| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frame pulse switching circuit in which a multiplexed transmission is performed without occurrence of out-of-synchronism or alarm even when a synchronizing source frame pulse is switched. <P>SOLUTION: A phase difference in an output of a selector circuit S1 selected out of a plurality of inputted synchronizing source frame pulses (FP) and an output of a frequency divider M2 and an output of a frequency divider P15 is stored as a digital value and when the synchronizing source FP is switched, based upon a phase difference between a count value 504 comparing phases between the output of the selector circuit S1 and the output of the frequency divider M2 after switching and a stored value 505 just before FP interruption, output phase control is performed on the frequency divider M2. After the lapse of fixed time, based upon a phase difference between a count value 602 comparing phases between the output of the selector circuit S1 and the output of the frequency divider P15 after switching and a stored value 603 just before FP interruption, output phase control is performed on the frequency divider M2 to hold a phase difference in an ordinary state. <P>COPYRIGHT: (C)2004,JPO |
