A-MAC
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In television electronics, A-MAC is a form of analog video encoding, specifically a type of Multiplexed Analogue Components (MAC) encoding.[1] It 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.[2] A-MAC has not been used in service.[3]
Technical details
[edit]MAC transmits luminance and chrominance data separately in time rather than separately in frequency (as other analog television formats do, such as composite video).[4]
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.[5]
TV transmission systems
[edit]- Analog high-definition television systems
- PAL, what MAC technology tried to replace
- SECAM, what MAC technology tried to replace
- A-MAC
- B-MAC
- C-MAC
- D-MAC
- E-MAC
- S-MAC
- D2-MAC
- HD-MAC, an early high-definition television standard allowing for 2048x1152 resolution.
- DVB-S, MAC technology was replaced by this standard
- DVB-T, MAC technology was replaced by this standard
References
[edit]- ^ Report 1074-1 - Satellite transmission of multiplexed analogue component (MAC) vision signals (PDF). ITU. 1990. p. 48.
- ^ Slater, Jim (31 December 1991). Modern Television Systems. CRC Press. pp. 76–78. ISBN 978-0-273-03122-2. Retrieved 20 June 2025.
- ^ Lewis, Geoffrey E. (1992). Communication Services Via Satellite: A Handbook for Design, Installation and Service Engineers. Elsevier Science & Technology Books. p. 238. ISBN 978-0-7506-0437-6. Retrieved 20 June 2025.
A-MAC has not been adopted.
- ^ Money, Steve A. (1988). Newnes Radio Amateur and Listener's Pocket Book. Pearson Education New Zealand Limited. p. 75. ISBN 978-0-434-91259-9. Retrieved 20 June 2025.
In the multiplexed analogue components (MAC) system the luminance and chrominance signals are transmitted separately by using a time multiplexing system.
- ^ Schlyter, Paul (12 November 2000). "Multiplexed Analogue Components in 'Analog TV Broadcast Systems'". Archived from the original on 22 February 2025. Retrieved 20 June 2025.
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