Operation monitoring system for digital transmission link - checks received monitoring signal telegram each intermediate station

摘要

The monitoring system uses a data telegramme monitoring signal which is transmitted in parallel with the digital communication signal switch regeneration and updating of the data telegrammes at each intermediate station between the end stations. When reception of the data telegramme at an intermediate station is not obtained for a given interval, the intermediate station is switched into a start mode to begin transmission of its own data telegramme. Each intermediate station monitors the correct reception of the transmitted characters and compares the bit error rate with a threshold value, to initiate the start mode. ADVANTAGE - Allows localisation of transmission fault.