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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

B-MAC[1] is a form of analog video encoding, specifically a type of Multiplexed Analogue Components (MAC) encoding. MAC encoding was designed in the mid 80s for use with Direct Broadcast Satellite systems. Other analog video encoding systems include NTSC, PAL and SECAM. 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)

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 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.

See also


  1. ^ Report 1074-1 - Satellite transmission of multiplexed analogue component (MAC) vision signals (PDF). ITU. 1990. p. 48.
  2. ^ Conradie, D.G. (19 June 1988). "The SABC's TV/radio satellite distribution system". COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings. pp. 51–55. doi:10.1109/COMSIG.1988.49301. ISBN 0-87942-709-4. S2CID 131163463 – via IEEE Xplore.
  3. ^ "8.3 Multiplexed Analogue Components Transmissions".
  4. ^ "Scientific-Atlanta's PowerVu Technology Helping AFRTS Expand the Delivery of A Touch of Home to Military Abroad" (Press release). Atlanta, GA: Scientific Atlanta. PR Newswire. Retrieved 2014-05-29.

External links

This page was last edited on 20 September 2023, at 14:15
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