| 摘要 |
PROBLEM TO BE SOLVED: To prevent the phase variation of the output of an extract reference signal generation circuit by self-traveling a first phase synchronous oscillator (PLO) and supplying the output of m-th PLO to the extracted reference signal generation circuit when a selected extract clock signal becomes abnormal. SOLUTION: When an extract clock switch circuit 19 detects that a selected extract clock signal is cut, a transmission clock signal that PLO 7 outputs is inputted to an extract reference 8k generation circuit 20, a switch 21 is controlled and the contact point is opened. Thus, PLO 5 becomes a self-traveling state. The extract clock switch circuit 19 selects a next normal extract clock signal and inputs the extract clock signal to the extract reference 8k generation circuit 20. The extract clock switch circuit 19 controls the switch 21, closes the contact point, inputs the output of the extract reference 8k generation circuit 20 to PLO 5 and restores PLO 5 from the self-traveling state. |
