| 摘要 |
A television receiver incorporates synchronizing circuitry which provides different synchronizing characteristics to accommodate different program sources. Illustratively, for receivers having vertical countdown circuits, normal broadcast signal reception causes the vertical synchronizing window to be narrow and the AFC circuits to operate normally. When the video signals originate from a nonbroadcast source, such as a video tape recorder or a video disc player, the synchronizing window is caused to be wide and the AFC circuit speed is increased. The appropriate receiver synchronizing characteristic is selected in response to the selected channel input. |
