| 摘要 |
PROBLEM TO BE SOLVED: To provide a clock-switching circuit which solves a system trouble by the drift/slip detection, in the event of a frequency failure in an input clock in a transmission system having a redundant structure. SOLUTION: A reception clock switching controller 15 is provided for switching-over clock switching circuits 12a, 12b, having redundant structures. The reception clock switching circuit 12a, 12b switch-over input clocks, when both system detect drift/slip alarms ALM7a, ALM7b of PLL circuits 13a, 13b. |
