US 4,365,248 AGranted

Digital transmission link relief triggering system

AssigneeSociete Anonyme de Telecommunications

InventorsGilbert L. Bargeton, Claude P. Beynie

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Abstract

The system triggers the relief of a working line amongst N working lines in a bidirectional digital transmission link having at least one spare line. The link is interconnected between two end stations (A, B) which allow a switch-over between a faulty working line and a spare line. The relief of a working line is triggered in response to the detection of an alarm indication signal (AIS) delivered by any end or intermediary terminal included in the working line. An AIS coming from outside the link and related to the working line is detected in an end station and replaced by a switching inhibiting signal that is transmitted via the working line, or perhaps via a spare line, should the working line be faulty and previously relieved, and that is detected in the other station and then replaced by an AIS transmitted outside the link in relation to the other station.

Claims12

Dependent claims

An end station for triggering relief of a working line in a bidirectional digital transmission link of a digital transmission system, the link having a plurality of bidirectional digital transmission working lines and a plurality of bidirectional digital transmission spare lines, the link being interconnected between two of the end stations, said end station comprising:

first detecting means for detecting a first digital alarm indication signal derived from outside of said link,
first replacing means controlled by said first detecting means for replacing a first detected outside alarm indication signal by a first digital switching inhibition signal, said end station normally transmitting the first digital switching inhibition signal through said working line and transmitting the first digital switching inhibition signal on a spare line when said working line has failed and been relieved,
second detecting means for detecting a second digital alarm indication signal derived from another end station or any intermediary station on said working line, said second means triggering switch-over from said working line to a spare line in said end station,
third detecting means for detecting a second digital switching inhibition signal delivered from said first replacing means of another the end station on said working line, and
second replacing means controlled by said third detecting means for replacing said second switching inhibition signal by a second alarm indication signal, as derived from outside of said link and coupled to the end station via the link.

2 more elements

Dependencies are inferred from the claim text.