How SECAM video standard works?
Like PAL, SECAM also has 625 scan lines and is based on 50 Hz. SECAM uses two color difference signals and modulates them onto alternate lines, and through a built in delay both are available at the same time. This eliminates phasing, and with FM transmission, and color recovery so good, saturation was unnecessary.
While NTSC and PAL transmit the luminance and chrominance signals simultaneously, SECAM transmits luminance continuously and generates only one of the two chrominance signals on any given line. The frame rate is 25 frames per second (It has a field rate of fifty fields per second) to provide compatibility with the European electrical supply frequency, and the number of scanning lines is 625 as in PAL. SECAM has a horizontal rate of 15.625 KHz. SECAM suffers from the visibility of the sub-carrier signals particularly in the mid-gray and white signals. This visibility detracts from its black and white compatibility.
SECAM is not compatible with PAL or NTSC.