Non-linear echo cancellation of data signals
First Claim
1. An echo cancellation circuit comprisingmeans connected to receive a first bit stream corresponding to a first transmitted multilevel data signal,means connected to receive a second transmitted data signal, said second data signal including a echo portion of said first transmitted data signal having linear and non-linear components,means for processing said first bit stream to generate an approximate echo replica of said echo portion of said second signal, said processing means includingmeans for forming a set of N linear tap output signals,means for forming a set of M-N non-linear tap output signals wherein M is greater than N but less than or equal to 2N, andlogic means for summing said linear and non-linear output signals to yield said approximate echo replica.
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Abstract
An echo cancellation circuit is disclosed for use with full-duplex data transmission systems. The echo canceller can operate in spite of time invariant non-linearities in the echo channel or in the implementation of the echo canceller itself (such as in D/A converters). The echo canceller receives an echo signal having linear and non-linear components and includes N linear tap weights for cancelling the non-linear components of that echo signal where M is greater than N but less than 2N.
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Citations
8 Claims
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1. An echo cancellation circuit comprising
means connected to receive a first bit stream corresponding to a first transmitted multilevel data signal, means connected to receive a second transmitted data signal, said second data signal including a echo portion of said first transmitted data signal having linear and non-linear components, means for processing said first bit stream to generate an approximate echo replica of said echo portion of said second signal, said processing means including means for forming a set of N linear tap output signals, means for forming a set of M-N non-linear tap output signals wherein M is greater than N but less than or equal to 2N, and logic means for summing said linear and non-linear output signals to yield said approximate echo replica.
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8. In an echo cancellation circuit, an echo cancellation method comprising the steps of:
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receiving a first bit stream corresponding to a first transmitted multilevel data signal, receiving a second transmitted data signal, said second data signal including an echo portion of said first data signal having linear and non-linear components, processing said first bit stream to generate an approximate replica of the echo signal portion of said second data signal, and subtracting said approximate echo replica from the second data signal to yield a substantially echo-free replica of the second data signal, the method further including the steps of forming a set of N linear tap output signals, forming a set of M-N non-linear tap output signals wherein M is greater than N but less than or equal to 2N, and logically summing said linear and non-linear tap output signals to yield said approximate echo replica.
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Specification