/20200702150756/https://www.z80cpu.eu/mirrors/oldcomputers.dyndns.org/public/pub/manuals/HiFi-Technik/Sonstiges/alte%20artikel/funkschau-1982-16-einbau-eines-kompanders.zip<!-- https://www.z80cpu.eu/mirrors/oldcomputers.dyndns.org/public/pub/manuals/HiFi-Technik/Sonstiges/alte%20artikel/funkschau-1982-16-einbau-eines-kompanders.zip -->]<!-- https://www.radiomuseum.org/lf/p/funkschau/vol54num16/ --> (3 pages)
* {{cite magazine |title=Rauschkiller: Dolby- und High-Com-Rauschminderung - Teil 1 |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=February 1983<!-- first issue in February --> |issue=3 |volume=55 |id=Part 1 |pages=76– |postscript=none <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol55num3/ -->}}, {{cite magazine |title=Rauschkiller: Dolby- und High-Com-Rauschminderung - Teil 2 |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=February 1983<!-- second issue in February --> |issue=4 |volume=55 |id=Part 2 |pages=82– |postscript=none <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol55num4/ -->}}, {{cite magazine |title=Rauschkiller: Dolby- und High-Com-Rauschminderung - Teil 3 |language=de |magazine={{ill|Funkschau|de}} |issn=0016-2841 |publisher=[[Franzis-Verlag GmbH]] |publication-place=Munich, Germany |date=March 1983<!-- first issue in March --> |issue=5 |volume=55 |id=Part 3 |pages=80– <!-- |url=https://www.radiomuseum.org/lf/p/funkschau/vol55num5/ -->}}
* {{cite magazine |title=Riduzione del rumore nei registratori - part I |language=it |author-first=Günter |author-last=Simon |department=Alta fedelta' |magazine=Selezione di Tecniche Elettroniche |publisher={{ill|Jacopo Castelfranchi Editore|it|Jacopo Castelfranchi}} (JCE) |publication-place=Milano, Italy |date=July–August 1983 |issue=7/8 |id=ark:/13960/t23c2wm6j <!-- |ia=Selezione_di_Tecniche_Elettroniche_1983_07_08 --> |pages=59–62 |url=http://www.introni.it/pdf/Selezione%20di%20Tecniche%20Elettroniche%201983_07_08.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210425113810/http://www.introni.it/pdf/Selezione%20di%20Tecniche%20Elettroniche%201983_07_08.pdf |archive-date=2021-04-25 |postscript=none}} [https://archive.org/details/Selezione_di_Tecniche_Elettroniche_1983_07_08], {{cite magazine |title=Riduzione del rumore nei registratori - part II |language=it |author-first=Günter |author-last=Simon |department=Alta fedelta' |magazine=Selezione di Tecniche Elettroniche |publisher={{ill|Jacopo Castelfranchi Editore|it|Jacopo Castelfranchi}} (JCE) |publication-place=Milano, Italy |date=September 1983 |issue=9 |id=ark:/13960/t8rc3ws0t <!-- |ia=Selezione_di_Tecniche_Elettroniche_1983_09 --> |pages=90–92, 95–96 |url=http://www.introni.it/pdf/Selezione%20di%20Tecniche%20Elettroniche%201983_09.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210425112543/http://www.introni.it/pdf/Selezione%20di%20Tecniche%20Elettroniche%201983_09.pdf |archive-date=2021-04-25 |postscript=none}} [https://archive.org/details/Selezione_di_Tecniche_Elettroniche_1983_09], {{cite magazine |title=Riduzione del rumore nei registratori - part III |language=it |author-first=Günter |author-last=Simon |department=Alta fedelta' |magazine=Selezione di Tecniche Elettroniche |publisher={{ill|Jacopo Castelfranchi Editore|it|Jacopo Castelfranchi}} (JCE) |publication-place=Milano, Italy |date=October 1983 |issue=10 |id=ark:/13960/t8kd8r97z <!-- |ia=Selezione_di_Tecniche_Elettroniche_1983_10 --> |pages=92–96 |url=http://www.introni.it/pdf/Selezione%20di%20Tecniche%20Elettroniche%201983_10.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20210425112349/http://www.introni.it/pdf/Selezione%20di%20Tecniche%20Elettroniche%201983_10.pdf |archive-date=2021-04-25}} [https://archive.org/details/Selezione_di_Tecniche_Elettroniche_1983_10][https://archive.org/download/Selezione_di_Tecniche_Elettroniche_1983_10/Selezione_di_Tecniche_Elettroniche_1983_10_text.pdf]
* {{cite book |title=Telefunken U401BR |url=http://www.eserviceinfo.com/download.php?downloadstart=1&fileid=60740 |access-date=2017-11-14 |url-status=live |archive-url=https://web.archive.org/web/20171114213813/http://www.eserviceinfo.com/download.php?downloadstart=1&fileid=60740 |archive-date=2017-11-14}} [https://web.archive.org/web/20171112123545/http://www.eserviceinfo.com/preview.php?fileid=60740&file=HighCom__ic_U401BR__Telefunken.gif]
* {{cite magazine |author-first=Wolfgang |author-last=Schneider |title=telcom c4 noise reduction system |magazine=Studio Sound and Broadcast Engineering |issn=0133-5944 |publisher=Link House Publications PLC |publication-place=Croydon, UK |date=February 1985 |volume=27 |number=2 |pages=46–48 |url=https://worldradiohistory.com/Archive-All-Audio/Archive-Studio-Sound/80s/Studio-Sound-1985-02.pdf |access-date=2021-05-16 |url-status=live |archive-url=https://web.archive.org/web/20210310053049/https://worldradiohistory.com/Archive-All-Audio/Archive-Studio-Sound/80s/Studio-Sound-1985-02.pdf |archive-date=2021-03-10}} (3 pages)
* {{cite magazine |author-first=Keith |author-last=Spencer-Allen |title=Practical telcom c4 |magazine=Studio Sound and Broadcast Engineering |issn=0133-5944 |publisher=Link House Publications PLC |publication-place=Croydon, UK |date=April 1986 |volume=28 |number=4 |pages=56–58 |url=https://worldradiohistory.com/Archive-All-Audio/Archive-Studio-Sound/80s/Studio-Sound-1986-04.pdf |access-date=2021-05-16 |url-status=live |archive-url=https://web.archive.org/web/20210310052831/https://worldradiohistory.com/Archive-All-Audio/Archive-Studio-Sound/80s/Studio-Sound-1986-04.pdf |archive-date=2021-03-10}} (3 pages)
* {{cite book |title="HIGH-COM" User Manual / Service Manual (HIGH-COM code+decode 9.5") |publisher=D&R Electronica B.V. |location=Weesp, Netherlands |date=1986-11-05 |orig-date=1985-04-04, 1984 |url=http://d-r.nl/assets/highcom-manual.pdf |access-date=2021-04-25 |url-status=live |archive-url=https://web.archive.org/web/20170223213848/http://d-r.nl/assets/highcom-manual.pdf |archive-date=2017-02-23}} [https://web.archive.org/web/20170223181747/http://d-r.nl/assets/high-com-noise-reduction.jpg] (3+13 pages)
* {{cite book |author-last=Schröder |author-first=Ernst F. |title=Beitrag zur Analyse und zur Dimensionierung von Kompandern anhand einer einheitlichen Beschreibungsweise |language=de |trans-title=Contribution to Analysis and Dimensioning of Companders by utilizing a Unified Description |type=PhD thesis |date=1989-07-07 |url=http://www.ernstschroeder.de/Diss_EFSchroeder_1989.pdf |access-date=2017-11-15 |url-status=live |archive-url=https://web.archive.org/web/20200529144034/https://www.ernstschroeder.de/Diss_EFSchroeder_1989.pdf |archive-date=2020-05-29}}
* {{cite book |author-first=Thomas |author-last=Görne |editor-first=Ulrich |editor-last=Schmidt |title=Tontechnik |language=de |trans-title=Audio technology |edition=1 |publisher=[[Carl Hanser]] |location=Leipzig, Germany |date=2006 |isbn=3-446-40198-9}}
==External links==
* https://www.radiomuseum.org/r/thomsen_el_high_com_rauschunterdrueckung_hobby_com.html<!-- https://web.archive.org/web/20171105134540/https://www.radiomuseum.org/r/thomsen_el_high_com_rauschunterdrueckung_hobby_com.html -->
* http://www.tonbandhobby.de/high-com.htm#aiwa<!-- https://web.archive.org/web/20171105134548/http://www.tonbandhobby.de/high-com.htm -->
* http://haisen.cool.coocan.jp/garakuta/AV/audio/NR.htm<!-- https://web.archive.org/web/20171105134916/http://haisen.cool.coocan.jp/garakuta/AV/audio/NR.htm -->
* https://www.ernstschroeder.de/highcom.htm
[[Category:Magnetic tape noise reduction systems]]
<!-- [[Category:Radio noise reduction systems]] applies only to High Com FM -->
<!-- [[Category:Vinyl disc noise reduction systems]] applies only to High-Com II -->