Telephonic communications – Subscriber line or transmission line interface
Patent
1991-06-07
1994-07-26
Dwyer, James L.
Telephonic communications
Subscriber line or transmission line interface
379402, 379403, 379404, H04M 1900
Patent
active
053331923
ABSTRACT:
A line interface circuit for coupling signals between a telephone line and a hybrid circuit includes a loop driver circuit for supplying energizing current to the telephone line and for driving the telephone line with alternating current signals. A loop current detector connected in series between the telephone line and the loop driver circuit, generates a voltage signal in response to current flow in the telephone line. Amplifier circuits are arranged to be responsive to differential signals on the telephone line, and to signals from the hybrid circuit, for generating a composite signal. The composite signal and the voltage signal are combined in a network having an output connected to control the operation of the loop driver circuit so that the telephone line is terminated with a preferred impedance.
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Radio Shack's Linear Applications vol. I p. AN31-10; Nov. 1967.
Dwyer James L.
Northern Telecom Limited
Shehata M.
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