System and method for detection and feature extraction in passive coherent location applications

• US 6,738,021 B2
• Filed: 05/06/2002
• Issued: 05/18/2004
• Est. Priority Date: 05/04/2001
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Benner, Robert H., Baugh, Kevin W.
• Primary Examiner(s): Phan, Dao
• Application Number:
  US10/138,508
• Publication Number:
  US 20030001778A1
• Time in Patent Office: 743 Days
• Field of Search: 342/378, 342/450, 342/451, 342/452
• US Class Current: 342/451
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals

Abstract

A system and method for detection and feature extraction in a passive coherent location system is disclosed. During a coherent processing interval, detection and feature extraction operations are performed to determine peak detections and target parameters for targets. The system forms an ambiguity surface that has ambiguity surface data or the coherent processing interval. Bins from a previous ambiguity surface are associated with the ambiguity surface data. New bins are identified for new target echoes within the ambiguity surface. Peak detections are formed from the bins. The peak detections correlate to the target echoes of the coherent processing interval. Target parameters for the targets are estimated from the peak detections.

Claims

1. A method for detecting and extracting target information during a coherent processing interval within a passive coherent location system, comprising:

forming an ambiguity surface having ambiguity surface data for said coherent processing interval;

identifying bins from a previous ambiguity surface;

associating said bins from said previous ambiguity surface with said ambiguity surface data; and

identifying new bins for new target echoes within said ambiguity surface.

2. The method of claim 1, further comprising smoothing said ambiguity surface.

3. The method of claim 1, further comprising comparing said ambiguity surface with said previous ambiguity surface.

4. The method of claim 3, further comprising scanning said ambiguity surface for said bins.

5. The method of claim 1, further comprising associating said bins from previous ambiguity surface and said new bins across targeting beams to form peak detections.

6. The method of claim 5, further comprising estimating target parameters from said peak detections.

7. The method of claim 6, further comprising editing said peak detections.

8. The method of claim 1, further comprising estimating a noise floor.

9. The method of claim 8, wherein said estimating includes determining an average power of said new bins as said noise floor.

10. A method for detecting and extracting target data for targets within a coherent processing interval in a passive coherent location system, comprising:

generating an ambiguity surface;

associating bins with said ambiguity surface;

forming peak detections from said bins and a plurality of old bins from a previous ambiguity surface, wherein said peak detections correlate to target echoes within said coherent processing interval; and

estimating target parameters from said peak detections.

11. The method of claim 10, further comprising editing said peak detections.

12. The method of claim 11, wherein said editing includes receiving peak measurement data of said peak detections.

13. The method of claim 11, wherein said editing includes filtering sidelobe peaks from said peak detections.

14. The method of claim 11, wherein said editing includes removing sidelobes from close-in targets from said peak detections.

15. The method of claim 11, wherein said editing includes removing detected blade modulation peak detections from said peak detections.

16. The method of claims 11, wherein said editing includes removing from said peak detections those peak detections from zero-Doppler cancellation effects.

17. The method of claim 10, further comprising smoothing said ambiguity surface.

18. The method of claim 10, further comprising estimating variances of said target parameters.

19. The method of claim 10, further comprising outputting detection data comprising said peak detections for said coherent processing interval.

20. The method of claim 19, wherein said outputting includes outputting to a line tracker.

21. The method of claim 19, wherein said detection data further comprises said target parameters for said peak detections.

22. A method for extracting target parameters of potential targets from ambiguity surface data of an ambiguity surface in a passive coherent location system, wherein said ambiguity surface data correlates to a coherent processing interval and with echoes of said potential targets, comprising:

retrieving a previous ambiguity surface;

comparing said ambiguity surface data with said previous ambiguity surface to identify bins associated with known targets;

updating said bins with said ambiguity surface data;

identifying new bins for new target echoes of said potential target echoes;

grouping said bins and said new bins into peak detections; and

estimating said target parameters for said potential targets from said peak detections.

23. The method of claim 22, further comprising outputting said peak detections and said target parameters.

24. A system for detecting and extracting features of potential targets from an ambiguity surface for a coherent processing interval in a passive coherent location system, comprising:

an ambiguity surface formation function for forming said ambiguity surface and generating ambiguity surface data;

a peak/noise discrimination function for identifying bins for known targets and new targets with said ambiguity surface data, said known targets being identified in a previous ambiguity surface;

a peak association function for grouping said bins to determine peak detections associated with said known and new targets;

a parameter estimation function for estimating target parameters for said known and new targets from said peak detections; and

a peak editing function for editing said peak detections.

25. The system of claim 24, wherein said peak/noise discrimination function estimates of a noise floor from an average power of said new bins.

26. The system of claim 24, further comprising a variance calculation function for defining a variance for said target parameters.

27. The system of claim 24, further comprising an output including said peak detections and said target parameters.

28. The system of claim 24, further comprising an ambiguity surface smoothing function for smoothing said ambiguity surface.

29. The system of claim 28, wherein said ambiguity surface smoothing function is enabled by a smoothing switch between said ambiguity surface smoothing function and said ambiguity surface formation function.

30. The system of claim 24, wherein said peak editing function includes a sidelobe peak detection filter.

31. The system of claim 24, wherein said peak editing function includes a root-mean-squared bandwidth defined peak detection exclusion function.

32. The system of claim 31, wherein said root-mean-squared bandwidth defined peak detection exclusion function defines a threshold such that a peak detection below said threshold is excluded.

33. The system of claim 24, wherein said peak editing function includes a close-in target thresholding function.

34. The system of claim 24, wherein said peak editing function includes a blade modulation induced peak editor.

35. The system of claim 24, wherein said peak editing function includes a peak detection zero-Doppler exclusion function.

36. The system of claim 24, wherein said peak editing function includes at least one function to edit said peak detections and at least one switch to enable said at least one function.

37. The system of claim 24, wherein said peak editing function includes at least one filter to edit said peak detections and at least one switch to enable said at least one filter.

38. The system of claim 24, further comprising a strong target cancellation function to cancel strong target peak detections.

39. The system of claim 38, wherein said strong target cancellation function is enabled by a strong target cancellation switch.

40. The system of claim 24, wherein said ambiguity surface formation receives ambiguity function data correlating to said ambiguity surface.

41. A method for detecting and extracting features for targets identified by a passive coherent location system, comprising:

associating bins with ambiguity surface data and one or more old bins from a previous ambiguity surface; and

forming peak detections from said associated bins.

42. The method of claim 41, further comprising estimating target parameters from said peak detections.

43. The method of claim 42, further comprising calculating variances for said target parameters from said peak detections.

44. The method of claim 41, further comprising editing said peak detections with at least one filter.

45. The method of claim 41, further comprising editing said peak detections with at least one editing function.

46. The method of claim 41, further comprising forming an ambiguity surface containing said ambiguity surface data.

47. The method of claim 46, further comprising smoothing said ambiguity surface to remove irregularities from said ambiguity surface.

48. A passive coherent location radar system having a detection and feature extraction processing sub-system to detect targets and determine target parameters from ambiguity surface data of an ambiguity surface, comprising:

a peak/noise discriminator to compare previous ambiguity surface data to said ambiguity surface data and to update bins correlating to said previous ambiguity surface data;

new bins identified by said peak/noise discriminator for new target echoes within said ambiguity surface;

a peak associator to group said bins and said new bins identified by said peak/noise discriminator to form peak detections correlating to said targets; and

a parameter estimator to estimate said target parameters from said peak detections.

49. The passive coherent location radar system of claim 48, further comprising a peak editor to edit said peak detections.

50. The passive coherent location radar system of claim 48, further comprising an ambiguity surface former to form said ambiguity surface.

51. The passive coherent location radar system of claim 50, further comprising an ambiguity surface smoother to remove irregularities from said ambiguity surface.

52. A system for detecting and extracting target information during a coherent processing interval within a passive coherent location system, comprising:

means for forming an ambiguity surface having ambiguity surface data for said coherent processing interval;

means for identifying bins from a previous ambiguity surface;

means for associating said bins from said previous ambiguity surface with said ambiguity surface data; and

means for identifying new bins for new target echoes within said ambiguity surface.

53. A computer program product comprising a computer useable medium having computer readable code embodied therein for detecting and extracting target information during a coherent processing interval within a passive coherent location system, the computer program product adapted when run on a computer to execute steps, including:

forming an ambiguity surface having ambiguity surface data for said coherent processing interval;

identifying bins from a previous ambiguity surface;

associating said bins from said previous ambiguity surface with said ambiguity surface data; and

identifying new bins for new target echoes within said ambiguity surface.

54. A system for detecting and extracting target data for targets within a coherent processing interval in a passive coherent location system, comprising:

means for generating an ambiguity surface;

means for associating bins with said ambiguity surface;

means for forming peak detections from said bins and a plurality of old bins from a previous ambiguity surface wherein said peak detections correlate to target echoes within said coherent processing interval; and

means for estimating target parameters from said peak detections.

55. A computer program product comprising a computer useable medium having computer readable code embodied therein for detecting and extracting target data for targets within a coherent processing interval in a passive coherent location system, the computer program product adapted when run on a computer to execute steps, including:

generating an ambiguity surface;

associating bins with said ambiguity surface;

forming peak detections from said bins and a plurality of old bins from a previous ambiguity surface, wherein said peak detections correlate to target echoes within said coherent processing interval; and

estimating target parameters from said peak detections.

56. A system for detecting and extracting features for targets identified by a passive coherent location system, comprising:

means for associating bins with ambiguity surface data and one or more old bins from a previous ambiguity surface; and

means for forming peak detections from said associated bins.

57. A computer program product comprising a computer useable medium having computer readable code embodied therein for detecting and extracting features for targets identified by a passive coherent location system, the computer program product adapted when run on a computer to execute steps, including:

associating bins with ambiguity surface data and one or more old bins from a previous ambiguity surface;

; and

forming peak detections from said associated bins.