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Zweikanalton ("two-channel sound") or A2 Stereo, is an analog
television
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
sound transmission system used in
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
,
Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
,
Australia,
Switzerland,
Netherlands
)
, anthem = ( en, "William of Nassau")
, image_map =
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of the Netherlands
, established_title = Before independence
, established_date = Spanish Netherl ...
and some other countries that use or used
PAL
Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...
-B or PAL-G.
TV3 Malaysia formerly used Zweikanalton on its UHF analogue transmission frequency (Channel 29), while
NICAM
Near Instantaneous Companded Audio Multiplex (NICAM) is an early form of lossy compression for digital audio. It was originally developed in the early 1970s for point-to-point links within broadcasting networks.Croll, M.G., Osborne, D.W. and Spi ...
was instead used on its VHF analogue transmission frequency (Channel 12).
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korean Peninsula and sharing a land border with North Korea. Its western border is formed by the Yellow Sea, while its eas ...
also formerly utilised a modified version of Zweikanalton for its
NTSC
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
analogue television system until 31 December 2012. It relies on two separate
FM carriers.
This offers a relatively high separation between the channels (compared to a
subcarrier-based
multiplexing system) and can thus be used for
bilingual broadcasts as well as
stereo. Unlike the competing NICAM standard, Zweikanalton is an
analog
Analog or analogue may refer to:
Computing and electronics
* Analog signal, in which information is encoded in a continuous variable
** Analog device, an apparatus that operates on analog signals
*** Analog electronics, circuits which use analog ...
system.
How it works
A 2nd FM sound carrier containing the right channel for stereo is transmitted at a frequency 242 kHz higher than the existing
mono
Mono may refer to:
Common meanings
* Infectious mononucleosis, "the kissing disease"
* Monaural, monophonic sound reproduction, often shortened to mono
* Mono-, a numerical prefix representing anything single
Music Performers
* Mono (Japanese b ...
FM sound carrier, and channel mixing is used in the receiver to derive the left channel.
The second sound carrier also contains a 54.6875 kHz pilot tone to indicate whether the transmission is stereo or bilingual.
The pilot tone is 50% amplitude-modulated with 117.5 Hz for stereo or 274.1 Hz for bilingual.
:a.The second sound carrier frequency of DK systems varies from country, and sometimes manufacturers divide them into DK1/DK2/DK3 systems.
:b.The video bandwidth is reduced.
Zweikanalton can be adapted to any existing analogue television system, and modern PAL or SECAM television receivers generally include a sound detector IC that can decode both Zweikanalton and NICAM.
Zweikanalton can carry either a completely separate audio program, or can be used for stereo sound transmission. In the latter case, the first FM carrier carries (L+R) for compatibility, while the second carrier carries R (not L-R.) After combining the two channels, this method improves the
signal-to-noise ratio by reducing the correlated noise between the channels.
The frequencies are chosen such that they cause minimal interference to the picture. The difference between the two sound carriers is 15.5 times the line frequency (15.5 x 15625 Hz = 242187.5 Hz) which, being an odd multiple of half line frequency, reduces the visibility of
intermodulation
Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency comp ...
products between the two carriers. The pilot tone frequency is 3.5 times line frequency (54687.5 Hz). The modulated tone frequency is 117.50 Hz for stereo transmission and 274.1 Hz for bilingual transmission. Absence of this tone is interpreted as a monaural transmission.
System M variant
There is a modified version of Zweikanalton used in
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korean Peninsula and sharing a land border with North Korea. Its western border is formed by the Yellow Sea, while its eas ...
, compatible with the NTSC
System M standard of TV transmission. In this case the second FM carrier is 14.25 times the line frequency, or about 224 kHz, above the first carrier; pre-emphasis is 75 microseconds; the stereo pilot tone frequency is 149.9 Hz; the bilingual pilot tone frequency is 276 Hz; and the second channel carries L-R (not R).
History
Zweikanalton was developed by the
Institut für Rundfunktechnik
The Institut für Rundfunktechnik GmbH (IRT) (''Institute for Broadcasting Technology Ltd.'') was a research centre of German broadcasters ( ARD / ZDF / DLR), Austria's broadcaster (ORF) and the Swiss public broadcaster ( SRG / SSR). It was respo ...
(IRT) in Munich during the 1970s, and was first introduced on the German national television channel
ZDF
ZDF (, short for Zweites Deutsches Fernsehen; ; "Second German Television") is a German public-service television broadcaster based in Mainz, Rhineland-Palatinate. It is run as an independent nonprofit institution, which was founded by all fe ...
on 13 September 1981. The German public broadcaster
ARD subsequently introduced Zweikanalton on its
Das Erste channel on 29 August 1985 in honour of the 1985 edition of the
Internationale Funkausstellung Berlin
The IFA ( ) or Internationale Funkausstellung Berlin (International radio exhibition Berlin, a.k.a. 'Berlin Radio Show') is one of the oldest industrial exhibitions in Germany. Between 1924 and 1939 it was an annual event, but from 1950 it was ...
(IFA). The (then)-West Germany thus became the first country in Europe to use
multiplexed sound on its television channels.
As a result of the analogue television switch-off in most countries which used Zweikanalton during 2006–2019, Zweikanalton is now considered obsolete and has been replaced with
MPEG-2 and/or
MPEG-4 for countries that have converted to DVB-T/DVB-T2 (Germany, Austria, Australia, Switzerland, Netherlands, Malaysia), and
Dolby Digital AC-3 for countries that have converted to ATSC (South Korea).
Other names
Zweikanalton is known by a variety of names worldwide. Most commonly used names are ''Zweiton'', ''German Stereo'', ''A2 Stereo'', ''West German Stereo'' and ''IGR Stereo''.
See also
*
Multichannel television sound
Multichannel Television Sound, better known as MTS, is the method of encoding three additional audio channels into an analog NTSC-format audio carrier. It was developed by the Broadcast Television Systems Committee, an industry group, and somet ...
(3 additional audio channels in an NTSC-format audio carrier.)
*
NICAM
Near Instantaneous Companded Audio Multiplex (NICAM) is an early form of lossy compression for digital audio. It was originally developed in the early 1970s for point-to-point links within broadcasting networks.Croll, M.G., Osborne, D.W. and Spi ...
*
EIAJ MTS
EIAJ MTS is a multichannel television sound standard created by the EIAJ.
Bilingual and stereo sound television programs started being broadcast in Japan in October 1978 using a " FM-FM" system originally developed by NHK Technical Research La ...
Notes and references
{{Analogue TV transmitter topics
Broadcast engineering
Television technology