| 摘要 |
PURPOSE:To facilitate design by extracting a cross modulation signal caused in a transmission line during a color burst period when no video signal component exists so as to detect the level of the cross modulation signal accurately. CONSTITUTION:A color television signal is a signal that a chrominance carrier signal is superimposed onto a black/white video signal (luminance signal) and a color burst is added to a horizontal blanking signal. That is, the timewise position of the color burst and video signal in exsitence differs from each other. Then in inputting the composite signal to a gate circuit 1 passing during the color burst period only, a synthesis signal in the color burst period being an output of the gate circuit 1 consists of the cross modulation signal, the video carrier signal, the chrominance subcarrier signal and the audio carrier signal and the video signal component is eliminated thereof. Thus, in detecting the level of an output (c) of the band pass filter 2 by a level detection circuit 3, the cross modulation signal level is detected accurately.
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