Importance

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Abstract

In a voice processing system employing the telephone communications network, any echo of an outgoing signal is substantially eliminated from the incoming signal by appropriately combining an appropriate version of the outgoing signal with the incoming signal so that there is destructive interference with any echo of the outgoing signal. To determine the appropriate version of the outgoing signal to be combined with the incoming signal, a brief training signal is applied to the telephone transmission line. The echo of this signal returned by the transmission line is stored and convolved with the time-inverse of the training signal to produce a function which approximates the impulse response of the transmission line. This function is thereafter used to produce the version of the outgoing signal which is combined with the incoming signal for echo cancellation. Prior to use, the above-mentioned function may be tested for suitability, and if it is found to be unsuitable, a new function may be generated by repeating the process of the invention.

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First Claim