| 摘要 |
In PCM telecommunications switching systems, a double connection is in each case set up to monitor connections or sections thereof, the routes of both arms of which are selected independently of one another in the route search via the switching network(s) and, if necessary, via PCM routes. The data stream passes from the branching point concerned via both arms, and the two data streams arriving at the other end of the double connection concerned are compared here with one another. A comparison in each case monitors isochronous sections from the branched data stream and begins with PCM words which are identical in terms of their time-slot pattern in relation to the consecutive pulse frames. In the event of non-correspondence, further comparison procedures follow in which the relevant sections from the branched data stream have a time-slot pattern difference of one or two pulse frames, a pulse frame difference being defined in both one temporal direction and in the other temporal direction. <IMAGE>
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