| 摘要 |
PURPOSE:To attain optimum slice level to ghost at separation and to obtain stable vertical synchronizing signals, by performing the amplitude separation of a composite synchronizing signal after the composite video signal having stable pedestal level to the video signal change. CONSTITUTION:A pedestal level from a composite video signal input terminal 1 is clamped to a constant level at a clamp circuit 2, and the output of the circuit 2 is branched into two; one is applied to the 1st LPF13 of a clamp pulse generating circuit 12. The LPF13 separates the vertical synchronizing signal component, the peak value of the synchronizing signal is detected at a peak value detection circuit 14, the slice level is set at the 1st comparator 20, the output of a monostable multivibrator 21 is applied to the circuit 2 as a clamp pulse to close a switch 5 to attain the coincidence between the pedestal level and a reference voltage V1. When the pedestal level is made stable, the vertical synchronizing signal is outputted via the 2nd and 3rd comparators 22, 24 and the 2nd LPF23. |
