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 advertising, ...

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 betwee ...

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 Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

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 Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

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 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 broa ...

-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. It is believed that multilingual speakers outnumber monolingual speakers in the world's population. More than half of all ...

broadcasts as well as

stereo Stereophonic sound, or more commonly 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 configuration ...

. Unlike the competing NICAM standard, Zweikanalton is an 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 (Japanes ...

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 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 the noise power, often expressed in de ...

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

, compatible with the NTSC

System M A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expresse ...

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 (IRT) in Munich during the 1970s, and was first introduced on the German national television channel ZDF 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 association of public broadcasting corporations in Germany. ''Das Erste'' is jointly operated by the nine regional public broadcasting corporations that are member ...

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 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 t ...

for countries that have converted to DVB-T/DVB-T2 (Germany, Austria, Australia, Switzerland, Netherlands, Malaysia), and

Dolby Digital Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995, the audio compression is loss ...

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''.

Notes and references

{{Analogue TV transmitter topics Broadcast engineering Television technology

How it works

System M variant

History

Other names

See also

Notes and references