PROCESS FOR THE DEMODULATION OF SECAM-CODED COLOUR-TELEVISION SIGNALS WITH A LINE-COUPLED CYCLE, AND A CIRCUIT FOR CARRYING OUT THE PROCESS

摘要

In order to demodulate SECAM-coded colour-TV signals with a line-coupled cycle, a phase-stable colour carrier is first multiplied, in a first phase-control circuit, with a chrominance signal which is to be demodulated and then fed to a loop filter at whose output the demodulated chrominance signal is taken off. The phase-stable colour carrier is obtained by means of a digital follow-on oscillator whose output frequency is proportional to the product of an increment with the line-coupled cycle. The increment is formed by adding the demodulated chrominance signal to a correction signal selected so that it is at least approximately inversely proportional to the frequency of the line-coupled cycle.