Communications: electrical – Condition responsive indicating system – With particular coupling link
Patent
1990-02-02
1991-07-02
Crosland, Donnie L.
Communications: electrical
Condition responsive indicating system
With particular coupling link
340531, 340512, 340513, 340538, 379 48, 379 49, 379 39, 379 42, G08B 108
Patent
active
050292900
ABSTRACT:
An alarm system suitable for use in a telecommunications network in which a central switching system is capable of selectively providing a signal of a predetermined polarity to a plurality of remotely located stations without being dependent upon or impeding the ability of the central switching system to process relatively high volume communications traffic. Each of the remote stations is connected to the telecommunications network by an electrical conduction path. The stations are substantially unresponsive to the predetermined polarity signal. In response to an alarm indication signal, the system effects a reversal in the polarity of the signal provided to a selected subset of the remote stations. Each station in the selected subset responds to the polarity reversal by indicating an alarm condition.
REFERENCES:
patent: 3697984 (1972-10-01), Atkinson et al.
patent: 3707708 (1972-12-01), Dan
patent: 3748389 (1973-07-01), Casterline et al.
patent: 4060803 (1977-11-01), Ashworth, Jr.
Dudek Michael
Greenwald Brian D.
McGrath John J.
Parsons Donald F.
Parsons Leo D.
Communications Test Design, Inc.
Crosland Donnie L.
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