Methods and apparatus for determining angle of arrival (AOA) in a radar warning receiver

• US 9,739,878 B2
• Filed: 03/25/2014
• Issued: 08/22/2017
• Est. Priority Date: 03/25/2014
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Gudim, Eric J., Wellman, William H.
• Primary Examiner(s): Sotomayor, John B
• Application Number:
  US14/224,667
• Publication Number:
  US 20160363660A1
• Time in Patent Office: 1,246 Days
• Field of Search: 342 20, 342 95- 97, 342133, 342139, 342140, 342146, 342147, 342417
• CPC Class Codes: G01S 13/4472 with means specially adapted to airborne monopulse systems clutter elimination using Doppler effect: G01S13/449
• CPC Class Codes: G01S 13/66 Radar-tracking systems; Analogous systems
• CPC Class Codes: G01S 2205/03 Airborne
• CPC Class Codes: G01S 3/26 the separate antennas having differently-oriented directivity characteristics
• CPC Class Codes: G01S 3/36 the separate antennas having differently-oriented directivity characteristics
• CPC Class Codes: G01S 5/0249 Determining position using measurements made by a non-stationary device other than the device whose position is being determined
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals

Abstract

Methods and apparatus for determining an angle of arrival in a radar warning system that uses tracking to provide a more accurate angle of arrival than conventional systems. In exemplary embodiments, angle of arrival and range are mapped from measured body angles to a 3D coordinate system where modern tracking techniques are applied to improve accuracy and stabilization of measurements, then mapped back into body angles for display.

Claims

1. A method, comprising:

receiving signals from an emitter on a plurality of antennas of a radar warning receiver system;

determining an angle of arrival of the received signals from the emitter from first and second ones of the plurality of antennas;

determining a range for the emitter from a strength of the signals from the first and second ones of the plurality of antennas;

receiving navigational information for a vehicle to which the radar warning receiver is attached, the navigational information including aircraft attitude information;

combining, using a computer processor, the aircraft attitude information with the range and the angle of arrival to determine a position of the emitter in three dimensions;

using navigation data to stabilize the three-dimensional emitter position against aircraft position changes;

applying tracking to the successive three-dimensional emitter location estimates to generate at least one track of position for the emitter;

using the at least one track when information from the radar warning receiver is not available; and

transforming the at least one track into angle of arrival data.

2. The method according to claim 1, further including using Kalman tracking.

3. The method according to claim 1, further including using Least Squares Optimum tracking.

4. The method according to claim 1, further including using Simplex tracking.

5. The method according to claim 1, further including selectively using a range value corresponding to an emitter distance no greater than a preset limit, nor greater than a horizon distance determined by aircraft altitude.

6. The method according to claim 1, further including using a tracker to process a moving emitter in three position coordinates and at least one velocity coordinate.

7. The method according to claim 1, further including using angle of elevation data to limit tracking updates to a preset limit.

8. The method according to claim 1, further including tracking in three Cartesian coordinates that correspond to the coordinate axes of the aircraft navigation system.

9. The method according to claim 1, further including estimating an altitude of the emitter to determine the three-dimensional tracking.

10. An article, comprising:

a non-transitory storage medium containing stored instructions that enable a machine to;

receive signals from an emitter on a plurality of antennas of a radar warning receiver system;

determine an angle of arrival of the received signals from the emitter from first and second ones of the plurality of antennas;

determine a range for the emitter from a strength of the signals from the first and second ones of the plurality of antennas;

receive navigational information for a vehicle to which the radar warning receiver is attached, the navigational information including aircraft attitude information;

combine the aircraft attitude information with the range and the angle of arrival to determine a position of the emitter in three dimensions;

use navigation data to stabilize the three-dimensional emitter position against aircraft position changes;

apply tracking to the successive three-dimensional emitter location estimates to generate at least one track of position for the emitter;

use the at least one track when information from the radar warning receiver is not available; and

transforming the at least one track into angle of arrival data.

11. The article according to claim 10, further including instructions for using Kalman tracking.

12. The article according to claim 10, further including instructions for selectively using a range value corresponding to an emitter distance no greater than a preset limit, nor greater than a horizon distance determined by aircraft altitude.

13. The article according to claim 10, further including instructions for using a tracker to process a moving emitter in three position coordinates and at least one velocity coordinate.

14. The article according to claim 10, further including instructions for using angle of elevation data to limit tracking updates to a preset limit.

15. The article according to claim 10, further including instructions for tracking in three Cartesian coordinates that correspond to the coordinate axes of the aircraft navigation system.

16. The article according to claim 10, further including instructions for estimating an altitude of the emitter to determine the three-dimensional tracking.

17. A system, comprising:

a plurality of antennas of a radar warning receiver system to receive signals from an emitter;

a radar warning system including a memory and a processor configured to;

determine an angle of arrival of the received signals from the emitter from first and second ones of the plurality of antennas;

determine a range for the emitter from a strength of the signals from the first and second ones of the plurality of antennas;

receive navigational information for a vehicle to which the radar warning receiver is attached, the navigational information including aircraft attitude information;

combine the aircraft attitude information with the range and the angle of arrival to determine a position of the emitter in three dimensions;

use navigation data to stabilize the three-dimensional emitter position against aircraft position changes;

apply tracking to the successive three-dimensional emitter location estimates to generate at least one track of position for the emitter;

use the at least one track when information from the radar warning receiver is not available; and

transforming the at least one track into angle of arrival data.