| 摘要 |
PURPOSE:To reduce the effect of noise, etc., by supplying and synchronizing the output signal of a synchronizing signal detecting circuit within a window formed by the 2nd window output generator when no output signal of a synchronizing signal circuit is supplied to the window of the 1st window output generator. CONSTITUTION:When a frame is out of synchronization owing to a drop-out, etc., a counter 7 counts up a prescribed number of frames by each frame by a window output generator 6. Then the output of the counter 7 is assumed as H. Then the output of a window generaor 12 goes to H to open a gate circuit 4 via a selector 8. The next synchronizing signal delivered from a synchronizing signal detecting circuit 3 is extracted through the gate circuit 4 to clear a frequency divider 5 and the counter 7. Hereafter the synchronizing signal fed from the circuit 3 is extracted through the circuit 4 which is opened by each frame by the output of the generator 6. Then the synchronization is secured between the circuit 3 and the divider 5. |
