Adaptive echo canceller
First Claim
1. An adaptive echo canceller for suppressing an echo in an input signal by a pseudo echo, said adaptive echo canceller comprising:
- a pseudo echo generation filter having a predicted impulse response sequence of an echo path as filter coefficients thereof for generating a pseudo echo;
coefficient renewal means for adaptively renewing the filter coefficients of said pseudo echo generation filter to produce renewed filter coefficients, said coefficient renewal means includingmeans for dividing the renewed filter coefficients into a plurality of groups each having a certain number of renewed filter coefficients, andmeans for successively selecting one group with a predetermined period and carrying to a correction process with respect to the renewed filter coefficients within the selected group, the correction process correcting an accumulation of errors of renewal processes; and
means for suppressing an echo by the pseudo echo generated by said pseudo echo generation filter.
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Abstract
An adaptive echo canceller for suppressing an echo in an input signal by a pseudo echo, includes a pseudo echo generation filter having a predicted impulse response sequence of an echo path as filter coefficients thereof for generating a pseudo echo, a coefficient renewal part for adaptively renewing the filter coefficients of the pseudo echo generation filter, and a part for suppressing an echo by the pseudo echo which is generated by the pseudo echo generation filter. The coefficient renewal part includes a part for dividing renewed filter coefficients into a plurality of groups each having a certain number of renewed filter coefficents, and a part for successively selecting one group with a predetermined period and carrying out a correction process with respect to the renewed filter coefficients within the selected group, where the correction process corrects an accumulation of errors of renewal processes.
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Citations
15 Claims
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1. An adaptive echo canceller for suppressing an echo in an input signal by a pseudo echo, said adaptive echo canceller comprising:
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a pseudo echo generation filter having a predicted impulse response sequence of an echo path as filter coefficients thereof for generating a pseudo echo; coefficient renewal means for adaptively renewing the filter coefficients of said pseudo echo generation filter to produce renewed filter coefficients, said coefficient renewal means including means for dividing the renewed filter coefficients into a plurality of groups each having a certain number of renewed filter coefficients, and means for successively selecting one group with a predetermined period and carrying to a correction process with respect to the renewed filter coefficients within the selected group, the correction process correcting an accumulation of errors of renewal processes; and means for suppressing an echo by the pseudo echo generated by said pseudo echo generation filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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8. The adaptive echo canceller as claimed in claim 7,
wherein said pseudo echo generation filter has N filter coefficients, wherein said coefficient renewal means divides the N renewed filter coefficients into m groups, each group having n renewed filter coefficients such that N=m× - n, and
wherein said correction process is carried out at a rate of once every sampling period of the m sampling periods.
- n, and
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9. The adaptive echo canceller as claimed in claim 7 wherein b is a coefficient described by b=E×
- m, where E denotes an error which occurs in one truncation process.
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10. A method of adaptive echo cancellation, said method comprising the steps of:
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(a) suppressing an echo in an input signal by a pseudo echo; (b) generating the pseudo echo for said suppressing in step (a) based on filter coefficients; and (c) periodically renewing the filter coefficients used to generate the pseudo echo in step (b), wherein said renewing in step (c) includes at least the steps of; (c1) selecting filter coefficients for renewal; and (c2) correcting an accumulation of errors with respect to the filter coefficients selected for renewal in step (c1). - View Dependent Claims (11, 12, 13, 14)
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15. An adaptive echo canceller for suppressing an echo in an input signal by a pseudo echo, said adaptive echo canceller comprising:
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a pseudo echo generation filter having N filter coefficients for providing a predicted impulse response sequence of an echo path to generate a pseudo echo; coefficient renewal means for adaptively renewing the filter coefficients of said pseudo echo generation filter to produce renewed filter coefficients, said coefficient renewal means including means for dividing the renewed filter coefficients into m groups, each group having n renewed filter coefficient, such that N=m×
n, andmeans for successively selecting one group with a predetermined period and carrying out a correction process with respect to the renewed filter coefficients within the selected group, the correction process correcting an accumulation of errors of renewal processes and occurring once every m sampling periods regardless of the group to which each renewed filter coefficient belongs; and means for suppressing an echo by the pseudo echo generated by said pseudo echo generation filter.
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Specification