Communication system interface circuits

Details Communication system interface circuits Communication system interface circuits

Filed on

1973-11-13

Date issued

1977-03-08

Examiner

Claffy, Kathleen H.

Other Related Categories

179 78R, 179 2C, H04M 318

Type

Patent

Status

active

Patent number

040114104

Description

ABSTRACT:
Communication system interface circuits for bidirectional transmission of signals between terminal sets, each interface circuit comprising a transformer including first winding means coupled through rectifier means and a low-pass filter to a first terminal set and including second winding means having end terminals coupled through diodes to the output of a high frequency inverter and having a center tap coupled through an inductance impedance to a neutral circuit point, a second terminal set being coupled across the inductive impedance. The first terminal set may be connected to a telephone subset with ringing and bias signals being applied in circuit with the inductive impedance. The indictive impedance includes transistor means controlled by an operational amplifier which is controlled from a resistance-capacitance phase-shift means, the impedance being equivalent to that of an inductance and a series resistance.

REFERENCES:
patent: 2794857 (1957-06-01), Doriot
patent: 2950441 (1960-08-01), Spencer
patent: 3491207 (1970-01-01), Birck
patent: 3546702 (1970-12-01), Kurth
patent: 3569623 (1971-03-01), Schnitzius
patent: 3577202 (1971-05-01), Brightman

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