SECAM (Sequentiel Couleur avec Mémoire, French for "sequential color with memory") is an analog television system, using frequency modulation to encode chrominance information. It is so named because it uses memory to store lines of color information, in order to eliminate the color artifacts found on systems using the NTSC standard.
It was developed for the same purpose as PAL, but uses a different (and many would argue inferior) mechanism to do so. R-Y and B-Y information is transmitted in alternate lines, and a video line store is used to combine the signals together. This means that the vertical colour resolution is halved relative to PAL and NTSC.
SECAM was introduced in France in 1967, where it is still used; it has also been adopted in many former French colonies, as well as parts of Eastern Europe (Bulgaria, Hungary) and the former Soviet Union. Many have argued that the primary motivation for the development of SECAM in France was to protect French television equipment manufacturers and make it more difficult to view non-French programming. Political factors from the Cold War have also been attributed to the adoption of SECAM in Eastern Europe, as its use made it impossible for most Eastern Europeans to view television which was broadcast from outside the Iron Curtain which were mostly using PAL.
There are three varieties of SECAM:
Unlike PAL or NTSC, analog SECAM television could not easily be edited in its native form: instead, post-production was done in PAL, and the result then trans-coded into SECAM at the point of transmission.