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SECAM, also written SÉCAM (Séquentiel couleur à mémoire[1], French for "Sequential Color with Memory"), is an analog color television system first used in France. A team led by Henri de France working at Compagnie Française de Télévision (later bought by Thomson, now Technicolor) invented SECAM. It is, historically, the first European color television standard.


Technical details

Just as with the other color standards adopted for broadcast usage over the world, SECAM is a standard which permits existing monochrome television receivers predating its introduction to continue to be operate as monochrome television. Because of this compatibility requirement, color standards added a second signal to the basic monochrome signal, which carries the color information. The color information is called chrominance or C for short, while the black and white information is called the luminance or Y for short. Monochrome television receivers only display the luminance, while color receivers process both signals.

Additionally, for compatibility, it is required to use no more bandwidth than the monochrome signal alone; the color signal has to be somehow inserted into the monochrome signal, without disturbing it. This insertion is possible because the spectrum of the monochrome TV signal is not continuous, hence empty space exists which can be utilized. This lack of continuity results from the discrete nature of the signal, which is divided into frames and lines. Analog color systems differ by the way in which empty space is used. In all cases, the color signal is inserted at the end of the spectrum of the monochrome signal.

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