| 摘要 |
PURPOSE:To control the generation of the uneveness of color based on the time constant of a voltage control oscillator and to correct a general time base fluctuation by providing a chrominance signal processing circuit consisting of an A/D converter, a demodulation circuit, a phase correction circuit, a modulation circuit or the like. CONSTITUTION:The chrominance signal sampled from a reproducing video signal is sampled initially in the A/D converter 22 based on the first clock signal having the frequency four times as long as chrominance subcarrier phase locked to a color burst signal. Then, the output of the converter 22 is digitally balance-demodulated through a band filter circuit 26 and the demodulation circuit 27 and a color difference signal is outputted. The signal is latched by the phase correction circuit 28 based on the second clock signal having the frequency four times as long as the chrominance subcarrier phase locked to a horizontal synchronizing signal. The output of the circuit 28 is digitally balance-modulated by the modulation circuit 29 and the chrominance signal is outputted. In this manner, the chrominance signal frequency in which the frequency is stabilized by the digital signal processing is changed by tuning with the time base fluctuation of the horizontal synchronizing signal, thereby the generation of the uneveness in the color can be controlled.
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