| 摘要 |
In a control signal generator, a first frequency dividing circuit controllably frequency divides a television subcarrier signal to deliver a first frequency divided signal to a phase lock loop, which drives a logic circuit to produce a control signal for use in a television signal codec. Together with the first frequency divided signal, a second frequency divided signal produced by frequency dividing horizontal or vertical synchronizing signals, is supplied to a phase control circuit for phase controlling the first frequency divided signal so as to keep a phase difference which the first frequency divided signal has relative to the second one, within a prescribed tolerance. When the phase difference is smaller and not smaller than the tolerance, a switch may selectively supply the phase lock loop with the first and the second frequency divided signals, respectively, with the first frequency divided signal phase controlled to the tolerance if the phase difference is not within the tolerance.
|
