<!--*** Article has no intro or context. ***-->B-MAC
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
. 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 Australia for TVRO until 2004.
- B-MAC has not been used for DTH applications since Primestar switched to an all-digital delivery system in the mid-1990s.
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......