SYNCHRONOUS DETECTION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To improve the responsiveness of synchronous detection in a signal switching state by preparing an initialization means which compulsively outputs a synchronous undetected signal if the signals of a data series to be inputted are switched to each other. SOLUTION: When an input signal is switched to another, a switch signal (g) of a low level is inputted from an input terminal 102. A synchronous detection initialization part 10 compulsively sets the count value of a coincidence detection counter 3 and a non-coincidence detection counter 4 at 0 and 3 respectively. A synchronous detection decision part 5 outputs a signal (f) of a low level to show a synchronous undetected state. A synchronous counter 6 outputs in sequence the timing signals (c) to both counters 3 and 4 every time an output signal (b) of a pattern collation part 2 is inputted. When the count value of circuits 3 and 4 are set at 3 and 0 respectively, the part 5 outputs the signal (f) of a high level to show a synchronous detection state.