Method and system for conducting near-field source localization

• US 7,746,225 B1
• Filed: 11/30/2005
• Issued: 06/29/2010
• Est. Priority Date: 11/30/2004
• Status: Active Grant

• Current Assignee: Nanook Innovation Corporation
• Original Assignee: University of Alaska Fairbanks (University of Alaska System)
• Inventors: Szuberla, Curt A. L., Arnoult, Kenneth M. Jr., Olson, John V.
• Primary Examiner(s): Wu; Daniel
• Assistant Examiner(s): GIRMA, FEKADESELASS
• Application Number:
  US11/291,497
• Time in Patent Office: 1,672 Days
• Field of Search: None
• US Class Current: 340/539.13
• CPC Class Codes: G01S 3/8086 determining other position line of source

Abstract

Disclosed herein is a fast method that locates nearby sources based solely on the time-of-flight of a signal across an array of sensors. The time delay for signal passage between all pairs of sensors is determined using cross-correlation estimates and a vector of time delays, τ, is constructed from the results. In the noise free case, each point in the plane is associated with a unique value of the τ vector. The plane is searched for a source location by minimizing the difference between the value of τ associated with the candidate location on the plane and the value estimated from cross-correlations. The search takes place over the three dimensional space that includes two coordinates in the plane and the propagation speed. The starting point for the search is constructed from an analytic fit of circular wave fronts to groups of sensors within the array.

Claims

1. A method for determining a source location comprising:

determining, for each sensor in a sensor array, times of source signal arrivals relative to each sensor;

receiving, by the array, infrasonic signals;

applying an analytical seed method to the relative source signal arrival times;

building a simplex from the results of the analytical seed method; and

determining a location; and

determining a location using an optimization procedure.

2. The method of claim 1 wherein the analytical seed method comprises:

redefining a location and a signal arrival time of a sensor as a new origin;

determining signal speed; and

determining a source location and source time.

3. The method of claim 1 wherein the optimization procedure is a Nelder-Mead optimization.

4. The method of claim 1 wherein the analytical seed method adjusts for constant known uniform motion of a medium.

5. The method of claim 1 wherein the analytical seed method adjusts for constant unknown uniform motion of a medium.

6. The method of claim 1 wherein the source is near the array.

7. The method of claim 1 wherein the source is within the array.

8. A method for determining a source location comprising:

dividing a sensor array into at least one subarray;

determining, for each subarray and for each sensor in each subarray, times of source signal arrivals relative to each sensor in the subarray;

receiving, by the array, infrasonic signals;

applying an analytical seed method to the source signal arrival times for each subarray;

building a simplex from the results of the analytical seed method; and

determining a location using an optimization procedure.

9. The method of claim 8 wherein the analytical seed method comprises:

redefining a location and a signal arrival time of a sensor as a new origin;

determining signal speed; and

determining a source location and source time.

10. The method of claim 8 wherein the optimization procedure is a Nelder-Mead optimization.

11. The method of claim 8 wherein the analytical seed method adjusts for constant known uniform motion of a medium.

12. The method of claim 8 wherein the analytical seed method adjusts for constant unknown uniform motion of a medium.

13. The method of claim 8 wherein the source is near the array.

14. The method of claim 8 wherein the source is within the array.

15. A system for determining a source location comprising:

a sensor array comprising at least four sensors;

a computing device in communication with the sensor array wherein the computing device comprises;

a memory element;

a processor coupled to the memory element wherein the processor is configured to perform the steps of;

receiving, by the sensor array, infrasonic signals;

determining, for each sensor, times of source signal arrivals relative to each sensor in the sensor array;

applying an analytical seed method to the relative source signal arrival times;

building a simplex from the results of the analytical seed method; and

determining a source location using an optimization procedure.

16. A computer readable medium with computer readable instructions embodied thereon for determining a source location comprising:

determining, for each sensor, times of source signal arrivals relative to each sensor in a sensor array;

receiving, by the sensor array, infrasonic signals;

applying an analytical seed method to the relative source signal arrival times;

building a simplex from the results of the analytical seed method; and

determining a source location using an optimization procedure.