| 摘要 |
PURPOSE:To attain accurate switching of a circuit constant by forming a gate pulse based on an FM luminance signal to make the switching operation stably even if a dropout takes place or noise is mixed. CONSTITUTION:The 1st or the 2nd color video signal reproduced by a head HP is fed to an FM demodulator 3 via a preamplifier 2 and the 1st or the 2nd luminance signal is demodulated. Furthermore, an output of the preamplifier 2, that is, an FM luminance signal component in the 1st or 2nd color video signal before the demodulation is fed to a discriminating circuit 20. The discriminating circuit 20 has at least a filter of single peak characteristic and a detection circuit and a different discriminated output is formed based on the difference between the said 1st or 2nd color video signal and the detection level of a horizontal synchronizing pulse. This discriminated output is fed to a switching circuit 6 as a gate pulse PG and an output from one of LPF1, LPF2 with different frequency band is selected.
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