Telephonic communications – Supervisory or control line signaling – Using line or loop condition detection
Patent
1994-10-27
1997-11-25
Zele, Krista M.
Telephonic communications
Supervisory or control line signaling
Using line or loop condition detection
379399, 379413, 379414, H04M 100
Patent
active
056920415
ABSTRACT:
A telephone subscriber circuit is coupled via a single galvanic isolation element to provide, from a subscriber apparatus unconnected to the telephone line, on- and off-hook signals to the telephone line and to control transfer of telephonic signals between the subscriber apparatus and the telephone line. The galvanic isolation element is a photocoupler. The subscriber circuit includes a speech circuit coupled to the line through a diode bridge circuit and an electronic switch is connected between the speech circuit and the diode bridge circuit. An input terminal of the speech circuit and a control terminal of the electronic switch are each connected through a voltage-generating circuit and level-translating circuit to an output terminal of the galvanic isolation element.
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Carlson David V.
SGS--Thomson Microelectronics S.r.l.
Tegreene Clarence T.
Wolinsky Scott
Zele Krista M.
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