CHROMINANCE SIGNAL PROCESSING CIRCUIT

摘要

PURPOSE:To make the hue adjustment unnecessary by obtaining a demodulation carrier having a demodulation axis constant in phase because of vector signal synthesizing ratio is different even if a phase difference between 1st and 2nd vector signals is changed due to switching of oscillation frequency. CONSTITUTION:A VCO31 has resonators 32 and 33 for processing carrier chrominance signals of 3.58MHz and 0.43MHz, and either of the resonators is selected by a switch 34. An oscillation signal of vectors (a) and (b) is produced by a phase-shifting circuit consisting of a resistance Ro and capacitor Co. Values of the resistance Ro and capacitor Co are selected so that the vectors (a) and (b) can have phases of 45 deg. when the oscillation frequency of the VCO31 is 4.43MHz. The VCO31 provides a phase synthesization/switching circuit 311 on an R-Y demodulation carrier signal processing part, and controls so as not to fluctuate a demodulation axis of a carrier signal R-YCW when carrier chrominance signals of 3.58MHz and 4.43MHz are processed.