Method and system for monopulse radar target angle determination

• US 7,859,451 B2
• Filed: 11/18/2008
• Issued: 12/28/2010
• Est. Priority Date: 11/18/2008
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Yu, Kai-Bor, Kaup, Peter G.
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US12/273,111
• Publication Number:
  US 20100123617A1
• Time in Patent Office: 770 Days
• Field of Search: 342/149, 342/152, 342/154, 342157-158, 342/80, 342107-108, 342/113, 342/133, 342139-140, 342/146
• US Class Current: 342/149
• CPC Class Codes: G01S 13/4418 with means for eliminating radar-dependent errors in angle measurements, e.g. multipath effects

Abstract

A method for determining target angles based on data received from a monopulse radar array antenna includes receiving from a beamformer that generates beams from signals generated by the monopulse radar antenna signals having data indicative of a sum beam, an azimuth difference beam, an elevation difference beam, and a delta-delta beam; based on the received signals, determining by the processor an azimuth monopulse ratio, an elevation monopulse ratio, a first complementary monopulse ratio based on the ratio of the delta-delta beam to the delta elevation beam, and a second complementary monopulse ratio based on the ratio of the delta-delta beam to the delta azimuth beam; determining an azimuth angle by the processor based on the azimuth monopulse ratio and the first complementary monopulse ratio; determining an elevation angle by the processor based on the elevation monopulse ratio and the second complementary monopulse ratio; providing an output signal indicative of the azimuth angle; and providing an output signal indicative of the elevation angle.

Claims

1. A computer-implemented method for determining target angles based on data received from a monopulse radar array antenna, comprising the steps of:

receiving by a processor of the computer, from a beamformer that generates beams from signals generated by the monopulse radar array antenna, signals having data indicative of a sum beam, an azimuth difference beam, an elevation difference beam, and a delta-delta beam;

based on the received signals, determining by the processor an azimuth monopulse ratio, an elevation monopulse ratio, a first complementary monopulse ratio based on the ratio of the delta-delta beam to the delta elevation beam, and a second complementary monopulse ratio based on the ratio of the delta-delta beam to the delta azimuth beam;

determining an azimuth angle by the processor based on the azimuth monopulse ratio and the first complementary monopulse ratio;

determining an elevation angle by the processor based on the elevation monopulse ratio and the second complementary monopulse ratio;

providing an output signal indicative of the azimuth angle; and

providing an output signal indicative of the elevation angle.

2. The method of claim 1, wherein, in the step of determining an azimuth angle, an effective azimuth monopulse ratio is determined based on the azimuth monopulse ratio weighted by the sum beam magnitude squared and the first complementary monopulse ratio weighted by the square of the elevation difference beam magnitude.

3. The method of claim 2, wherein the determining of the effective azimuth monopulse ratio comprises weighting the azimuth monopulse ratio by a square of the sum beam magnitude and weighting the first complementary monopulse ratio by a square of the elevation difference beam magnitude.

4. The method of claim 1, wherein, in the step of determining an elevation angle, an effective elevation monopulse ratio is determined based on the elevation monopulse ratio weighted by a square of the sum beam magnitude and the second complementary monopulse ratio weighted by a square of the azimuth difference beam magnitude.

5. The method of claim 4, wherein the determining of the effective elevation monopulse ratio comprises weighting the elevation monopulse ratio by a square of the sum beam magnitude and weighting the second complementary monopulse ratio by a square of the azimuth difference beam magnitude.

6. The method of claim 1, wherein the step of determining an azimuth angle comprises determining an effective azimuth monopulse ratio based on the azimuth monopulse ratio weighted by a square of the sum beam magnitude and the first complementary monopulse ratio weighted by a square of the elevation difference beam magnitude, and determining the azimuth angle based on the determined effective azimuth monopulse ratio from a table correlating monopulse ratios and azimuth angles;

and the step of determining an elevation angle comprises determining an effective elevation monopulse ratio based on the elevation monopulse ratio weighted by a square of the sum beam magnitude and the second complementary monopulse ratio weighted by a square of the azimuth difference beam magnitude; and

determining the elevation angle based on the determination effective elevation monopulse ratio from a table correlating monopulse ratios and elevation angles.

7. A system for determining target angles based on data received from a monopulse radar array antenna, comprising;

a memory device;

a processor coupled to the memory device, the processor adapted to;

receive from a beamformer that generates beams from signals generated by the monopulse radar array antenna, signals having data indicative of a sum beam, an azimuth difference beam, an elevation difference beam, and a delta-delta beam;

based on the received signals, determine an azimuth monopulse ratio, an elevation monopulse ratio, a first complementary monopulse ratio based on the ratio of the delta-delta beam to the delta elevation beam, and a second complementary monopulse ratio based on the ratio of the delta-delta beam to the delta azimuth beam;

determine an azimuth angle based on the azimuth monopulse ratio and the first complementary monopulse ratio;

determine an elevation angle based on the elevation monopulse ratio and the second complementary monopulse ratio;

provide an output signal indicative of the azimuth angle; and

provide an output signal indicative of the elevation angle.

8. The system of claim 7, wherein the processor is further adapted to determine, in determining an azimuth angle, an effective azimuth monopulse ratio based on the azimuth monopulse ratio weighted by a square of the sum beam magnitude and the first complementary monopulse ratio weighted by a square of the elevation difference beam magnitude.

9. The system of claim 8, wherein the processor is further adapted to weight, in determining the effective azimuth monopulse ratio, the azimuth monopulse ratio by a square of the sum beam magnitude and the first complementary monopulse ratio by a square of the elevation difference beam magnitude.

10. The system of claim 7, wherein the processor is further adapted to determine, in determining an elevation angle, an effective elevation monopulse ratio based on the elevation monopulse ratio weighted by a square of the sum beam magnitude and the second complementary monopulse ratio weighted by a square of the azimuth difference beam magnitude.

11. The system of claim 10, wherein the processor is further adapted to weight, in determining the effective elevation monopulse ratio, the elevation monopulse ratio by a square of the sum beam magnitude and the second complementary monopulse ratio by a square of the azimuth difference beam magnitude.

12. The system of claim 7, wherein the processor is further adapted to determine, in determining an azimuth angle, an effective azimuth monopulse ratio based on the azimuth monopulse ratio weighted by a square of the sum beam magnitude and the first complementary monopulse ratio weighted by a square of the elevation difference beam magnitude, and to determine the azimuth angle based on the determined effective azimuth monopulse ratio from a table correlating monopulse ratios and azimuth angles;

and, in determining an elevation angle, to determine an effective elevation monopulse ratio based on the elevation monopulse ratio weighted by a square of the sum beam magnitude and the second complementary monopulse ratio weighted by a square of the azimuth difference beam magnitude; and

to determine the elevation angle based on the determined effective elevation monopulse ratio from a table correlating monopulse ratios and elevation angles.

13. A method for determining target angles based on data received from a monopulse radar array antenna having a plurality of elements comprising the steps of:

forming by a beamformer based on signals generated by the monopulse rectangular radar array antenna signals having data indicative of a sum beam, an azimuth difference beam, an elevation difference beam, and a delta-delta beam;

based on the received signals, determining by the processor an azimuth monopulse ratio, an elevation monopulse ratio, a first complementary monopulse ratio based on the ratio of the delta-delta beam to the delta elevation beam, and a second complementary monopulse ratio based on the ratio of the delta-delta beam to the delta azimuth beam;

determining an azimuth angle by the processor based on the azimuth monopulse ratio and the first complementary monopulse ratio;

determining an elevation angle by the processor based on the elevation monopulse ratio and the second complementary monopulse ratio;

providing an output signal indicative of the azimuth angle; and

providing an output signal indicative of the elevation angle.

14. The method of claim 13, wherein the step of forming comprises determining a sum of the element voltages for each column of elements and determining a difference of the element voltages for each column to determine column beams, and determining a row sum and a row difference based on the column beams, to obtain the monopulse beams.

15. The method of claim 14, wherein the step of forming is performed by an analog beamformer.

16. The method of claim 13, wherein the step of forming is performed by a digital beamformer.

17. The method of claim 13, further comprising the storing of the determined elevation angle and azimuth angle by the processor in a memory device.

18. The method of claim 13, further comprising the step of receiving the output signals by a display device and display of a visual indication of the azimuth angle and the elevation angle by the display device.

19. The method of claim 13, further comprising the step of comparing by the processor a magnitude of the sum beam to a threshold, and providing by the processor a target detection signal if the magnitude of the sum beam exceeds the threshold.

20. The method of claim 19, further comprising the step of terminating calculation of the azimuth angle and elevation angle if the magnitude of the sum beam is less than the threshold.