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 compirses a transmitter (3l) 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 (l5) driven by a pulse signal having a l/N (N being an integer larger than l) frequency of a clock pulse signal. The check signal comprises two predetermined N-bit code patterns each comprising logical "0" and "l" 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 l/N frequency of the clock pulse signal. Condition of the protection channel is decided by comparison of the decoded NRZ code signals.