Multiplex communications – Diagnostic testing – Fault detection
Patent
1997-09-10
2000-11-28
Rao, Seema S.
Multiplex communications
Diagnostic testing
Fault detection
370242, 370248, 379 26, G01R 3108, H04M 124
Patent
active
061544477
ABSTRACT:
In switching centers serving multiple local access providers, a problem arises in detecting cable failure and identifying the provider of the failed cable connected between the switching center and remote terminals. A test circuit installed in each cable port of the switching center detects failed cables; identifies the operator of the failed cable, and designates the cable end at which the failure occurs. The test circuit includes a signal detector and a signal generator and monitor connected through a switching device to the cables. A data signal Ds is transmitted on the cables. When the detector recognizes a loss of a data signal Ds exceeding a threshold a failed cable has occurred at one end of the cable or the other. The switch is activated by the signal loss to connect the signal generator and monitor to determine at which cable end the cable has failed. A reference signal Rs is injected into a cable by the signal generator and monitor. If the data signal Ds on the failed cable matches the reference signal Rs in amplitude and phase, a cable failure is indicated at the near end of the cable detector. If the data signal Ds is degraded in amplitude and shifted in phase relative to the reference signal Rs, a cable failure is indicated at the far end of the cable.
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AT&T Corp.
Rao Seema S.
Tsegaye Saba
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