| 摘要 |
PROBLEM TO BE SOLVED: To follow up a phase in wide range with respect to the phase fluctuation of an input signal by providing a means for selecting one of plural systems of phase synchronizing means and serial-parallel conversion means, and a means for switching these systems. SOLUTION: Two phase synchronizing circuits consisting of phase judging circuits 101 and 102, control circuits 111 and 112, and a variable delay circuit 120 follow up the phase of a delay clock with respect to the input signal whose phase fluctuates hourly. A synchronizing pattern detecting circuit 13X (X is 1 or 2) detects the synchronizing pattern of a transferring signal, and a serial- parallel conversion circuit 14X divides the frequency of the delay clock outputted from the circuit 120 to generate a slow clock and makes an input signal a parallel signal synchronizing with the slow clock to output. A system selection control circuit 150 outputs a switching signal for switching a nonselected system to a selected system to a system selecting circuit 151 at the time of recognizing that the failure of the phase following up of the selected system is near, from the output signals of the circuits 111 and 112 and the outputs of the circuits 101 and 102. |
