1976-06-24
1977-09-06
Claffy, Kathleen H.
H04J 314
Patent
active
040469646
ABSTRACT:
A digital subscriber loop transmission system is disclosed through which a number of remote subscribers are serviced with a smaller number of time division channels.
The digital transmission system includes an automatic channel testing unit which selects digital channels one at a time and in sequence for a series of automatic tests. Channels which fail these tests are withdrawn from service.
One such test involves ringing and automatic number identification circuits by means of which subscribers' telephones are rung and the off-hook subscriber on a two-party line is identified, both by the use of supervisory codes in the digital pulse stream. These supervisory codes are used to test the supervisory circuits themselves and, incidentally, large portions of the overall system.
REFERENCES:
patent: 3250863 (1966-05-01), Pearce
patent: 3407274 (1968-10-01), Hribik
patent: 3529089 (1970-09-01), Davis
patent: 3678222 (1972-07-01), Boehly
patent: 3752940 (1973-08-01), Santulli
patent: 3829628 (1974-08-01), Tripsas
Daugherty Thomas Henry
Stone Dale Eugene
Bell Telephone Laboratories Incorporated
Claffy Kathleen H.
Nimtz Robert O.
Popek Joseph A.
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