multiplexed analog components (MAC)

With the MAC process(Multiplexed Analog Components), an attempt was made in the 1980s to establish a transmission standard for satellite television. The MAC development had the goal of transmitting high-definition television via satellite and scrambling it for pay TV using scramblers.

In order to achieve compatibility between the MAC process and the PAL television standard as easily as possible, certain technical characteristics of the European television standards were taken into account during development.

The MAC method and the various variants based on it are based on the time-division multiplexing of the components of the video signal: the luminance and the chrominance. The two signal components are transmitted in one line, each for half of the line duration. First the luminance signal, then, after half the line duration, the chrominance signal. For reasons of compatibility, the frame rates and line frequencies used in PAL television have been retained.

The MAC process has several variants. A-MAC, for example, worked with a frequency-modulated, digital sound signal. B-MAC had adopted the digital audio signal, but transmitted it in the blanking interval. C-MAC had a bandwidth of 27 MHz and was therefore only suitable for satellite transmission. It also used phase shift keying( PSK) for audio modulation. And D-MAC used a ternary modulation scheme for tone modulation. In D-MAC, the individual components of the TV signal - tone, luminance, chrominance - are multiplexed. In addition, D-MAC has up to eight audio channels.

All MAC methods mentioned were only tested, the only remaining one is D2-MAC.