SECAM

SECAM, also written SÉCAM (French pronunciation: [sekam],Système Électronique Couleur Avec Mémoire, French for electronic colour system with memory), is an analogue colour television system that was used in France, Russia, and some other countries or territories of Europe and Africa. It was one of three major analog colour television standards, the others being PAL and NTSC. Like PAL, a SECAM picture is also made up of 625 interlaced lines and is displayed at a rate of 25 frames per second (except SECAM-M). However, due to the way SECAM processes colour information, it is not compatible with the PAL video format standard. SECAM video is composite video; the luminance (luma, monochrome image) and chrominance (chroma, color applied to the monochrome image) are transmitted together as one signal.

All the countries using SECAM have either converted to Digital Video Broadcasting (DVB), the new pan-European standard for digital television, or are currently in the process of conversion. SECAM remained a major standard into the 2000s.

Development of SECAM predates PAL, and began in 1956 by a team led by Henri de France working at Compagnie Française de Télévision (later bought by Thomson, now Technicolor). NTSC was considered undesirable in Europe because of its tint problem, requiring an additional control, which SECAM (and PAL) solved.

Some have argued that the primary motivation for the development of SECAM in France was to protect French television equipment manufacturers. However, incompatibility had started with the earlier unusual decision to adopt positive video modulation for 819-line French broadcast signals (only the UK's 405-line was similar; widely adopted 525- and 625-line systems used negative video).

The first proposed system was called SECAM I in 1961, followed by other studies to improve compatibility and image quality, but it was too soon for a wide introduction. A version of SECAM for the French 819-line television standard was devised and tested, but never introduced.

Following a pan-European agreement to introduce colour TV only on 625-line broadcasts, France had to switch to that system, which happened in 1963 with the introduction of "la deuxième chaîne ORTF" France 2, the second national TV network.

Further improvements during 1963 and 1964 to the standard were called SECAM II and SECAM III, with the latter being presented at the 1965 CCIR General Assembly in Vienna, and adopted by France and the Soviet Union.

Soviet technicians were involved in a separate development of the standard, creating an incompatible variant called NIIR or SECAM IV, which was not deployed. The team was working in Moscow's Telecentrum. The NIIR designation comes from the name of the Nautchno-Issledovatelskiy Institut Radio (NIIR, rus. Научно-Исследовательский Институт Радио), a Soviet research institute involved in the studies. Two standards were developed: Non-linear NIIR, in which a process analogous to gamma correction is used, and Linear NIIR or SECAM IV that omits this process. SECAM IV was proposed by France and USSR at the 1966 Oslo CCIR conference and demonstrated in London.