Thomas Patrick Callaghan

US Patent:

58964525, Apr 20, 1999

Filed:

May 24, 1996

Appl. No.:

8/653570

Inventors:

William Chunhung Yip - Scottsdale AZ
Thomas Nall - Crystal Lake IL
Thomas Gerard Callaghan - Phoenix AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04M 100

US Classification:

379410

Abstract:

A two-wire line and a four-wire line telephone system interface with each other through a hybrid (12). After a connection between the two and four-wire line systems is made, an echo canceler (10) provides training signals to the hybrid on the transmit path an generates echo cancellation signals on the receive path. An adaptive filter (16) is employed to provide the proper echo cancellation signals, while a controller (22) provides filter coefficients based on an error signal. The training signals include the convolution of an impulse function with a sin(x)/x function. Once the filter coefficients are determined for the particular call, the transmit path of the four-wire line system is switched in and voice data between the two systems my commence.