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 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 ...

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 TDM may refer to: * ''TDM (film), TDM'', a 2023 Indian Marathi language, Marathi comedy film * TDM (Macau) (), a Macanese radio and television network * The Yamaha TDM, a motorcycle model * Target Disk Mode, a boot mode on certain Macintosh compute ...

method. B-MAC was a proprietary MAC encoding used by

Scientific-Atlanta Scientific Atlanta, Inc. was a Georgia, United States-based manufacturer of cable television, telecommunications, and broadband equipment. Scientific Atlanta was founded in 1951 by a group of engineers from the Georgia Institute of Technology, an ...

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 Television receive-only (TVRO) is a term used chiefly in North America, South America to refer to the reception of satellite television from FSS-type satellites, generally on C-band analog; free-to-air and unconnected to a commercial DBS prov ...

until 2000). * B-MAC was used for satellite broadcasts of the

American Forces Radio and Television Service The American Forces Network (AFN) is a government television and radio broadcast service the U.S. military provides to those stationed or assigned overseas. Headquartered at Fort George G. Meade, Maryland, AFN's broadcast operations, which i ...

from the early 1980s until 1996-1997 when the analogue standard was replaced by the digital

PowerVu PowerVu is a conditional access system for digital television developed by Scientific Atlanta. It is used for professional broadcasting, notably by Retevision, Bloomberg Television, Discovery Channel, AFRTS, ABS-CBN, GMA Network, and American For ...

system. * B-MAC has not been used for DTH applications since

Primestar PrimeStar was a U.S. direct broadcast satellite broadcasting company formed in 1991 by a consortium of cable television system operators ( TCI Satellite Entertainment Group, Time Warner Cable, Cox Communications, Comcast and MediaOne) and GE A ...

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 Spi ...

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