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A-MAC

From Wikipedia, the free encyclopedia
The simultaneous PAL transmission of all TV-picture elements and the multiplexed transmission of the TV picture elements with D2-MAC.
Simulated MAC signal. From left to right: digital data, chrominance and luminance

In television electronics, A-MAC carries digital information: sound, and data-teletext on an FM subcarrier at 7 MHz. Since the vision bandwidth of a standard MAC signal is 8.4 MHz, the horizontal resolution on A-MAC has to be reduced to make room for the 7 MHz carrier. A-MAC has not been used in service.

Technical details

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MAC transmits luminance and chrominance data separately in time rather than separately in frequency (as other analog television formats do, such as composite video).

Audio and Scrambling (selective access)

  • Audio, in a format similar to NICAM was transmitted digitally rather than as an FM subcarrier.
  • The MAC standard included a standard scrambling system, EuroCrypt, a precursor to the standard DVB-CSA encryption system.

TV transmission systems

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