Zweikanalton

The two-channel, two-tone or A2 method is an analog technique for sound transmission in analogue terrestrial television, in which two independent audio channels to be transmitted. The two channels can be either 2-channel stereophonic, for the transmission of texts in different languages ​​(such as original and the dubbed version of a foreign film ), or for the transmission of standard version for normal vision and hearing film version for the Blind and Visually Impaired ( Two -channel sound) are used. If two versions are transmitted, only mono operation is possible because only two audio channels are available.

  • 4.1 NICAM
  • 4.2 MTS
  • 5.1 Analogue Satellite TV
  • 5.2 Digital TV 5.2.1 DVB- T

Technology

In the analogue terrestrial or cable transmission of television stations in German-speaking ( TV standard PAL -B / G) are frequency modulated video carrier to the two recordings at a distance of 5.5 MHz and 5.7421875 MHz. The subcarrier at 5.74 MHz ... is 20 dB weaker than the picture carrier or 7 dB weaker than the main sound carrier at 5.5 MHz to cause any interference in the picture. For the same reason he is at a distance of 15.5 times the line frequency from the main beam, so is midway between two harmonics.

Compatibility

For stereo transmission the main carrier with the sum signal (L R) and the sub-carrier is modulated with the signal 2R; Mono televisions that evaluate only the main beam, so a mixture of both channels play from, stereo TVs can by difference reconstruct the left channel. In the case of two-channel transmission, the main channel from the main language or the normal version, the secondary channel is modulated with the second language or the audio film version, therefore mono television units play back only the main language. For identification and distinction of the method, a pilot signal of 54.6875 kHz ( 3.5 times the line frequency of 15.625 kHz) in an auxiliary channel ( 5.74 MHz) is amplitude-modulated at 274 Hz ( two-channel ) and 117 Hz (stereo ) and transferred.

Reconstruction of the two-channel transmission:

Variant for standard M

A variant of the two-channel method is used in South Korea for the local standard M with NTSC color. The main carrier is NTSC-M at 4.5 MHz, the subcarrier on the 14.25 times the line frequency, thus at about 4,724 MHz at a pre -emphasis of 75 microseconds. The pilot tones for the identification of transmission lie at 149.9 Hz for stereo and 276 Hz, for bilingual programs. Another difference from the B / G variant is that the subcarrier in the stereo mode, the difference LR modulated ( instead of R as in the B / G method). South Korea, thus deviating from the usual for the standard M multi-channel method MTS.

Dissemination

The bilingual and A2 method is used in the B / G variant except in Germany but also in Austria, Switzerland and the Netherlands in analog terrestrial and cable transmission, as well as in South Korea in the M variant.

History

The German bilingual method was developed by the IRT. It was introduced by ZDF on 13 September 1981. The Federal Republic was the first country in Europe with multi-channel sound on TV. The expansion of the ZDF broadcasting network was then gradually, why not the entire transmission area was initially received Mehrkanaltonsendungen. In order to make the new technology to the audience tasty, was broadcast daily 2:00 p.m. to 16:00 clock a 30-minute infomercial. The first led the bilingual on August 29, 1985 at the IFA 1985.

Other standards for multichannel sound on terrestrial television

NICAM

In most other countries with European standards on Zeilen/25 625 frames per second, the digital method NICAM 728 is widely used for stereo and dual-channel audio transmission in analog TV. It was developed in the UK by the BBC. When NICAM analog audio is broadcast in mono parallel, for compatibility with mono receivers.

MTS

A third variant is the widespread particularly in conjunction with the standard M NTSC MTS method.

Multi-channel sound in other distribution channels

The bilingual method, as well as NICAM and MTS only applied to analogue terrestrial TV transmission, as well as analog cable channels.

Analog satellite television

In the analogue satellite transmission were due to the much larger frequency range more than two audio subcarriers per TV channel available, which could be selected by programming the receiver. Thus, it was also possible to transfer movies in the original in stereophonic or there have been several different languages ​​recorded two - or multi-channel. The other subcarriers beyond the second were often used for radio programs. Examples of these techniques was to one of the transmitters First, the analogy to the first two recordings at 7.02 MHz and 7.20 MHz above wore their own stereo and on ASTRA in addition to the sub-carriers 7.38 MHz and 7.56 MHz to radio station SWR3 mitsendete in stereo. When the transmitters ARTE and Euro sport the same sound has been sent with foreign commentators on the respective recordings.

Digital television

In digital television and stereo and bilingual is implemented digitally, 2005, the MPEG- 2 method was almost always used either with the sound in MPEG-1 Layer 2 or Dolby Digital system, which it multi-channel content to DD7.1 permits. But there are also DVB -S channels that radiate both types ( MPEG Audio, Dolby Digital) in parallel.

DVB- T

In DVB- T ( The First and BR ), there are problems with the dual channel. To old recipients with the opportunity to receive dual channel, sends the first non- compliant with the DVB- T specifications. The sound is sent to the left or right stereo channel. Thus, it is not possible to select the channel with modern DVB- T receivers, expect a two-channel coding.

Analogsignal Amplitude modulation
838135
de