CLOCK SUPPLY SYSTEM

摘要

PURPOSE:To improve the reliability of transmission of an overhead signal by using a reference clock signal from a highly stable in-equipment reference clock source for phase synchronization of a PLO so as to implement section overhead signal multiplexing when an input clock signal is interrupted. CONSTITUTION:An input clock interruption detection section 2 detects interruption of a clock signal C3 inputted as a co-directional clock signal of a data signal D2 from a clock transfer memory section 1 and outputs a clock selection control signal X1. A clock selection section 3 receives an in-equipment reference clock signal C2, the clock signal C3 and the clock control signal X1. Upon the receipt of the clock control signal X1 due to the interruption of the clock signal C3, the section 3 outputs the in-equipment reference clock signal C2 as a PLO synchronizing signal C4. A PLO 4 receives a PLO synchronization clock signal C4 and outputs a PLO output clock signal C5 phase-locked to the PLO synchronization clock signal C4.