| 摘要 |
PURPOSE:To make an asynchronous consecutive time zero substantially by constituting the equipment by a hunting means retrieving a frame synchronizing pattern and a frame signal supply means applying synchronizing control based on the internal state of the hunting means at the discrimination of out of syn chronism. CONSTITUTION:Suppose that a coincidence pulse going to appear in an output signal (a) at a time B in the synchronizing state is delayed till a time C, then a frame pulse appears in output signals (b), (c) at the time B, '0' appears in the output signal (d) and '1' appears in output signals (e), (f). The internal value of a synchronization protection counter 107 is expressed as n=1 and a clock control gate 108 is closed. Then a frame counter 110 starts hunting, a frame pattern detection circuit 103 detects a frame synchronizing pattern at a time C to open the clock control gate 108. This is equivalent to that the frame counter 110 ensures the frame synchronization and then a frame pulse appears in the output signals a, c succeedingly in the same phase. |
