Multiplexed Analogue Components transmission (real signal)

D2-MAC is a

satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...

transmission standard, a member of

Multiplexed Analogue Components Multiplexed Analogue Components (MAC) was an analog television standard where luminance and chrominance components were transmitted separately. This was an evolution from older color TV systems (such as PAL or SECAM) where there was interferen ...

family. It was created to solve

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. * The data is Bipolar encoding, duobinary coded with a data burst rate of ...

's bandwidth problem on European cable systems. * D2-MAC uses half the data rate of

* D2-MAC has a reduced vision bandwidth, about 1/2 that of D-MAC. * D2-MAC retains most of the quality of a

signal—but consumes only 5 MHz of bandwidth.

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 Near Instantaneous Companded Audio Multiplex (NICAM) is an early form of lossy compression for digital audio. It was originally developed in the early 1970s for point-to-point links within broadcasting networks.Croll, M.G., Osborne, D.W. and Spi ...

was transmitted digitally rather than as an FM sub-carrier. * The MAC standard included a standard scrambling system, EuroCrypt, a precursor to the standard DVB-CSA encryption system.

History and politics

MAC was developed by the UK's

Independent Broadcasting Authority The Independent Broadcasting Authority (IBA) was the regulatory body in the United Kingdom for commercial television (ITV and Channel 4 and limited satellite television regulation – cable television was the responsibility of the Cable Authorit ...

(IBA) and in 1982 was adopted as the transmission format for the UK's forthcoming

direct broadcast satellite Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...

(DBS) television services (eventually provided by

British Satellite Broadcasting British Satellite Broadcasting (BSB) was a television company, headquartered in London, that provided direct broadcast satellite television services to the United Kingdom. They started broadcasting on 25 March 1990. The company was merged with ...

). The following year MAC was adopted by the

European Broadcasting Union The European Broadcasting Union (EBU; french: Union européenne de radio-télévision, links=no, UER) is an alliance of Public broadcasting, public service media organisations whose countries are within the European Broadcasting Area or who ar ...

(EBU) 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 Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

and

SECAM SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...

formats to the eventual high definition and

digital Digital usually refers to something using discrete digits, often binary digits. Technology and computing Hardware *Digital electronics, electronic circuits which operate using digital signals **Digital camera, which captures and stores digital i ...

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 (the first satellite,

Astra 1A Astra 1A was the first satellite launched and operated by SES (Société Européenne des Satellites), launched in December 1988. During its early days, it was often referred to as the Astra Satellite, as SES only operated one satellite original ...

was launched in 1989) and that operated outside of the EU's MAC requirements, due to being a non-DBS satellite. Despite further pressure from the EU (including a further Directive originally intended to make MAC provision compulsory in TV sets, and a subsidy to broadcasters to use the MAC format), 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 concerned changed to

DVB-S Digital Video Broadcasting – Satellite (DVB-S) is the original DVB standard for Satellite Television and dates from 1995, in its first release, while development lasted from 1993 to 1997. The first commercial applications was by Star TV in Asia ...

format.''High Above'' Broadgate Publications (April, 2010).

References

{{reflist

External links

Multiplexed Analogue Components
in "Analog TV Broadcast Systems" by Paul Schlyter
Example of a raw D2-MAC transmission being received
Television technology Television transmission standards Video formats British inventions 1982 introductions Audiovisual introductions in 1982

Technical details

History and politics

See also

References

External links