| 摘要 |
A sync separator detects the occurrence of a corresponding sync pulse in a corresponding part of the waveform of a composite video signal (100). The level (ST2) of the sync tip is used for updating a sync tip signal (ST), provided the level of the sync tip is lower than that of the sync tip signal. A time-out signal (TO) is generated (by 30) at the end of a time-out interval that has elapsed from the last time the sync tip signal (ST) was updated, provided the sync tip signal was not updated within such time-out interval. The time-out signal (TO) is used for updating the sync tip signal (ST). The sync tip signal is updated according to such sync pulse that occurred during the time-out interval, having the lowest level sync tip (ST1). Information obtained from the sync tip and the back porch portions of the corresponding sync pulse is used for generating a slice level signal (SL). A comparator (20) responsive to the slice level signal separates a sync signal (100a) from the composite video signal. |
