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A marker at a central-office terminal, controlling the establishment of connections between local subscriber lines and inter-office links via an associated line concentrator/distributor, includes a source of d-c test signals of reversible polarity connectable in a phantom circuit which extends from...
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Main Author | |
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Format | Patent |
Language | French |
Published |
10.09.1976
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Subjects | |
Online Access | Get full text |
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Summary: | A marker at a central-office terminal, controlling the establishment of connections between local subscriber lines and inter-office links via an associated line concentrator/distributor, includes a source of d-c test signals of reversible polarity connectable in a phantom circuit which extends from the central office via a transmitting and a receiving branch of a local line to a subscriber station tied to that line. The subscriber station has a master switch, establishing either an inactive position or a standby position, and a hook switch closable in the standby position to initiate or accept a call. Depending on the positions of these two switches, a current discriminator at the marker detects one of three current levels (zero, low or high) with either polarity of the test signal to determine whether a call can go through or whether an alarm condition exists. |
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Bibliography: | Application Number: FR19750035634 |