Zweikanalton ("two-channel sound"), or A2 Stereo, is an analog

television Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, ...

sound transmission system used in

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Croatia Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...

Serbia , image_flag = Flag of Serbia.svg , national_motto = , image_coat = Coat of arms of Serbia.svg , national_anthem = () , image_map = , map_caption = Location of Serbia (gree ...

and some other countries that use or used CCIR systems.

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

utilized a modified version of Zweikanalton for the

NTSC NTSC (from National Television System Committee) is the first American standard for analog television, published and adopted in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170. In 1953, a second ...

analog television standard. It relies on two separate FM carriers. This offers a relatively high separation between the channels (compared to a

subcarrier A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio bro ...

-based

multiplexing In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource� ...

system) and can thus be used for

bilingual Multilingualism is the use of more than one language, either by an individual speaker or by a group of speakers. When the languages are just two, it is usually called bilingualism. It is believed that multilingual speakers outnumber monolin ...

broadcasts as well as

stereo Stereophonic sound, commonly shortened to stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configurat ...

. Unlike the competing NICAM standard, Zweikanalton is an analog system. 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.

Technical details

A 2nd FM sound carrier containing a second sound channel is transmitted at a frequency 242 kHz higher than the default FM sound carrier, and contains a 54.6875 kHz pilot tone to indicate whether the broadcast is mono, stereo or bilingual. This pilot tone is 50% amplitude-modulated with 117.5 Hz for stereo or 274.1 Hz for bilingual. The absence of this carrier indicates normal mono sound. The Zweikanalton FM carrier has to be 20 dB weaker than video carrier and 7 dB weaker than default FM sound carrier, to avoid video interference issues. 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 Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to noise power, often expressed in deci ...

by reducing the correlated noise between the channels. Carrier frequencies are chosen so 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 Signal (electrical engineering), signals containing two or more different frequencies, caused by non-linear, nonlinearities or time variance in a system. ...

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. :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.

System M variant

There is a modified version of Zweikanalton used in South Korea, 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 (IRT) in Munich during the 1970s, and was first introduced on the German national television channel

ZDF ZDF (), short for (; ), is a German public-service television broadcaster based in Mainz, Rhineland-Palatinate. Launched on 1 April 1963, it is run as an independent nonprofit institution, and was founded by all federal states of Germany ( ...

on 13 September 1981. The German public broadcaster ARD subsequently introduced Zweikanalton on its

Das Erste Das Erste (; "The First") is the flagship national television channel of the ARD (broadcaster), ARD association of public broadcasting corporations in Germany. ''Das Erste'' is jointly operated by the ARD (broadcaster)#Institutions and member org ...

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 w ...

(IFA). West Germany thus became the first country in Europe to use multiplexed sound on its television channels. In

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

, TV3 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). In

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

, the first TV station to use Zweikanalton was SCTV, which utilized from its start of broadcasting in 1990. Later, Zweikanalton was abandoned by national networks in favor of

but at least there was one local television station that still used Zweikanalton. In

Serbia , image_flag = Flag of Serbia.svg , national_motto = , image_coat = Coat of arms of Serbia.svg , national_anthem = () , image_map = , map_caption = Location of Serbia (gree ...

NTV Studio B used Zweikanalton from its first start of broadcasting in March 1990 and Reopening on November 16th 1990 on its all channels (UHF 32,40,49,51 and 53) for stereo transmission. In 1994 it stopped to use Zweikanalton because of technical video interference issues. In 2000s this technology was successfully used by Fox televizija, RTS and many cable operators also for stereo transmission only. In

Zweikanalton was used by HRT from 1990-s on all three channels (HRT1, HRT2 and HRT3) also for stereo transmission only. As a result of the analogue television switch-off in most countries which used Zweikanalton, Zweikanalton is now considered obsolete and has been replaced with

MPEG-2 MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods ...

and/or

MPEG-4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related ...

for countries that have converted to

DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Fe ...

DVB-T2 DVB-T2 is an abbreviation for "Digital Video Broadcasting – Second Generation Terrestrial"; it is the extension of the television standard DVB-T, issued by the consortium DVB, devised for the broadcast transmission of digital terrestrial telev ...

(Europe and Asia-Pacific), and

Dolby Digital Dolby Digital, originally synonymous with Dolby AC-3 (see below), is the name for a family of audio compression technologies developed by Dolby Laboratories. Called Dolby Stereo Digital until 1995, it is lossy compression (except for Dolby Tr ...

AC-3 on ATSC in South Korea.

Other names

Zweikanalton is known by a variety of names worldwide. Most commonly used names are ''Zweiton'', ''German Stereo'', ''A2 Stereo'', ''Dual FM Stereo'', ''West German Stereo'', ''Zwei Träger System'' and ''IGR Stereo''.

Notes and references

{{Analogue TV transmitter topics Broadcast engineering Television technology

Technical details

System M variant

History

Other names

See also

Notes and references