Importance

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Abstract

An improved adaptive echo cancelling system and method is disclosed. The system and method utilizes linear code spacing and is particularly well suited for echo cancellation of full scale signals. Echo cancellation is effected by use of digital-to-analog converters functioning as a multiplier receiving first digital signals representative of a received speech waveform signal and second digital signals representative of the termination network on the line, which termination network causes and defines an echo reflection of the received signal. The output of the multiplier is summed and the sum is then subtracted from the echo components of the received signal to thus achieve echo cancellation and to produce an error signal that is utilized to continuously reduce error between the actual and estimated echo waveforms. Provision is made to inhibit error indications due to circuit generated coding noise and/or predetermined small detected errors to thereby enhance system operation.

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First Claim