What is MESECAM?
MESECAM stands for Middle Eastern Secam. MESECAM is not a broadcast standard. It is a VCR “standard” by which the color under process in VCR's is done by subcarrier shift instead of by frequency division. This means that an original Secam recording (frequency division) does not play back in a MESECAM player.
MESECAM uses an AM subcarrier and SECAM uses FM subcarrier. When MESECAM records a color signal onto VHS or Betamax video tape, the luminance signal is recorded in its original form (albeit with some reduction of bandwidth) but the chrominance signal of about 4.4 MHz is too sensitive to small changes in frequency caused by inevitable small variations in tape speed to be recorded directly. Instead, it is first down converted to the lower frequency of 630 kHz, and the complex nature of the PAL sub carrier means that the down conversion must be done via a superhet mixer to ensure that information is not lost.
VCRs featuring MESECAM will record SECAM signals in such a fashion, that can be later viewed on PAL TVs. This system is incompatible with both PAL and SECAM, and a MESECAM VCR is required to play MESECAM tapes.