| 摘要 |
A synchronizing signal separator which forms reference synchronizing signals adapted to a digital signal processing circuit from input composite video signals including three-value synchronizing signals. A negative peak in the input composite video signals is clamped by a peak clamp circuit (3), and the clamped output is fed to a pulse generating circuit (4) to form a first pulse having a width spanning from a front porch to a back porch. At the same time, the input composite video signal and a signal having a phase opposite to the input composite video signal are clamped by a pedestal clamp circuit (6), and the output of the clamp circuit (6) and the first pulse are input to differential amplifier circuits (7) and (8), respectively in order to obtain two pulse signals having the same polarity corresponding to negative and positive synchronizing signal portions of the three-value synchronizing signal in the input composite synchronizing signal. Using the center of the pair of pulse signals as a synchronizing reference, it is allowed to form a reference synchronizing signal maintaining high precision to realize favorable video reproduction. |
