| 摘要 |
In a circuit arrangement for deriving digital color signals from an analog television signal by means of an A/D converter, which forms a digital television signal from the analog television signal in synchronism with a clock signal which corresponds to a whole multiple of the line frequency of the television signal, and further by means of a demodulator, a first phase detector, a first phase calculator and a signal generator, which are interconnected in a phase-locked loop, interference-free demodulation of the chrominance signal in the composite television signal is guaranteed, even when the frequency of the clock signal fluctuates, in that the first phase calculator is supplied not only with a color phase signal from the first phase detector but also with a reference phase signal from a reference circuit which is a measure of the frequency difference or phase difference between the clock signal and a reference signal of stable frequency.
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