METHOD AND SYSTEM FOR LOCATING SIGNAL EMITTERS USING CROSS-CORRELATION OF RECEIVED SIGNAL STRENGTHS

• US 20100134309A1
• Filed: 12/01/2008
• Published: 06/03/2010
• Est. Priority Date: 12/01/2008
• Status: Active Grant

• Current Assignee: Keysight Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Fernandez, Andrew David, Vook, Deitrich Werner, Cutler, Robert Thomas
• Granted Patent: US 9,035,762 B2
• Time in Patent Office: Days
• US Class Current: 340/686.100
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter

Abstract

A method and system for determining a location of a first device that emits a signal: provide at least three sensors separated and spaced apart from each other; at each of the sensors, receive the signal emitted by the first device; determine the received signals for each of the sensors; determine cross-correlations of the received signals for pairs of the sensors; and determine the location of the first device from the magnitudes of the cross-correlations of the received signals.

Claims

1. A method of determining a location of a first device that emits a signal, comprising:

providing at least three sensors separated and spaced apart from each other;

at each of the sensors, receiving the signal emitted by the first device;

acquiring the received signals for each of the sensors;

determining magnitudes of cross-correlations between the received signals for pairs of the sensors; and

determining the location of the first device from the magnitudes of the cross-correlations of the received signals.

2. The method of claim 1, further comprising calculating ratios of peak powers of the cross-correlations of the received signals.

3. The method of claim 1, wherein determining the location of the first device from the cross-correlations comprises:

determining cross-correlation ratios of pairs of the cross-correlations, wherein in each of the pairs of cross-correlations, a pair of sensors for a first one of the cross-correlations in the pair of cross-correlations includes a same sensor as a pair of sensors for a second one of the cross-correlations in the pair of cross-correlations;

determining peak probability curves for each of the cross-correlation ratios; and

determining the emitter location as an area where the curves intersect.

4. The method of claim 1, wherein determining the location of the first device from the cross-correlation comprises:

determining cross-correlation ratios of pairs of the cross-correlations, wherein in each of the pairs of cross-correlations, a pair of sensors for a first one of the cross-correlations in the pair of cross-correlations includes a same sensor as a pair of sensors for a second one of the cross-correlations in the pair of cross-correlations;

determining a cross-correlation ratio likelihood map for each of the cross-correlation ratios;

determining a composite likelihood map from a set comprising all of the cross-correlation ratio likelihood maps;

determining the emitter location as an area on the composite likelihood map with greatest likelihood.

5. The method of claim 1, further comprising calculating ratios of the cross-correlations at a time offset corresponding to a time difference between a point at coordinates X, Y on a two-dimensional probability plot, and a corresponding pair of sensors,

$\frac{X_{12}}{}$

τ



( x , y ) X 13 

τ



( x , y ) .

6. The method of claim 1, further comprising synchronizing the sensors to have a common sense of time.

7. The method of claim 1, further comprising applying Doppler correction to the received signals.

8. The method of claim 1, further comprising:

at each of the sensors, receiving a second signal emitted by a second device, the second signal being transmitted at a same time and on a same frequency as the signal emitted by the first device; and

determining the location of the second device from the magnitudes of the cross-correlations of the received signals.

9. The method of claim 1, wherein the signal is an acoustic signal.

10. The method of claim 1, wherein the signal is an electromagnetic signal.

11. A system for determining a location of a first device that emits a signal, the system comprising:

at least three sensors separated and spaced apart from each other, each of the sensors including a receiver adapted to receive the signal emitted by the first device and to acquire the received signals for each of the sensors;

a network connecting the sensors and adapted to communicate data from the sensors;

means for determining magnitudes of the cross-correlations of the received signals for pairs of the sensors; and

means for determining the location of the first device from the magnitudes of the cross-correlations of the received signals.

12. The system of claim 11, further comprising a processor, wherein the means for determining the magnitudes of the cross-correlations of the received signals comprises the processor.

13. The system of claim 12, wherein the means for determining the location of the first device from the magnitudes of the cross-correlations of the received signals comprises the processor.

14. The system of claim 12, wherein the processor is included in one of the sensors.

15. The system of claim 14, wherein the means for determining the location of the first device from the magnitudes of the cross-correlations of the received signals comprises the processor.

16. The system of claim 14, wherein the means for determining the location of the first device from the magnitudes of the cross-correlations of the received signals comprises a second processor external to the sensors and connected to the sensors by the network.

17. The system of claim 12, wherein the processor is external to the sensors and is connected to the sensors by the network.

18. The system of claim 17, wherein the means for determining the location of the first device from the magnitudes of the cross-correlations of the received signals comprises the processor.

19. The system of claim 11, further comprising means for calculating ratios of peak powers of the cross-correlations of the received signals.

20. The system of claim 11, wherein the means for determining the location of the first device from the cross-correlations comprises:

means for determining cross-correlation ratios of pairs of the cross-correlations, wherein in each of the pairs of cross-correlations, a pair of sensors for a first one of the cross-correlations in the pair of cross-correlations includes a same sensor as a pair of sensors for a second one of the cross-correlations in the pair of cross-correlations;

means for determining peak likelihood curves for each of the cross-correlation ratios; and

means for determining the emitter location as an area where the curves intersect.

21. The system of claim 11, wherein the means for determining the location of the first device from the cross-correlations comprises:

means for determining cross-correlation ratios of pairs of the cross-correlations, wherein in each of the pairs of cross-correlations, a pair of sensors for a first one of the cross-correlations in the pair of cross-correlations includes a same sensor as a pair of sensors for a second one of the cross-correlations in the pair of cross-correlations;

means for determining a cross-correlation ratio likelihood map for each of the cross-correlation ratios;

means for determining a composite likelihood map from a set comprising all of the cross-correlation ratio likelihood maps;

means for determining the emitter location as an area on the composite likelihood map with greatest likelihood.

22. The system of claim 11, further comprising means for calculating ratios of the cross-correlations at a time offset corresponding to a time difference between a point at coordinates X, Y on a two-dimensional likelihood plot, and a corresponding pair of sensors,

$\frac{X_{12}}{}$

τ



( x , y ) X 13 

τ



( x , y ) .