PURPOSE: To decrease mis-detection of a communication control pattern in a general communication data by applying changeover control only when a reception data is a communication control pattern in which detection patterns are consecutive.
CONSTITUTION: When a reception data RD and a reception timing RT are converted into parallel data in N bit by a serial/parallel conversion circuit 1, exclusive OR gates 2-1 - 2-N compare detection patterns S1 - SN with parallel reception data RD1 - RDN by each bit. Comparison result signals E1 - EN are outputted at logical '0' when N-bits are coincident and at logical '1' when N-bits are dissident. Moreover, a NOR 6 outputs an output signal 6a whose one bit is logical 1 to a bit expansion circuit 7 while taking it as all bit coincidence when the comparison result signals E1 - EN are all logical 0, resulting that the parallel reception data RD1 - RDN and the patterns S1 - SN are all coincident with each other. Thus, mis-detection with respect to a random pattern is reduced.
TO HIDEO
UCHIDA YUKIO
OKI ELECTRIC IND CO LTD