Demodulation circuit for a digitized chrominance signal having a sampling signal oscillator coupled to a chrominance signal oscillator

Claim 1

A demodulation circuit for a digitized chrominance signal of a color television signal sampled by means of a sampling signal at a sampling frequency, which circuit comprises a first digital oscillator for obtaining from the sampling signal a digitized reference signal of the subcarrier frequency of the chrominance signal, occurring at the sampling frequency, for demodulating this chrominance signal, for which purpose a phase control signal input of the digital oscillator is coupled to an output of a color synchronization signal phase detection circuit, characterized in that the sampling signal is obtained, by means of a second digital oscillator, from a signal source of a constant frequency, phase control signal input for a digital number of this second digital oscillator being coupled to an output of a phase detection circuit, as a result of which the frequency and phase ratio between the sampling signal and a signal of the horizontal deflection frequency is kept constant, which input for the digital number is further coupled to an input of a divide circuit for dividing a digital number, obtained from an output of the color synchronization signal phase detection circuit, by the digital number, an output of this divide circuit being coupled to the phase control signal input of the first digital oscillator.