système en couleur à mémoire (TV) (SECAM)

The three color television standards NTSC, PAL and SECAM differ primarily in the modulation of the color signals, whereby the frame rate and the number of lines can vary nationally.

The SECAM process, developed in France, works line-sequentially in the color representation. For example, the color difference signal R-Y is displayed in the first line, B-Y in the following line, followed in turn by R-Y in the third line, and so on. In the receiving equipment, the lines are inter-delayed and displayed in two successive lines. This means that two successive lines have identical color information. This is compensated by the reduced color resolution capacity of the human eye.

Another major difference from SECAM is the modulation method used for the color signals. The color carrier has a frequency of 4.406 MHz or 4.25 MHz.

SECAM modulates the chrominance signal in frequency modulation.

The SECAM full frame has the same resolution as PAL. It has 625 lines, 576 of which are visible, and a frame rate of 50 fields or 25 frames. The line frequency of 15.625 kHz therefore corresponds to that of the PAL television standard. Like the other television standards, SECAM works with the interlaced scanning method.