ACOUSTIC WIDE AREA AIR SURVEILLANCE SYSTEM

• US 20090257314A1
• Filed: 04/14/2008
• Published: 10/15/2009
• Est. Priority Date: 04/14/2008
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Davis, Henry H., Nielsen, Richard Ove, Balmforth, Kevin Dale
• Granted Patent: US 7,872,948 B2
• Time in Patent Office: Days
• US Class Current: 367/125
• CPC Class Codes: G01S 15/66 Sonar tracking systems
• CPC Class Codes: G01S 5/18 using ultrasonic, sonic, or infrasonic waves

Abstract

A method and apparatus for detecting an aircraft. The method is provided for wide area tracking of aircraft. An acoustic emission of the aircraft is detected from a plurality of locations. A position of the aircraft at a set of times is estimated by comparing a set of harmonically related Doppler shifted frequencies for the acoustic emission to an expected zero Doppler shifted frequency of the aircraft to form an estimated position. The position of the aircraft and a heading of the aircraft are tracked using the estimated position. The aircraft type is classified based on the corresponding set of zero Doppler frequencies at each acoustic sensor.

Claims

1. A method for wide area tracking of an aircraft, the method comprising:

detecting an acoustic emission of the aircraft from a plurality of locations;

estimating a position of the aircraft at a set of times by comparing a set of harmonically related Doppler shifted frequencies for the acoustic emission to an expected zero Doppler shifted frequency of the aircraft to form an estimated position; and

tracking the position of the aircraft and a heading of the aircraft using the estimated position.

2. The method of claim 1, wherein the estimating step comprises:

comparing the set of harmonically related Doppler shifted frequencies for the acoustic emission to the expected zero Doppler shifted frequency of the aircraft; and

comparing ratios of amplitudes of the acoustic emission from the plurality of locations.

3. The method of claim 1 further comprising:

determining an estimated velocity of the aircraft and an acoustic emission frequency at a zero-Doppler for at least one of the plurality of locations.

4. The method of claim 1, wherein the detecting step comprises:

detecting the acoustic emission of the aircraft from at least three locations.

5. The method of claim 1, wherein the tracking step comprises:

tracking the position of the aircraft position and the heading of the aircraft using the estimated position and a time-phased Doppler history.

6. The method of claim 1, wherein the detecting step comprises:

detecting the acoustic emission of the aircraft from the plurality of locations using a plurality of omni-directional sound sensors at the plurality of locations.

7. The method of claim 1 further comprising:

identifying a type of aircraft from the acoustic emission.

8. The method of claim 7, wherein the step of identifying the type of aircraft from the acoustic emission comprises:

identifying a spectrum in the acoustic emission for propeller harmonics and engine exhaust harmonics to form an identified spectrum; and

identifying the type of aircraft from the identified spectrum.

9. The method of claim 8, wherein the identifying step is performed each time a sound sensor at one of the plurality of locations detects the acoustic emission.

10. A method for monitoring an area for an aircraft, the method comprising:

monitoring a plurality of sound sensors for an acoustic emission from the aircraft in the area;

responsive to detecting the acoustic emission at a set of sound sensors within the plurality of sound sensors, comparing observed frequencies for the aircraft in the acoustic emission detected by the set of sounds sensors with a set of expected frequencies for the acoustic emission to form a comparison; and

estimating a position of the aircraft from the comparison.

11. The method of claim 10, wherein the comparing step comprises:

comparing a set of harmonically related Doppler shifted frequencies from the acoustic emission as observed by the set of sound sensors to a set of expected zero Doppler shifted frequencies for the aircraft.

12. The method of claim 10 further comprising:

responsive to detecting the acoustic emission from a sound sensor in the plurality of sounds sensors, identifying a set of changes in spectral components of the acoustic emission to form a set of identified changes;

identifying a heading of the aircraft from the set of identified changes;

identifying a Doppler shifted frequency signature from the acoustic emission to form an identified Doppler shifted frequency signature; and

identifying a set of characteristics about the aircraft from the Doppler shifted frequency signature.

13. The method of claim 10 further comprising:

identifying an unshifted Doppler frequency signature for the aircraft;

identifying the set of characteristics about the aircraft from the unshifted Doppler frequency signature.

14. The method of claim 10, further comprising:

responsive to detecting the acoustic emission at multiple sound sensors in the plurality of sound sensors, estimating a position of the aircraft from differences between the acoustic emissions detected at the multiple sound sensors.

15. The method of claim 14, wherein the estimating step comprises:

responsive to detecting the acoustic emission at the multiple sound sensors in the plurality of sound sensors, estimating the position of the aircraft from the differences between frequencies and spectrum levels in the acoustic emission detected at the multiple sound sensors.

16. The method of claim 14, wherein the estimating step comprises:

comparing a set of observed frequencies for the acoustic emission to a calculated set of frequencies for the acoustic emissions for the aircraft to form an estimated position.

17. An apparatus comprising:

a plurality of sound sensors capable of detecting an acoustic emission from an aircraft;

a data processing system in communication with the plurality of sound sensors, wherein the data processing system is capable of monitoring the plurality of sound sensors for the acoustic emission from the aircraft and estimating a position of the aircraft using sound data for the acoustic emission as detected by a set of sound sensors in the plurality of sound sensors in response to detecting the acoustic emission at the set of sound sensors.

18. The apparatus of claim 17, wherein the data processing system is capable of identifying a signature for the aircraft in a range of frequencies for the acoustic emission in response to detecting the acoustic emission at the set of sounds sensors and is capable of classifying the aircraft from the signature.

19. The apparatus of claim 17, wherein a particular sound sensor in the plurality of sound sensors detecting the acoustic emission is capable of identifying the signature for the aircraft in the range of the frequencies for the acoustic emission in response to detecting the acoustic emission.

20. The apparatus of claim 18, wherein the data processing system is capable of identifying the aircraft from the signature identified by the particular sound sensor.

21. The apparatus of claim 17, wherein the data processing system is capable of identifying a heading of the aircraft from the acoustic emission.

22. The apparatus of claim 17, wherein the plurality of sound sensors are a plurality of omni-directional microphones.