System and method for measurement domain data association in passive coherent location applications

• US 6,798,381 B2
• Filed: 05/06/2002
• Issued: 09/28/2004
• 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: Sawyer, Joseph, Benner, Robert H.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US10/138,507
• Publication Number:
  US 20030048224A1
• Time in Patent Office: 876 Days
• Field of Search: 342/450, 342/451, 342/452, 342/457
• US Class Current: 342/451
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence

Abstract

A system and method for measurement domain data association in a passive coherent location system is disclosed. According to the system and method, detection reports are received and associated with line tracks. The detection reports correlate to target signals received at the passive coherent location system. Measurements of the detection report correlate to the data of the target signals. A line track state estimation function associates new detection reports with the line tracks and estimates update states for the line tracks. A signal type is determined. Kalman filters are selected for the measurements according to the signal type. Measurement residuals are computed for the detection reports according to the Kalman filters. The detection reports are selected for association with the line tracks according to the residuals. The line tracks can be merged or terminated during updates according to specific criteria. Further, new line tracks are initialized as new targets are detected.

Claims

1. A method for associating a detection report having measurements to a line track, wherein said line track correlates to a signal transmitted from a source of opportunity, reflected from a target, and detected by a passive coherent location system, comprising:

estimating a line track state vector from said measurements using a set of Kalman filters wherein said measurements are at least partially derived by comparing said signal to a reference transmission from said source of opportunity; and

initializing said line track.

2. The method of claim 1, further comprising merging said line track with another line track associated with said target.

3. The method of claim 1, further comprising terminating said line track.

4. The method of claim 1, further comprising selecting said set of Kalman filters.

5. The method of claim 1, wherein said set of Kalman filters includes range and angle-of-arrival Kalman filters.

6. The method of claim 1, wherein said set of Kalman filters includes frequency and angle-of-arrival Kalman filters.

7. The method of claim 1, wherein said estimating includes propagating state estimates for said line track.

8. The method of claim 1, further comprising determining whether said signal is a FM signal.

9. The method of claim 1, further comprising determining whether said signal is a TV signal.

10. The method of claim 9, further comprising tracking a carrier of said TV signal.

11. The method of claim 1, further comprising updating filter states of said Kalman filters.

12. A method for associating measurement data to a line track correlating to a target, wherein a target signal is reflected from said target and is received by a passive coherent location system, comprising:

determining a signal type for said signal;

converting said measurement data to filter data according to said signal type;

selecting a set of Kalman filters for said filter data according to said signal type;

propagating said line track;

identifying a detection report for said line track according to said measurement data;

computing measurement residuals and residual variances for said detection report according to said Kalman filters; and

selecting said detection report for association with said line track according to said residuals.

13. The method of claim 12, further comprising initializing line track filter states of said line track.

14. The method of claim 13, further comprising merging said line track with another line track when a merge criteria is satisfied.

15. The method of claim 14, further comprising determining said merge criteria according to said residuals.

16. The method of claim 13, further comprising terminating said line track when a termination criteria is satisfied.

17. The method of claim 16, further comprising determining said termination criteria.

18. The method of claim 12, wherein said identifying comprises comparing a signal-to-noise ratio of said detection report to a configured threshold for said line track.

19. A system for measurement data association of detection reports to a line track within a passive coherent location system, wherein said detection reports correlate to target signals transmitted from a source of opportunity, reflected from a target, and received at said passive coherent location system, comprising:

a state estimation means to associate new detection reports with existing line tracks and to estimate update states for extending line tracks, wherein said new detection reports are at least partially derived by comparing said target signal to a reference transmission from said source of opportunity;

a line track merge means to merge line tracks;

a line track termination means to terminate line tracks according to a specified criteria; and

a line track initialization means to initiate new line tracks for unassociated detection reports.

20. The system of claim 19, further comprising configuration data accessible by said means.

21. The system of claim 19, wherein said state estimation means receives an input block comprising said detection reports.

22. The system of claim 21, wherein said detection reports comprise measurements.

23. The system of claim 22, wherein said detection reports comprise variances for said measurements.

24. The system of claim 22, wherein said measurements are used by said state estimation means in associating said detection reports.

25. The system of claim 19, wherein said state estimation means includes Kalman filters for range, frequency and angle-of-arrival.

26. The system of claim 19, further comprising an output block.

27. The system of claim 26, wherein said output block comprises line track records.

28. The system of claim 26, wherein said output block comprises measurements.

29. A method for estimating line track states with detection association in a passive coherent location system, wherein said passive coherent location system receives target signals reflected from targets, said target signals having measurement values, comprising:

identifying a set of potential detection reports, wherein said detection reports comprises measurement values;

computing measurement residuals and residual variances for said measurement values;

selecting candidate detection reports for line tracks from said set of potential detection reports according to said measurement residuals;

applying thresholds to said candidate detection reports; and

associating said candidate detection reports passing said thresholds to said line tracks.

30. The method of claim 29, wherein said applying includes computing a figure-of-merit for each of said candidate detection reports.

31. The method of claim 29, wherein said identifying includes comparing a signal-to-noise ratio for each of said set of detection reports to a configured threshold.

32. A method for associating new detection reports with existing line tracks in a passive coherent location system, comprising:

gating a detection report-line track pair;

computing a score for said detection report-line track pair; and

assigning a detection report of said detection report-line track pair to a line track of said detection report-line track pair according to said score.

33. The method of claim 32, further comprising identifying said detection report according a signal-to-noise ratio measurement.

34. The method of claim 32, further comprising selecting said detection report-line track pair.

35. A method for merging line tracks within a passive coherent location system, wherein said line tracks correlate to a target, comprising:

determining a list of line tracks and line track pairs;

calculating a measurement residual for each line track pair within said list;

determining merge criteria for said each line track pair;

comparing said measurement residual with gates correlating to said merge criteria; and

removing a line track from said each line track pair that satisfies said merge criteria.

36. The method of claim 35, wherein said removed line track is younger than another line track within said each possible line track pair.

37. The method of claim 35, wherein said removed line track has a lower initial signal-to-noise ratio than another line track within said each possible line track pair.

38. A method for terminating a line track within a passive coherent location system, wherein said line track correlates to a target signal transmitted from one or more sources of opportunity, reflected from a target, and received by said passive coherent location system, comprising:

determining a termination criteria;

monitoring said line track using comparison data from said target signal and a reference transmission from said source of opportunity; and

terminating said line track when said line track achieves said termination criteria.

39. A method for initializing new line tracks within a passive coherent location system, comprising:

determining a configuration parameter for a new line track;

selecting an initialization process according to said configuration parameter;

performing said initialization process; and

initializing a filter state of said new line track.

40. The method of claim 39, wherein said performing includes performing an automatic detection process by accumulating target echo energies in predefined detection cells correlating to said new line track.

41. The method of claim 39, wherein said performing includes performing an M out of N detection process by maturing said new line track when said new line track satisfies a predetermined criteria.