NONLINEAR REFERENCE SIGNAL PROCESSING FOR ECHO SUPPRESSION
First Claim
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1. A signal processing apparatus comprising:
- an input transformer and a spectral bander to accept samples of one or more input signals to form a banded frequency-domain amplitude metric of the one or more input signals for a plurality of spectral bands;
a reference signal path to accept one or more reference signals and to form a banded frequency-domain amplitude metric of an echo reference signal representing the one or more reference signals, wherein the reference signal path includes a nonlinear element, such that the banded frequency-domain amplitude metric is of a nonlinearly distorted version of the one or more reference signals;
an adaptive linear filter to accept the banded frequency-domain amplitude metric of the echo reference signal and to determine a frequency-domain amplitude metric of a predicted echo, the adaptive filter using a set of adaptively determined filter coefficients;
a filter coefficient updater coupled to the output of the input transformer and spectral bander and to the output of the adaptive linear filter, the filter coefficient updater to update the filter coefficients;
an echo suppressor coupled to the output of the input transformer and spectral bander and to the output of the adaptive linear filter, the echo suppressor to suppress echoes and to determine an echo-suppressed output signal.
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Abstract
An echo suppression system and method, and a computer-readable storage medium that is configured with instructions that when executed carry out echo suppression. Each of the system and the method includes the elements of a linear echo suppressor having a reference signal path, with a nonlinearity introduced in the reference signal path to introduce energy in spectral bands. Unlike an echo canceller, the echo suppression system and method are relatively robust to errors in the introduced nonlinearity.
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Citations
29 Claims
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1. A signal processing apparatus comprising:
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an input transformer and a spectral bander to accept samples of one or more input signals to form a banded frequency-domain amplitude metric of the one or more input signals for a plurality of spectral bands; a reference signal path to accept one or more reference signals and to form a banded frequency-domain amplitude metric of an echo reference signal representing the one or more reference signals, wherein the reference signal path includes a nonlinear element, such that the banded frequency-domain amplitude metric is of a nonlinearly distorted version of the one or more reference signals; an adaptive linear filter to accept the banded frequency-domain amplitude metric of the echo reference signal and to determine a frequency-domain amplitude metric of a predicted echo, the adaptive filter using a set of adaptively determined filter coefficients; a filter coefficient updater coupled to the output of the input transformer and spectral bander and to the output of the adaptive linear filter, the filter coefficient updater to update the filter coefficients; an echo suppressor coupled to the output of the input transformer and spectral bander and to the output of the adaptive linear filter, the echo suppressor to suppress echoes and to determine an echo-suppressed output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A signal processing apparatus comprising a processing system and configured to suppress undesired signals including echoes, the processing apparatus configured to:
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accept an input signal and an echo reference signal, the echo reference representative of one or more reference signals; determine a transformed frequency bin representation of the input signal for a plurality of frequency bins; determine a transformed banded representation of an amplitude metric of the input signal for a plurality of spectral bands by spectral banding; determine a transformed banded representation of an amplitude metric of the reference signal via a reference signal path, wherein the reference signal path includes a nonlinear element, such that the transformed banded representation is of the amplitude metric of a nonlinearly distorted version of the echo reference signal; linearly filter the transformed banded representation by a filter that uses an adaptively determined set of filter coefficients, the filtering to determine a transformed banded representation of an amplitude metric of an estimate of an echo for suppression; adaptively update the filter coefficients using the banded representation of the amplitude metric of an estimate of an echo and the banded representation of the amplitude metric of the input signal; and suppress echoes by processing the input signal according to the banded representation of the amplitude metric of an estimate of an echo and the banded representation of the amplitude metric of the input signal in order to determine an output signal. - View Dependent Claims (16)
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17. A method comprising:
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accepting an input signal and an echo reference signal; determining a transformed frequency bin representation of the input signal for a plurality of frequency bins; determining a transformed banded representation of an amplitude metric of the input signal for a plurality of spectral bands; determining a transformed banded representation of an amplitude metric of the reference signal via a reference signal path, wherein the reference signal path includes a nonlinear element, such that the transformed banded representation is of the amplitude metric of a nonlinearly distorted version of the echo reference signal; linearly filtering the transformed banded representation by a filter that uses an adaptively determined set of filter coefficients, the filtering to determine a transformed banded representation of an amplitude metric of an estimate of an echo for suppression; adaptively determining the filter coefficients using the banded representation of the amplitude metric of an estimate of an echo and the banded representation of the amplitude metric of the input signal; and suppressing echoes by processing the input signal according to the banded representation of the amplitude metric of an estimate of an echo and the banded representation of the amplitude metric of the input signal in order to determine an output signal. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A non-transitory computer-readable medium configured with instructions that when executed by at least one processor of a processing system, cause processing hardware to carry out a method comprising:
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accepting an input signal and an echo reference signal; determining a transformed frequency bin representation of the input signal for a plurality of frequency bins; determining a transformed banded representation of an amplitude metric of the input signal for a plurality of spectral bands; determining a transformed banded representation of an amplitude metric of the reference signal via a reference signal path, wherein the reference signal path includes a nonlinear element, such that the transformed banded representation is of the amplitude metric of a nonlinearly distorted version of the echo reference signal; linearly filtering the transformed banded representation by a filter that uses an adaptively determined set of filter coefficients, the filtering to determine a transformed banded representation of an amplitude metric of an estimate of an echo for suppression; adaptively determining the filter coefficients using the banded representation of the amplitude metric of an estimate of an echo and the banded representation of the amplitude metric of the input signal; and suppressing echoes by processing the input signal according to the banded representation of the amplitude metric of an estimate of an echo and the banded representation of the amplitude metric of the input signal in order to determine an output signal.
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Specification