Echo canceller
First Claim
1. An echo cancellor for multi-channel processing, comprising:
- a plurality of channels each of which includes a subtractor for subtracting an echo replica supplied by a finite length impulse response (FIR) filter unit from a transmission signal supplied by a transmission-signal input terminal to output a residual signal to a transmission-signal output terminal;
said plurality of FIR filter units storing filter coefficients which are estimated impulse responses of echo paths and receive signals from a plurality of receive-signal input terminals to produce the echo replicas by performing convolution of the filter coefficients and the receive signals;
each of said channels further including a double-talk detection circuit for monitoring powers of the transmission signal and the receive signal from a corresponding one of said transmission and receive signal input terminals and a residual signal from a corresponding one of said subtractors to detect double-talk presence and absence thereof and to output a detection signal;
each of said channels further including a filter coefficient updating circuit for updating the filter coefficients stored in a corresponding one of said FIR filter units according to a control signal;
a sequence generator generating a sequence signal;
an adaptive-operation control unit for selecting said channels in accordance with the sequence signal from said sequence generator and on the basis of a limitation result to output a selection signal;
a plurality of AND circuits each of said AND circuits outputting the control signal produced by a logical AND of the detection signal from a corresponding one of said double-talk detection circuits and the selection signal to a corresponding one of said plurality of filter coefficient updating circuits.
1 Assignment
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Accused Products
Abstract
A counter increments a count value every given time period. An adaptive operation control unit selects channels in which adaptive operations are done from all the channels in obedience to the count value to output produced selection signals to AND circuits. Double-talk detection circuits judge the presence/absence of a double-talk state and output detection signals to the AND circuits. The AND circuits operate logical AND of the selection signals and the detection signals and output the logical AND results as control signals to filter coefficient updating circuits. The filter coefficient updating circuits update or do not update filter coefficients stored in FIR filter units according to the control signals. The FIR filter units produce echo replicas by calculating convolutions of the filter coefficients and the receive signals. Subtractors subtract the echo replicas from transmission signals to output residual signals.
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Citations
21 Claims
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1. An echo cancellor for multi-channel processing, comprising:
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a plurality of channels each of which includes a subtractor for subtracting an echo replica supplied by a finite length impulse response (FIR) filter unit from a transmission signal supplied by a transmission-signal input terminal to output a residual signal to a transmission-signal output terminal; said plurality of FIR filter units storing filter coefficients which are estimated impulse responses of echo paths and receive signals from a plurality of receive-signal input terminals to produce the echo replicas by performing convolution of the filter coefficients and the receive signals; each of said channels further including a double-talk detection circuit for monitoring powers of the transmission signal and the receive signal from a corresponding one of said transmission and receive signal input terminals and a residual signal from a corresponding one of said subtractors to detect double-talk presence and absence thereof and to output a detection signal; each of said channels further including a filter coefficient updating circuit for updating the filter coefficients stored in a corresponding one of said FIR filter units according to a control signal; a sequence generator generating a sequence signal; an adaptive-operation control unit for selecting said channels in accordance with the sequence signal from said sequence generator and on the basis of a limitation result to output a selection signal; a plurality of AND circuits each of said AND circuits outputting the control signal produced by a logical AND of the detection signal from a corresponding one of said double-talk detection circuits and the selection signal to a corresponding one of said plurality of filter coefficient updating circuits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification