System and method for providing step size control for subband affine projection filters for echo cancellation applications
View Patent ↗A system and method for Acoustic Echo Cancellation. The system and method include a subband affine projection filter and a variable step size controller configured to cancel an estimated echo from a near-end signal. The system and method also include a divergence detector adapted to reset the subband affine projection filter in response to determining a divergence is occurring. Additionally, the system and method include a double talk detector adapted to transmit a signal to mask an output signal when double talk is detected.
1. A device for Acoustic Echo Cancelling in communications equipment, the Acoustic Echo Cancelling device comprising:
a near end interface;
a far end interface;
an adaptive filter coupled between the near end interface and the far end interface;
a variable step size controller coupled to the adaptive filter, the variable step size controller comprising
a processor,
a computer readable medium, and
a plurality of instructions wherein at least a portion of the plurality of instructions are storable in the computer readable medium, and further wherein the plurality of instructions are configured to cause the processor to determine at least one of a step size and a regularization factor, wherein the at least one of the step size and the regularization factor is transmitted to the adaptive filter to provide an estimated echo signal; and
a divergence detector coupled to the adaptive filter, the divergence detector configured to detect divergence of the adaptive filter and to reset the adaptive filter in response to detecting divergence of the adaptive filter.
2. The device of claim 1 , the device further comprising a double talk detector coupled to the variable step size controller, the double talk detector configured to detect an occurrence of a double talk and transmit an output signal to indicate the occurrence of the double talk.
3. The device of claim 2 , the device further comprising a multiplexor coupled between the near end interface and the far end interface, the multiplexor adapted to mask an AEC output signal.
4. The device of claim 3 , wherein the output signal from the double talk detector is a double talk (DT) detected signal transmitted to an input of the multiplexor and wherein the multiplexor masks the AEC output signal in response to receiving the DT detected signal.
5. The device of claim 1 , wherein the processor determines the step size by:
computing an inverse far end correlation matrix;
updating an expectation of error correlation matrix;
updating a far end correlation matrix;
computing a plurality of variables, the plurality of variables comprising a numerator, denominator and a mean-square tap error (MSTE); and
calculating the step size based on a product of the MSTE, the numerator and the denominator.
6. The device of claim 1 , wherein the processor determines the step size by:
updating an expectation of error power;
computing a far end correlation matrix and a background noise power;
computing a mean-square tap error (MSTE); and
calculating the step size based on the MSTE, the expectation of error power and the background noise power.
7. The device of claim 1 , wherein the processor determines the regularization factor by:
computing background noise power; and
calculating the regularization factor based on the background noise power.
8. A communication device comprising:
at least one speaker configured to broadcast a far end signal;
at least one audio input configured to receive an audio sound; and
an Acoustic Echo Cancelling (AEC) apparatus, the AEC apparatus comprising:
a near end interface coupled to the at least one audio input;
a far end interface configured to receive the far end signal;
an adaptive filter coupled between the near end interface and the far end interface;
a variable step size controller coupled to adaptive filter, variable step size controller comprising
a processor,
a computer readable medium, and
a plurality of instructions wherein at least a portion of the plurality of instructions are storable in the computer readable medium, and further wherein the plurality of instructions are configured to cause the processor to determine at least one of a step size and a regularization factor, wherein said at least one of the step size and the regularization factor is transmitted to the adaptive filter to provide an estimated echo signal; and
a divergence detector coupled to the adaptive filter, the divergence detector configured to detect divergence of the adaptive filter and to reset the adaptive filter in response to detecting divergence of the adaptive filter.
9. The communication device of claim 8 , the AEC apparatus further comprising a double talk detector coupled to the variable step size controller, the double talk detector configured to detect an occurrence of a double talk and transmit an output signal to indicate the occurrence of the double talk.
10. The communication device of claim 9 , the AEC apparatus further comprising a multiplexor coupled between the near end interface and the far end interface, the multiplexor adapted to mask an AEC output signal.
11. The communication device of claim 10 , wherein the output signal from the double talk detector is a double talk (DT) detected signal transmitted to an input of the multiplexor, wherein the multiplexor masks the AEC output signal in response to receiving the DT detected signal.
12. The communication device of claim 1 , wherein the variable step size controller is configured to:
compute an inverse far end correlation matrix;
update an expectation of error correlation matrix;
update a far end correlation matrix;
compute a plurality of variables, the plurality of variables comprising a numerator, denominator and a mean-square tap error (MSTE); and
calculate the step size based on a product of the MSTE, the numerator and the denominator.
13. The communication device of claim 8 , wherein the variable step size controller is configured to:
update an expectation of error power;
compute a far end correlation matrix and a background noise power;
compute a mean-square tap error (MSTE); and
calculate the step size based on the MSTE, the expectation of error power and the background noise power.
14. The communication device of claim 8 , wherein the variable step size controller is configured to:
compute background noise power; and
calculate said regularization factor based on said background noise power.
15. A device for Acoustic Echo Cancelling in communications equipment, the Acoustic Echo Cancelling device comprising:
a near end interface coupled to an audio input device;
a far end interface configured to receive a far end signal;
an adaptive filter coupled between the near end interface and the far end interface;
a variable step size controller coupled to said adaptive filter, said variable step size controller comprising
a processor,
a computer readable medium, and
a plurality of instructions wherein at least a portion of the plurality of instructions are storable in the computer readable medium, and further wherein the plurality of instructions are configured to cause the processor to determine at least one of a step size and a regularization factor, wherein said at least one of the step size and the regularization factor is transmitted to the adaptive filter to provide an estimated echo signal;
a divergence detector coupled to the adaptive filter, the divergence detector configured to detect divergence of the adaptive filter and to reset the adaptive filter in response to detecting divergence of the adaptive filter; and
a double talk detector coupled to the variable step size controller, the double talk detector configured to detect an occurrence of a double talk and transmit an output signal to indicate the occurrence of the double talk.