Error detection for digital transmission systems - uses command and test words inserted as scrambled text. into frame structure

摘要

The circuitry is used for producing an error detection code which can be used with intermediately regenerated scrambled 565Mbit/AMI/s/digital transmission lines. The frame alignment word (RKW) is transmitted and the command (KT) and test words (PT) are inserted in the frame structure. The tests are intended for out-of-service checks using loop backs from the intermediate regenerators. Four tributaries (1,2,3,4) are connected into changeover switches (6,7,8,9) prior to being connected through exclusive-OR gates (10,11,12,13) into the 565Mbit/s Multiplexer (MUX). The changeover switches (6,7,8,9) are provided with a control input(St) for changeover to receive the scrambled command words (at K1,K2) on the input of each tributary(at 6,7,8,9). The test word are clocked, using sync clock sources (TL1,2,3,4), from the pseudo random scramble text generator (PN) into the exclusive-OR gates (10,11,12,13) for mod-2 addition and transmission through the multiplexer (MUX). The command words are related in length to the number of tributaries in the system and the spectral content is related to attenuation and the Nyquist characteristics of the line.