Globespan Virata Corporation

Globespan, Inc.

Wenye Yang

Weimin Liu

Lujing Cai

Ehud Langberg

Xiao Liu

Xueming Lin

The present invention generally relates to echo cancellation over an asymmetric transmission and receiving spectra. An apparatus is provided having a transmit path and a receive path, with an adaptive echo canceler disposed therebetween, for communicating data within a first bandwidth and a second bandwidth respectively. A first decimator is disposed between the transmit path and the echo canceler circuit and filters an incoming signal having a first sampling rate and emits a signal output at a second, reduced sampling rate. A second decimator is disposed along said receive path and filters an incoming signal and emits a signal output at a reduced sampling rate. An adder is disposed to subtract the output of the adaptive echo canceler from output of the second decimator to generate a received signal that is substantially free of echo.

System and method for echo cancellation over asymmetric spectra

Disclosed is a system and method for signal conditioning and equalization in the time domain, preferably in a discrete multi-tone (DMT) modem. The system preferably includes a processor operating according to operating logic stored on a memory although a dedicated logical circuit may be employed. The operating logic includes logic executing the function of a low pass filter having a predetermined cutoff frequency configured to process a digitized data signal having a first sample rate f , producing a filtered data signal at a second sample rate f . The operating logic further includes logic which executes the function of a time domain equalizer, the time domain equalizer being configured to process the filtered signal to shorten the impulse response of the channel while at the same time, the time domain equalizer down-samples the filtered signal from the second sample rate f , to a third sample rate f for further processing in the frequency domain.

System and method for performing time domain equalization

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Ocean, NJ, United States of America

Wenye Yang