| 摘要 |
PURPOSE:To prevent color irregularity at demodulation of video signal in code modulation, by comparing the theoretical value of sample data of burst signal part with the size of actual sample data and making constant the phase of a sampling pulse. CONSTITUTION:An output of an A/D converter is applied to latch circuits 14A, 14B, 14C, where store the sample data of burst part of a video signal according to an address signal. The output of the latch circuits 14A, 14C is applied to pedestal level subtraction circuits 15, 16 respectively and figure corresponding to imaginary pedestal level is subtracted. The data are applied to a 147 deg. data calculation circuit 17 to calculate the theoretical value. The theoretical value and the actual value obtained from the latch circuit 14B are compared at a level comparison circuit 18, and a DC control voltage formed with a discrimination pulse is applied to a phase shifter 6. |
