| 摘要 |
PURPOSE:To realize a synchronizing signal protecting method in which erroneous propagation does not expand by complementing a missing of detection of synchronizing signals consecutive <=N times by means of a signal generated from the counting of clock, and not further complementing to the >N times. CONSTITUTION:A synchronizing signal in a reproducing signal is detected by a synchronizing signal detecting circuit 201 at first and the detected synchronizing signal is fed to a synchronizing signal selection switch 202. On the other hand, when a synchronizing signal is not found due to outer disturbance in a detection window formed by a detection window generating circuit 203, a synchronizing signal selection circuit 205 is activated by a control signal 204 to connect the synchronizing signal selection switch 202 to a backup counter 206 thereby complementing the synchronizing signal. When the missing of detection of the synchronizing signal exceeds a prescribed value N, a missing detection number counter 207 transmits a control signal to the synchronizing signal selection circuit 205 via an OR gate 208, the synchronizing signal selection switch 202 is thrown to the synchronizing signal detection circuit 201 and the complemention of the synchronizing signal is not performed.
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