| 摘要 |
PURPOSE:To shorten a synchronism acquisition time at the time of erroneous detection of frame synchronism. CONSTITUTION:A comparing part 5 outputs a detection signal when the output of an operation part 3 exceeds a threshold. A back protection part 6 starts back protection by the first detection signal to out-put, a count start signal. A count part 7 starts counting of the bit position by the count start signal. A storage part 8 integrates the frequency in output of the detection signal in each bit position. When discriminating that synchronism is not settled yet, the back protection part 6 outputs a synchronism unsettled signal. A control part 9 calculates the bit position, where the frequency in output of the detection signal is maximum, from the storage part 8 by the synchronism unsettled signal and compares it with the bit position from the count part 7 and outputs the difference as the shift time. The back protection part 6 starts the back protection operation again after the shift time, and this operation is repeated if frame synchronism is not settled yet. |
