METHOD AND APPARATUS FOR THREE DIMENSIONAL WAVENUMBER-FREQUENCY ANALYSIS

• US 20140269197A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Reiner, Dane E., MacGillivray, John R., Graham, David L.
• Granted Patent: US 9,453,900 B2
• Time in Patent Office: Days
• US Class Current: 367/119
• CPC Class Codes: G01S 3/80 using ultrasonic, sonic or infrasonic waves
• CPC Class Codes: G01S 3/86 with means for eliminating undesired waves, e.g. disturbing noises

Abstract

A method and apparatus for identifying an unidentified sound source in a 3-dimensional sensor array calculates a position vector for each of a plurality of sensors in the array. A time Fourier transform is computed based on time samples from each of the sensors. A spatial Fourier transform is computed for the results of the time Fourier transform and in part on the position vectors calculated. All three dimensional components of the wavenumber of the received signal, k_x, k_y and k_z are explicitly calculated to generate spatial frequency information in all three dimensions. Direction of arrival of the received sound signal is determined in all three spatial directions providing unambiguous target localization and acoustic signature characterization.

Claims

1. A method of computing wavenumber-frequency spectra comprising:

computing a position vector from signal data received from each sensor in an array of sensors based on the sensor coordinate position on a surface defined by said array, in three orthogonal directions;

performing a Fourier transform on time data from each said sensor;

performing a spatial Fourier transform based in part on each said position vector.

2. The method of claim 1, wherein said sensor array is configured as a cylindrical array.

3. The method of claim 2, wherein said position vectors are computed according to:

4. The method of claim 1 wherein said Fourier transform on time data from each sensor is computed according to:

5. The method of claim 1 wherein said spatial Fourier transform is computed according to:

6. A sensor array for receiving wave energy data comprising:

a plurality of sensors wherein a position of each said sensor with respect to a surface defined by said sensor array defines a sensor coordinate position in three orthogonal dimensions;

a processor coupled to said sensor array said processor configured to receive said sensor coordinate position and wave energy data from each said sensor, said processor further configured to compute wavenumber frequency spectra based at least in part on said sensor coordinate positions.

8. The sensor array of claim 6, wherein computing wavenumber frequency spectra further comprises:

receiving said sensor coordinate positions for each sensor in said sensor array and computing a position vector for each said sensor;

performing a Fourier transform on time data from each said position vector; and

performing a spatial Fourier transform based at least in part on each said position vector.

9. The sensor array of claim 8, wherein computing a position vector for each said sensor is performed according to:

10. The sensor array of claim 8, wherein performing a Fourier transform on time data is according to:

11. The sensor array of claim 8, wherein performing a spatial Fourier transform is according to:

7. The sensor array of claim 7, wherein said sensor array is configured as a cylindrical sonar array.

12. A method of identifying sound sources in a three-dimensional sonar array comprising:

receiving an unidentified sound source signal via at least one of a plurality of sensors disposed on a surface defined by said three-dimensional sonar array;

defining a position vector for each of said plurality of sensors based on a coordinate position of each sensor in three dimensions;

performing a time Fourier transform on time samples received at each of said plurality of sensors;

performing a spatial Fourier transform based at least in part on the position vector of each of said plurality of sensors;

analyzing the wavenumber and frequency of said unidentified sound source to determine an acoustic signature associated with said unidentified sound; and

identifying said sound source based on said acoustic signature.

13. The method of claim 12, wherein determining said acoustic signature comprises determining a speed of propagation of said sound source.

14. The method of claim 12, wherein said unidentified sound source is self noise.

15. A sonar array for providing three dimensional sensor data comprising:

a plurality of sensors disposed on a surface of said three dimensional sonar array, said surface defining a geometric surface area;

a processor configured to;

receive data from each of said plurality of sensors;

compute a position vector for each of said plurality of sensors based on a coordinate position of each sensor in three dimensions with respect to said geometric surface area;

compute a time Fourier transform on time samples received from each sensor;

compute a spatial Fourier transform based in part on said calculated position vectors; and

output the results of said spatial Fourier transform.

16. The sonar array of claim 15, wherein said geometric surface area is cylindrical.

17. The sonar array of claim 15, wherein said position vectors are computed according to:

18. The sonar array of claim 15, where said time Fourier transform is computed according to:

19. The sonar array of claim 15, wherein said spatial Fourier transform is computed according to: