Steerable beamformer

Patent metadata

Field	Value
Publication number	US-9767818-B1
Application number	US-201314024802-A
Country	US
Kind code	B1
Filing date	Sep 12, 2013
Priority date	Sep 18, 2012
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

Some of the embodiments of the present disclosure provide a device comprising: a first channel configured to receive a signal, wherein the signal comprises (i) a target signal and (ii) a background signal; a second channel configured to receive the signal a time t after the first channel receives the signal; a delay control circuit configured to iteratively determine a fractional delay to maximize a correlation coefficient between the signal on the first channel and the signal on the second channel; and an adaptive fractional delay filter in the first channel configured to adaptively align, in the digital domain, the signal on the first channel with the signal on the second channel based, at least in part, on the fractional delay.

First claim

What is claimed is:

1. A device comprising:
(i) a first wave detector, and (ii) a second wave detector, wherein the second wave detector is separated from the first wave detector by a pre-determined distance;
a first channel configured to receive, at a sampling rate, a signal from the first wave detector, wherein the signal comprises (i) a target signal and (ii) a background signal;
a second channel configured to receive, at the sampling rate, the signal from the second wave detector a time t after the first channel receives the signal, wherein the pre-determined distance by which the second wave detector is separated from the first wave detector is based, at least in part, on the sampling rate;
a delay control circuit configured to iteratively determine a fractional delay to maximize a correlation coefficient between the signal on the first channel and the signal on the second channel;
an adaptive fractional delay filter in the first channel configured to
(i) introduce the fractional delay in the signal on the first channel with respect to the signal on the second channel so as to adaptively align, in the digital domain, the signal on the first channel with the signal on the second channel based, at least in part, on the fractional delay, and
(ii) introduce an integer delay in the signal on the first channel with respect to the signal on the second channel, wherein the adaptive fractional delay filter comprises:
a first finite impulse response (FIR) filter to impose a first time delay on the signal in the first channel and to produce a first time-delayed signal;
a second FIR filter to impose a second time delay on the signal in the first channel and to produce a second time-delayed signal, wherein the first FIR filter operates in parallel with the second FIR filter, and wherein the first time-delayed signal and the second time-delayed signal are applied to the delay control circuit; and
a feedback loop circuit to iteratively apply the fractional delay to the first time-delayed signal; and

a group delay circuit in the second channel configured to compensate for the integer delay in the signal on the first channel with respect to the signal on the second channel.

2. The device of claim 1 , wherein:
the adaptive fractional delay filter comprises a Farrow Fractional Delay Filter architecture.

3. The device of claim 1 , wherein the correlation coefficient comprises a phase correlation coefficient.

4. The device of claim 1 , wherein the signal comprises an electromagnetic signal.

5. The device of claim 1 , further comprising:
an output port configured to (i) provide the signal on the first channel to a beamformer circuit, wherein the signal on the first channel is delayed by the adaptive fractional delay filter and (ii) provide the signal on the second channel to the beamformer circuit,
wherein the beamformer circuit is configured to (i) amplify the target signal and (ii) suppress the background signal.

6. The device of claim 1 , wherein:
the delay control circuit is configured to adjust the fractional delay based, at least in part, on signals generated by the adaptive fractional delay filter.

7. The device of claim 1 , wherein:
the delay control circuit is configured to iteratively determine the fractional delay based, at least in part, on the sampling rate.

8. A method comprising:
receiving, at a sampling rate, a signal from a first wave detector on a first channel, wherein the signal comprises (i) a target signal and (ii) a background signal;
a time t after the first channel receives the signal, receiving, at the sampling rate, the signal from a second wave detector on a second channel, wherein the first wave detector and the second wave detector are separated by a pre-determined distance that is based, at least in part, on the sampling rate;
in a parallel process, (i) imposing a first time delay on the signal in the first channel to produce a first time-delayed signal and (ii) imposing a second time delay on the signal in the first channel to produce a second time-delayed signal;
iteratively determining, based at least in part on the first time-delayed signal and the second time-delayed signal, a fractional delay to maximize a correlation coefficient between the signal on the first channel and the signal on the second channel;
introducing the fractional delay in the signal on the first channel with respect to the signal on the second channel via a feedback loop circuit that iteratively applies the fractional delay to the first time-delayed signal; and
adaptively aligning, in the digital domain, the signal on the first channel with the signal on the second channel based, at least in part, on the fractional delay.

9. The method of claim 8 , wherein the signal comprises an audio signal.

10. The method of claim 8 , wherein the signal comprises an electromagnetic signal.

11. The method of claim 8 , wherein adaptively aligning, in the digital domain, the signal on the first channel with the signal on the second channel is performed by a Farrow Fractional Delay Filter.

12. The method of claim 8 , further comprising:
providing (i) the signal on the first channel to a beamformer circuit, wherein the signal on the first channel is delayed by an adaptive fractional delay filter, and (ii) the signal on the second channel to the beamformer circuit;
amplifying, by the beamformer circuit, the target signal; and
suppressing, by the beamformer circuit, the background signal.

13. The method of claim 12 , the method further comprising:
adjusting the fractional delay based, at least in part, on signals generated by the adaptive fractional delay filter.

14. A system comprising:
(i) a first wave detector and (ii) a second wave detector, wherein the second wave detector is separated from the first wave detector by a pre-determined distance;
a signal source locator circuit configured to
receive, at a sampling rate, a signal from the first wave detector on a first channel, wherein the signal comprises (i) a target signal and (ii) a background signal,
receive, at the sampling rate, the signal from the second wave detector on a second channel a time t after the first channel receives the signal, wherein the pre-determined distance by which the first wave detector is separated from the second wave detector is based, at least in part, on the sampling rate,
in a parallel process, (i) impose a first time delay on the signal in the first channel to produce a first time-delayed signal and (ii) impose a second time delay on the signal in the first channel to produce a second time-delayed signal;
iteratively determine, based at least in part on the first time-delayed signal and the second time-delayed signal, a fractional delay to maximize a correlation coefficient between the signal on the first channel and the signal on the second channel;
introduce the fractional delay in the signal on the first channel with respect to the signal on the second channel via a feedback loop circuit that iteratively applies the fractional delay to the first time-delayed signal;
adaptively align, in the digital domain, the signal on the first channel with the signal on the second channel based, at least in part, on the fractional delay; and
introduce an integer delay in the signal on the first channel with respect to the signal on the second channel; and

a beamformer circuit configured to
amplify the target signal based, at least in part, on (i) the signal adaptively aligned on the first channel and (ii) the signal on the second channel, and
suppress the background signal based, at least in part, on (i) the signal delayed on the first chan

Assignees

• Marvell Int Ltd

Inventors

• Jain Kapil
• Xia Haiying

Classifications

• G10L2021/02165

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• H04S7/30

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• G10L2021/02166

  Microphone arrays; Beamforming · CPC title

• G10L21/0208 Primary

  Noise filtering · CPC title

• H04R2430/23

  Direction finding using a sum-delay beam-former · CPC title