Protection channel monitoring system using a check signal comprising two different N-bit code patterns sequentially arranged at random

摘要

A protection channel monitoring system for monitoring a protection channel in a digital communication network comprises a transmitter (31) transmitting a check signal converted and split into a plurality of AMI code signals through the protection channel. The check signal is formed from a pseudo random signal provided by a pseudo random signal generator (15) driven by a pulse signal having a 1/N (N being an integer larger than 1) frequency of a clock pulse signal. The check signal comprises two predetermined N-bit code patterns each comprising logical "0" and "1" level bits. A receiver (32) receives the split AMI code signals through the protection channel and decode the AMI code signals to the NRZ code signals by sampling technique using a sampling signal being derived from one of the received AMI code signals and having the 1/N frequency of the clock pulse signal. Condition of the protection channel is decided by comparison of the decoded NRZ code signals.