| 摘要 |
<p>PURPOSE:To attain synchronization protection to respect phase relation between a detecting synchronizing signal and digital data at a maximum by position-setting a detecting window with matching to the next detecting synchronizing signal when the detecting synchronizing signal does not exist in the detecting window over a constant period. CONSTITUTION:For a window method synchronization protecting circuit 11, the detecting window is provided to be corresponded to a 9 bit clock before and after the detecting period of a coming synchronizing signal from the counted value of the bit clock to be counted by a frame counter 15 between the detecting synchronizing signals. When the detecting synchronizing signal does not exist in the detecting window, it is assumed that the signal exists in the center of the detecting window and a protecting synchronizing signal is outputted. Then, when the detecting synchronizing signal does not exist in the detecting window over the constant period, the detecting window is position-set with being matched to the next detecting synchronizing signal by a window reset circuit 14. Thus, by resetting the detecting window, unconvenience that phase control is made so strict that a jitter is promoted is evacuated and the synchronization protection can be executed to respect the phase relation between the detecting synchronizing signal and the digital data at the maximum.</p> |
