Synchronisation supervising method and device in a time division multiplex system

摘要

1. A method of monitoring the synchronisation of a t.d.m. system and of initiating resynchronisation at a predetermined value of the frequency of non-conformity between an expected frame code word and the bit pattern actually occuring at this position, characterized in that at the transmitting end, during a determinate measuring period (M1, M3, M5... Mn), in a determinate time relationship to the frame code, it is determined whether the sum of all the transmitted bits of a logic state is even or odd, that a parity bit is formed, the logic status of which provides a statement as to whether evenness or oddness has been determined, that the parity bit is inserted into an unoccupied time slot of the pulse frame, that at the receiving end, during the same measuring period, in the same time relationship to the recognised but possibly incorrect frame code, it is determined whether the sum of all the received bits of the logic state which has been selected at the transmitting end is even or odd and that the receiving-end result is compared with the statement contained in the received parity bit.