Echo cancellation for modems

Details Echo cancellation for modems Echo cancellation for modems

1995-11-14

1997-10-28

Zele, Krista M.

Multiplex communications

Duplex

Transmit/receive interaction control

379410, 370290, 375222, H04B 323

Patent

active

056823789

ABSTRACT:
To improve the signal to noise ratio of the receiver of a transmitting modem, the transmitting modem is equipped with the ability to cancel the far listener echo. Advantageously, doing so allows higher data rates or reduced error rates. Cancellation of the far listener echo is achieved by coupling the signal containing the in-phase, quadrature (also known as X and Y, or real and imaginary) components of the modem transmit signal to a far echo canceller that is included in the modem in addition to the far echo canceller conventionally found in modems. However, the bulk delay employed by the additional far echo canceller is arranged to be a delay of two round trips between the transmitting modem and the receiving modem rather than the conventional single round trip delay of the conventional far echo canceller.

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Bellcore Technical Committee Contribution, TR-30.3/95-11 "Listener Echo and Modem Performance", Nov. 13, 1995.

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