FRAME PULL-IN METHOD

PURPOSE:To shorten the frame pull-in time by securing the block synchronization from a code rule and check bit and performing the hunting for each block to detect a frame synchronizing block running counter to the code rule. CONSTITUTION:The serial data 19 and a clock 20 synchronous with the data 19 are supplied to serial/parallel converter 11. Thus the data 19 is converted into a parallel data 21, and a signal 23 delivered from an exclusive OR circuit 22 is supplied to a synchronization detecting circuit 16. The clocks 20 are thinned by a gate circuit 14 and a 1/9-divider 15 is controlled. The parallel signal 28 is supplied to a frame synchronization detecting circuit 17 together with a signal 29 showing the presence or absence of an offense against the code rule. These signals 29 and 28 are hunted for each block for detection of the frame synchronizing position. Thus the frame pull-in time is shortened.