Full polarization synthetic aperture radar automatic target detection algorithm

• US 6,750,805 B1
• Filed: 12/20/2002
• Issued: 06/15/2004
• Est. Priority Date: 12/20/2002
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Cameron, William L.
• Primary Examiner(s): LOBO, IAN J
• Application Number:
  US10/324,769
• Time in Patent Office: 543 Days
• Field of Search: 342/25, 342/90, 342/195
• US Class Current: 342/90
• CPC Class Codes: G01S 13/9076 Polarimetric features in SAR
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• CPC Class Codes: G01S 7/412 based on a comparison between measured values and known or stored values

Abstract

A method, apparatus and computer-readable medium having stored thereon instructions for automatic detection of desired targets from radar data are disclosed. For each working point in a set of radar data, from a scattering matrix derived from collected radar data, a working total radar cross section and a working asymmetry angle are calculated. The working total radar cross section and the working asymmetry angle are then evaluated to determine whether the working point should be classified as a target point or a clutter point. The method and apparatus suitably may employ a two-dimensional table of total radar cross sections and asymmetry angles previously classified as signifying target points or clutter points. Reading from the look-up table, the working point is classified as a target point or a clutter point.

Claims

1. A method for detecting targets in radar signals comprising the steps of:

calculating for a working point in a working radar data a working total radar cross section and a working asymmetry angle from a working scattering matrix;

evaluating the working total radar cross section and the working asymmetry angle to determine whether the working point should be classified as a target point or a clutter point.

2. The method of claim 1, further comprising the step of creating a look-up table from a basis radar data associating combinations of a total radar cross section and an asymmetry angle representing target points and clutter points such that the working total radar cross section and the working asymmetry angle for the working point can be looked up in the look-up table to classify the working point as a target point or a clutter point.

3. The method of claim 1, further comprising collecting working radar data for a working area of interest having a plurality of working points.

4. The method of claim 3, wherein the working radar data for the area of interest is collected using synthetic aperture radar.

5. The method of claim 1, wherein the working scattering matrix is derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from at least one of a working vertical transmit and horizontal receive scan or a working horizontal transmit and vertical receive scan.

6. The method of claim 1, wherein the working scattering matrix derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from a working vertical transmit and horizontal receive scan and a working horizontal transmit and vertical receive scan.

7. The method of claim 2, further comprising the step of generating the look-up table of the total radar cross section versus the asymmetry angle by:

calculating for a plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from a basis scattering matrix;

generating the look-up table of the total radar cross section versus the asymmetry angle for the plurality of points in the basis radar data; and

classifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points.

8. The method of claim 7, further comprising collecting the basis radar data for a representative area of interest.

9. The method of claim 8, wherein the basis radar data for the representative area of interest is collected using synthetic aperture radar.

10. The method of claim 7, further comprising calculating for the plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from the basis scattering matrix derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from at least one of a basis vertical transmit and horizontal receive scan or a basis horizontal transmit and vertical receive scan.

11. The method of claim 7, further comprising calculating for the plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from the basis scattering matrix derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole being derived from a basis vertical transmit and horizontal receive scan and a basis horizontal transmit and vertical receive scan.

12. The method of claim 7, wherein the classifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points is performed manually by comparing the basis radar data for the representative area of interest with observational data showing positions of the target points and the clutter points.

13. The method of claim 12, wherein the identifying of the target points and the clutter points in the look-up table is manually adjusted to classify predetermined clutter points.

14. A method for detecting targets in radar signals, the method comprising the steps of:

calculating for a plurality of basis points in a basis radar data a total radar cross section and an asymmetry angle from a basis scattering matrix;

generating a look-up table of the total radar cross section versus the asymmetry angle for the plurality of basis points in the basis radar data;

classifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points;

calculating for a working point in a working radar data a working total radar cross section and a working asymmetry angle from a working scattering matrix;

comparing values of the working total radar cross section and the working asymmetry angle to the look-up table; and

reading from the look-up table whether a combination of the total radar cross section corresponding with the working total radar cross section and the asymmetry angle corresponding with the working asymmetry angle is classified as a target point or a clutter point.

15. The method of claim 14, further comprising the step of collecting working radar data for a working area of interest having a plurality of working points.

16. The method of claim 15, wherein the working radar data for the area of interest is collected using synthetic aperture radar.

17. The method of claim 14, wherein the working scattering matrix is derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from at least one of a working vertical transmit and horizontal receive scan or a working horizontal transmit and vertical receive scan.

18. The method of claim 14, wherein the working scattering matrix is derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from a working vertical transmit and horizontal receive scan and a working horizontal transmit and vertical receive scan.

19. The method of claim 14, further comprising the step of collecting basis radar data for a representative area of interest.

20. The method of claim 19, wherein the basis radar data for the representative area of interest is collected using synthetic aperture radar.

21. The method of claim 14, further comprising calculating for the plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from the basis scattering matrix derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from at least one of a basis vertical transmit and horizontal receive scan or a basis horizontal transmit and vertical receive scan.

22. The method of claim 14, further comprising calculating for the plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from the basis scattering matrix derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from a basis vertical transmit and horizontal receive scan and a basis horizontal transmit and vertical receive scan.

23. The method of claim 14, wherein the classifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points is performed manually by comparing the basis radar data for the representative area of interest with observational data showing positions of the target points and the clutter points.

24. The method of claim 23, wherein the identifying of the target points and the clutter points in the look-up table is manually adjusted to classify predetermined clutter points.

25. A method of generating a look-up table to be used for detecting targets in radar signals, the method comprising the steps of:

calculating for a plurality of basis points in a basis radar data a basis total radar cross section and an asymmetry angle from a basis scattering matrix;

generating a look-up table of the total radar cross section versus the asymmetry angle for the plurality of points in the basis radar data; and

identifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points.

26. The method of claim 25, further comprising the step of collecting the basis radar data for a representative area of interest.

27. The method of claim 26, wherein the basis radar data for the representative area of interest is collected using synthetic aperture radar.

28. The method of claim 25, wherein the basis scattering matrix is derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from at least one of a basis vertical transmit and horizontal receive scan or a basis horizontal transmit and vertical receive scan.

29. The method of claim 25, wherein the basis scattering matrix is derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from a basis vertical transmit and horizontal receive scan and a basis horizontal transmit and vertical receive scan.

30. The method of claim 25, wherein the classifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points is performed manually by comparing the basis radar data for the representative area of interest with observational data showing positions of the target points and the clutter points.

31. The method of claim 30, wherein the identifying of the target points and the clutter points in the look-up table is manually adjusted to classify predetermined clutter points.

32. A system for detecting targets in radar signals comprising:

a radar transceiver operable to collect working radar data for a working area of interest;

a signal processor for calculating for at least one working point in the working radar data a working total radar cross section and a working asymmetry angle from a working scattering matrix, and determining whether the working point is classified as a target point or a clutter point.

33. The system of claim 32, further comprising a look-up table correlating a total radar cross section versus an asymmetry angle identifying combinations of the total radar cross section and the asymmetry angle representing target points and clutter points, and a comparator for reading from the look-up table whether a combination of the total radar cross section corresponding with the working total radar cross section and the asymmetry angle corresponding with the working asymmetry angle to classify the working point as a target point or a clutter point.

34. The system of claim 33, wherein the look-up table is derived from a collection of basis radar data for a representative area of interest.

35. The system of claim 33, wherein the working scattering matrix is derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from at least one of a working vertical transmit and horizontal receive scan or a working horizontal transmit and vertical receive scan.

36. The system of claim 33, wherein the working scattering matrix is derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from a working vertical transmit and horizontal receive scan and a working horizontal transmit and vertical receive scan.

37. The system of claim 34, wherein a basis scattering matrix is derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from at least one of a basis vertical transmit and horizontal receive scan or a basis horizontal transmit and vertical receive scan.

38. The system of claim 34, wherein a basis scattering matrix is derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from a basis vertical transmit and horizontal receive scan and a basis horizontal transmit and vertical receive scan.

39. The system of claim 34, wherein selected combinations of the total radar cross section and the asymmetry angle represent target points and clutter points.

40. The system of claim 33, wherein the working radar data for the representative area of interest is collected using synthetic aperture radar.

41. The system of claim 34, wherein the basis radar data for the area of interest is collected using synthetic aperture radar.

42. The system of claim 34, wherein identifications in the look-up table of the target points and the clutter points are derived manually by comparing the basis radar data for the representative area of interest with observational data showing positions of the target points and the clutter points.

43. The system of claim 34, wherein identification in the look-up table of the target points and the clutter points is manually adjusted to classify predetermined clutter points.

44. A computer readable medium having stored thereon instructions for detecting targets in radar signals, the computer readable medium having stored thereon instructions comprising:

calculating for a working point in a working radar data a working total radar cross section and a working asymmetry angle from a working scattering matrix;

evaluating the working total radar cross section and the working asymmetry angle to determine whether the working point should be classified as a target point or a clutter point.

45. The computer readable medium of claim 44, further comprising instructions for creating a look-up table associating combinations of a total radar cross section and an asymmetry angle representing target points and clutter points such that the working total radar cross section and the working asymmetry angle for the working point can be looked up in the look-up table to classify the working point as a target point or a clutter point.

46. The computer readable medium of claim 44, further comprising instructions for collecting working radar data for a working area of interest having a plurality of working points.

47. The computer readable medium of claim 44, wherein the working radar data for the area of interest is collected using synthetic aperture radar.

48. The computer readable medium of claim 44, wherein the working scattering matrix is derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from at least one of working vertical transmit and horizontal receive scan or a working horizontal transmit and vertical receive scan.

49. The computer readable medium of claim 44, wherein the working scattering matrix derived from working vertical single pole data, working horizontal single pole data, and working cross pole data, the working cross pole data being derived from a working vertical transmit and horizontal receive scan and a working horizontal transmit and vertical receive scan.

50. The method of claim 45, further comprising instructions for generating the look-up table of the total radar cross section versus the asymmetry angle by:

calculating for a plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from a basis scattering matrix;

generating the look-up table of the total radar cross section versus the asymmetry angle for the plurality of points in the basis radar data; and

classifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points.

51. The computer readable medium of claim 50, further comprising instructions for collecting basis radar data for a representative area of interest.

52. The computer readable medium of claim 51, wherein the basis radar data for the representative area of interest is collected using synthetic aperture radar.

53. The computer readable medium of claim 50, further comprising instructions for calculating for the plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from the basis scattering matrix derived from basis vertical single pole data, basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from at least one of a basis vertical transmit and horizontal receive scan or a basis horizontal transmit and vertical receive scan.

54. The computer readable medium of claim 50, further comprising instructions for calculating for the plurality of basis points in the basis radar data the total radar cross section and the asymmetry angle from the basis scattering matrix derived from a basis vertical single pole data, a basis horizontal single pole data, and basis cross pole data, the basis cross pole data being derived from a basis vertical transmit and horizontal receive scan and a basis horizontal transmit and vertical receive scan.

55. The computer readable medium of claim 50, wherein the classifying in the look-up table which combinations of the total radar cross section and the asymmetry angle represent target points and clutter points is performed manually by comparing the basis radar data for the representative area of interest with observational data showing positions of the target points and the clutter points.

56. The computer readable medium of claim 55, wherein the identifying of the target points and the clutter points in the look-up table is manually adjusted to classify predetermined clutter points.