B-MAC is a form of analog video encoding, specifically a type of

Multiplexed Analogue Components Multiplexed Analogue Components (MAC) was an analog television standard where luminance and chrominance components were transmitted separately. This was an evolution from older color TV systems (such as PAL or SECAM) where there was interferen ...

(MAC) encoding. MAC encoding was designed in the mid 80s for use with Direct Broadcast Satellite systems. Other analog video encoding systems include

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 ...

, PAL and

SECAM SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...

. Unlike the FDM method used in those, MAC encoding uses a TDM method. B-MAC was a proprietary MAC encoding used by Scientific-Atlanta for encrypting broadcast video services; the full name was "Multiple Analogue Component, Type B". B-MAC uses teletext-style non-return-to-zero (NRZ) signaling with a capacity of 1.625 Mbit/s. The video and audio/data signals are therefore combined at baseband. * Both PAL (626/50) and NTSC (525/60) versions of B-MAC were developed and used. User base (PAL/NTSC zones) * This system was used in South Africa and Australia (for TVRO until 2000). * B-MAC was used for satellite broadcasts of the American Forces Radio and Television Service from the early 1980s until 1996-1997 when the analogue standard was replaced by the digital PowerVu system. * B-MAC has not been used for DTH applications since Primestar switched to an all-digital delivery system in the mid-1990s.

Technical details

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 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 Sp ...

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.

References

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External links

Multiplexed Analogue Components
in "Analog TV Broadcast Systems" by Paul Schlyter Video formats Television technology

Technical details

See also

References

External links