| 摘要 |
PURPOSE:To eliminate the mis-discrimination of a video control signal by using a clamper to boost a pre-shoot signal component of a pedestal level or less up to a threshold level of a detector. CONSTITUTION:A signal demodulated into a video signal is amplified by an amplifier 9 and only a VPS signal part is extracted by a VPS extracting gate 10, the result is clamped by a clamper 11 and fed to a detector 5 through a buffer 12. Since the pre-shoot part is boosted to higher potential by the effect of the clamper 11, the level reaches the threshold level of the detector 5. Thus, the mis-discrimination of the VPS signal due to pre-shoot caused frequently at the start of the VPS signal is eliminated.
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