D-MAC


Among the family of MAC or Multiplexed Analogue Components systems for television broadcasting, D-MAC is a reduced bandwidth variant designed for transmission down cable.
D-MAC consumed too much bandwidth for many applications, so D2-MAC was designed for European cable TV systems.

Luminance and chrominance

MAC transmits luminance and chrominance data separately in time rather than separately in frequency.

Audio and scrambling (selective access)

MAC was developed by the UK's Independent Broadcasting Authority and in 1982 was adopted as the transmission format for the UK's forthcoming direct broadcast satellite television services. The following year MAC was adopted by the European Broadcasting Union as the standard for all DBS.
By 1986, despite there being two standards, D-MAC and D2-MAC, favoured by different countries in Europe, an EU Directive imposed MAC on the national DBS broadcasters, to provide a stepping stone from analogue PAL and Secam formats to the eventual high definition and digital television of the future, with European TV manufacturers in a privileged position to provide the equipment required.
However, the Astra satellite system was also starting up at this time and that operated outside of the EU’s MAC requirements, due to being a non-DBS satellite. Despite further pressure from the EU, most broadcasters outside Scandinavia preferred the lower cost of PAL transmission and receiving equipment.
In the 2000s, the use of D-MAC and D2-MAC ceased when the satellite broadcasts of the channels concern changed to DVB-S format.