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US 4,071,713 AGranted
Telephone speech network
AssigneeNorthern Telecom Limited
InventorMevhibe Gulay Sencer
Life of this patent
Estimating the term…
Abstract
An electronic circuit, for connecting a transmitter and receiver to a telephone line. The circuit operates on very low operating voltages from the line which allows parallel operation with a conventional set on long-loop applications. In its functional form, the circuit utilizes a bridge configuration having transistors in two of its legs, driven by the transmitter output, thereby eliminating the usual bridge balancing resistors therefrom and their concomitant operating voltage drops thereacross.
Claims4
A telephone speech network for connecting a transmitter and receiver to a telephone line, comprising:
- a plurality of transistors each having their emitter-collectors effectively connected in shunt across said telephone line for providing a signal varying impedance across the line terminals of the network;
- a line powered transmit amplifier for coupling the output of said transmitter to the base of each of the plurality of transistors, the emitter-collector of one of said transistors being connected in series with the input to a line powered receive amplifier across the telephone line;
- a balancing impedance connected in shunt with the emitter-collector of said one transistor for coupling receive signal currents from said line to said receive amplifier input and in conjunction with said one transistor to control the sidetone level of the transmit signals coupled to said input;
- and
- said receive amplifier coupling the amplified received signal currents to said receiver.
2 more elements
Dependencies are inferred from the claim text.