SYNCHRONIZING SIGNAL DETECTING CIRCUIT FOR DIGITAL SIGNAL TRANSMISSION

摘要

PURPOSE:To prevent detecting a pseudo synchronizing signal as a synchronizing signal by outputting the output of a counter which is reset when the synchronizing signal output that is decided correct by an error check code is obtained continuously by the prescribed number of times. CONSTITUTION:The reproduction digital signal which is synthesized with a block unit of a prescribed signal format is supplied to an input terminal 1. This digital signal is supplied to a gate circuit 6 via a shift register 2, and the circuit 6 outputs the logic 1 as a detection signal when the data has the value of a fixed pattern equal to a prescribed synchronizing signal. Hereafter counters 10 and 22 are synchronous with each other by the detection signal supplied from the circuit 6 in a normal reproduction mode where the detection signal of the circuit 6 is continuously coincident by N times with the pulse synchronized in phase with the last bit of the synchronizing signal outputted from a decoder 12. Therefore a decoder 23 produces a pulse synchronized in phase with the final bit of the reproduction synchronizing signal. This output pulse is outputted through an output terminal 24 as a synchronizing signal detecting circuit.