GB1394793A - Fault detecting arrangements in pcm telecommunication systems - Google Patents

Abstract

1394793 Repeater fault locating SIEMENS AG 19 March 1973 [30 March 1972] Heading H4R In a fault locating system for the repeaters of a pem communications system, at a transmitting station 1 a first generator 15 feeds the line with a test pulse pattern comprising a synchronizing word composed of pulse code element pairs "11" and "00" which are each interposed in an alternating sequence between an equal number of modulatable pulse code elements. The station 1 also includes a modulator 3 which operates on the modulatable elements of the test pulse pattern and which is controlled by a rectangular waveform generator 2 the frequency of which can be set to the characteristic frequency of a band pass filter 11 of the repeater station 8 which it is desired to test. Detection of that frequency in the transmitted test pulse pattern at the repeater causes a looping of the go and return paths at that repeater and return of the test pulse pattern to a comparator 4 where the synchronizing word is compared with a word generated in 16, which is synchronized to the test pulse pattern of generator 15, and the fault rate is indicated on indicator 5. In an alternative arrangement, Fig. 2 (not shown), looping takes place between two "go" lines and the comparator, generator 16, and indicator 5 are located at a different terminal station. The testing apparatus can be constructed as a portable locating device.