Telephonic communications – Diagnostic testing – malfunction indication – or electrical... – Testing of subscriber loop or terminal
Patent
1986-02-10
1987-07-21
Schreyer, Stafford D.
Telephonic communications
Diagnostic testing, malfunction indication, or electrical...
Testing of subscriber loop or terminal
379 6, H04B 346
Patent
active
046823476
ABSTRACT:
Method and apparatus for selecting a single telephone line from among multiple line pairs at a location remote from the central office and isolating that line from the respective subscriber line to allow the performance of line tests on same. Line pairs are sampled sequentially for a short time interval of about 35 ms to determine whether a signal is present within an initial detection band, that band having a range about .+-.100 hz of the test signal frequency. If a signal is found, the system shifts to a validation mode to detect a signal within a range of about .+-.10 hz of the test signal frequency during a preselected long time interval. The system remains in validation mode for about six iterations of the validation routine, each long time interval being about 0.5 seconds duration. Upon finding a signal present at the end of each such validation cycle, the system disconnects the selected line from its respective subscriber line and begins performing line tests to diagnose problems.
REFERENCES:
patent: 3711661 (1973-01-01), Garrett et al.
Keptel, Inc.
Schreyer Stafford D.
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