Method for determining errors in a digital transmission system

摘要

In the method described for determining errors in a digital transmission system with repeater stations, it is assumed that a testing terminating exchange sends out a fault locating signal instead of the useful signal. The fault locating signal contains a test pulse pattern and information on the address of a repeater station to be located. The address is recognised in the repeater stations either digitally by means of counters or by analogue means with filters. The filters respond to frequencies which are contained as fundamental frequency in the pulse density fluctuations of the fault locating signal. To obtain as large a set of addresses as possible, by means of which both repeater stations with analogue and with digital address recognition can be located, it is provided to build up the fault locating signals on two bit patterns. The first bit pattern consists of a first bit sequence which is followed by the totality of all inverted bits of the sequence and the second bit pattern consists of a second bit sequence which is only followed by some of the inverted bits of the sequence. The number of inverted bits of each second bit pattern should be smaller than the smallest number of the inverted bits of all first bit patterns. The fault locating signals consist either of the periodic repetition of the first bit pattern or of the period repetition of the second bit pattern.