Processing Signals

• US 20130083832A1
• Filed: 11/30/2011
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Skype S.Ã R.L. (Microsoft Corporation)
• Inventors: Sorensen, Karsten Vandborg
• Granted Patent: US 8,891,785 B2
• Time in Patent Office: Days
• US Class Current: 375/224
• CPC Class Codes: G01S 3/14 Systems for determining direction or deviation from predetermined direction aerial arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00; combinations of different interacting aerial units for giving a desired directional characteristic H01Q21/29; aerials or aerial systems providing at least two radiation patterns H01Q25/00
• CPC Class Codes: G01S 3/805 using adjustment of real or effective orientation of directivity characteristics of a transducer or transducer system to give a desired condition of signal derived from that transducer or transducer system, e.g. to give a maximum or minimum signal
• CPC Class Codes: G01S 3/86 with means for eliminating undesired waves, e.g. disturbing noises
• CPC Class Codes: G10L 2021/02166 Microphone arrays; Beamforming
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

Signals are received, over a range of angles, at an input of a device. The signals include a primary signal with a principal direction of arrival and an interfering signal with a respective interfering direction of arrival at the input. Measurements are determined for the received signals over the range of angles. Each measurement relates to a particular angle and indicating the energy of the received signals which are received from the particular angle. For each angle over the range of angles, a value is removed from the measurement for that angle, the value being based on the minimum of: (i) the energy of the measurement for that angle, and (ii) the energy of a corresponding measurement for a corresponding angle mirrored around the principal direction of arrival, whereby the remaining values of the plurality of measurements are indicative of said at least one interfering direction of arrival.

Claims

1. A method of processing signals at a device, the method comprising:

receiving signals, over a range of angles, at an input of the device, the signals including a primary signal received with a principal direction of arrival at the input and at least one interfering signal received with a respective at least one interfering direction of arrival at the input;

determining a plurality of measurements for the received signals over the range of angles, each measurement relating to a particular angle and indicating the energy of the received signals which are received from the particular angle; and

for each angle over the range of angles, removing from the measurement for that angle a value based on the minimum of;

(i) the measurement for that angle, and (ii) a corresponding measurement for a corresponding angle mirrored around the principal direction of arrival, whereby the remaining values of the plurality of measurements are indicative of said at least one interfering direction of arrival.

2. The method of claim 1 further comprising suppressing the signals received with the at least one interfering direction of arrival as indicated by said remaining values of the measurements.

3. The method of claim 1 further comprising determining the principal direction of arrival by analyzing the received signals.

4. The method of claim 1 further comprising setting the range of angles such that the principal direction of arrival is in the middle of the range of angles.

5. The method of claim 1 wherein the step of determining a plurality of measurements comprises determining a range of beamformer outputs of beamforming means applied to the received signals when steered over the range of angles, and

wherein the step of removing a value from the measurement for each angle over the range of angles comprises removing from the beamformer output energy for that angle a value based on the minimum of:

(i) the energy of the beamformer output for that angle, and (ii) the energy of a corresponding beamformer output for a corresponding angle mirrored around the principal direction of arrival, whereby the remaining values of the plurality of beamformer outputs are indicative of said at least one interfering direction of arrival.

6. The method of claim 1 wherein the measurements are correlation measurements which indicate the correlation of the received signals as a function of the angle at which the signals are received.

7. The method of claim 1 wherein the input comprises a plurality of sensors for receiving the signals, and the method further comprises using a primary beamformer to apply beamformer coefficients to the received signals thereby applying greater levels of suppression to signals received with the at least one interfering direction of arrival than to signals received with the principal direction of arrival.

8. The method of claim 1 wherein said removing step is performed in dependence upon a determination that the primary signal has the highest power of the received signals.

9. The method of claim 1 wherein the signals are one of:

(i) audio signals, (ii) general broadband signals, (iii) general narrowband signals, (iv) radar signals, (v) sonar signals, (vi) antenna signals, (vii) radio waves and (viii) microwaves.

10. A device for processing signals, the device comprising:

an input for receiving signals over a range of angles, the signals including a primary signal received with a principal direction of arrival at the input and at least one interfering signal received with a respective at least one interfering direction of arrival at the input;

means for determining a plurality of measurements for the received signals over the range of angles, each measurement relating to a particular angle and indicating the energy of the received signals which are received from the particular angle; and

means for removing, for each angle over the range of angles, from the measurement for that angle a value based on the minimum of;

(i) the measurement for that angle, and (ii) a corresponding measurement for a corresponding angle mirrored around the principal direction of arrival, whereby the remaining values of the plurality of measurements are indicative of said at least one interfering direction of arrival.

11. The device of claim 10 further comprising means for suppressing the signals received with the at least one interfering direction of arrival as indicated by said remaining values of the plurality of measurements.

12. The device of claim 10 further comprising means for determining the principal direction of arrival by analyzing the received signals.

13. The device of claim 10 wherein the range of angles is set such that the principal direction of arrival is in the middle of the range of angles.

14. The device of claim 10 wherein the means for determining comprises beamforming means arranged to be applied to the received signals and to output a plurality of beamformer outputs when steered over the range of angles, and

wherein the means for removing comprises means for removing, for each angle over the range of angles, from the beamformer output energy for that angle a value based on the minimum of:

(i) the energy of the beamformer output for that angle, and (ii) the energy of a corresponding beamformer output for a corresponding angle mirrored around the principal direction of arrival, whereby the remaining values of the plurality of beamformer outputs are indicative of said at least one interfering direction of arrival.

15. The device of claim 14 wherein the beamforming means comprises a delay-and-add beamformer.

16. The device of claim 10 wherein the measurements are correlation measurements which indicate the correlation of the received signals as a function of the angle at which the signals are received, and wherein the determining means comprises correlation measurement means for determining said correlation measurements.

17. The device of claim 10 wherein the input comprises a plurality of sensors for receiving the signals, and wherein the device comprises a primary beamformer for applying beamformer coefficients to the received signals to thereby apply greater levels of suppression to signals received with the at least one interfering direction of arrival than to signals received with the principal direction of arrival.

18. The device of claim 17 wherein the primary beamformer comprises a Minimum Variance Distortionless Response beamformer.

19. The device of claim 10 wherein the device is a television or a computer.

20. The device of claim 10 wherein the signals are audio signals and the input means comprise a plurality of microphones for receiving the audio signals.

21. A computer program product for processing signals received over a range of angles, at an input of a device, the signals including a primary signal received with a principal direction of arrival at the input and at least one interfering signal received with a respective at least one interfering direction of arrival at the input, the computer program product being embodied on a non-transient computer-readable medium and configured so as when executed on a processor of the device to perform the steps of:

determining a plurality of measurements for the received signals over the range of angles, each measurement relating to a particular angle and indicating the energy of the received signals which are received from the particular angle; and

for each angle over the range of angles, removing from the measurement for that angle a value based on the minimum of;

(i) the measurement for that angle, and (ii) a corresponding measurement for a corresponding angle mirrored around the principal direction of arrival, whereby the remaining values of the plurality of measurements are indicative of said at least one interfering direction of arrival.

22. A device configured to process signals, the device comprising:

an input block configured to receive signals over a range of angles, the signals including a primary signal received with a principal direction of arrival at the input block and at least one interfering signal received with a respective at least one interfering direction of arrival at the input block;

a determining block configured to determine a plurality of measurements for the received signals over the range of angles, each measurement relating to a particular angle and indicating the energy of the received signals which are received from the particular angle; and

a removing block configured to remove, for each angle over the range of angles, from the measurement for that angle a value based on the minimum of;

(i) the measurement for that angle, and (ii) a corresponding measurement for a corresponding angle mirrored around the principal direction of arrival, whereby the remaining values of the plurality of measurements are indicative of said at least one interfering direction of arrival.