Current sensing echo cancellation device

Details Current sensing echo cancellation device Current sensing echo cancellation device

2007-05-08

2007-05-08

Anderson, Matthew (Department: 2618)

Telephonic communications

Subscriber line or transmission line interface

C379S394000, C379S398000, C379S399020

Reexamination Certificate

active

10068780

ABSTRACT:
A passive echo cancellation circuit for reducing echoes on a subscriber line includes an output driver adapted to drive a downstream signal on the subscriber line. First sensing circuitry is coupled to the output driver and adapted to sense a current on the subscriber line to generate a first voltage. A balancing network is adapted to receive at least a portion of the downstream signal. Second sensing circuitry is adapted to sense a current in the portion of the downstream signal passing through the balancing network to generate a second voltage. An upstream driver is adapted to subtract the second voltage from the first voltage to generate an upstream signal. A method for canceling echoes on a subscriber line includes driving a downstream signal on the subscriber line; sensing a current on the subscriber line to generate a first voltage; providing a portion of the downstream signal to a balancing network; sensing a current in the portion of the downstream signal passing through the balancing network to generate a second voltage; and subtracting the second voltage from the first voltage to generate an upstream signal.

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