Wake filter for false alarm suppression and tracking

• US 5,995,038 A
• Filed: 01/26/1998
• Issued: 11/30/1999
• Est. Priority Date: 01/26/1998
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Ikizyan, Ike A.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/013,800
• Time in Patent Office: 673 Days
• Field of Search: 342/96, 342/89, 342/90, 342/91, 342/93, 342/159, 342/160, 342/162
• US Class Current: 342/91
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 7/2927 by deriving and controlling a threshold value

Abstract

A processing technique suitable for use with a search radar system which minimizes the false detection of targets. Rather than rely on a predetermined target trajectory, such as a straight line trajectory in range time space, the processing technique in accordance with the present invention is not based on a target dynamics model. The system in accordance with the present invention relies on past detections and assigns a confidence level to detections which are in the wake of a previous detection. A wake function is used to determine the amount by which each detection recursively accrues confidence based on a limited record of past detections. A detection is declared when the confidence level exceeds a predetermined threshold. As detections are encountered in range time space, such detections are used to form wakes based on the wake function which are used to assign confidence levels for future detections.

Claims

1. A system for optimizing detection in a radar system;

means for storing detections of targets;

means for assigning a confidence boost to such detections as a predetermined function of previous detections to generate new event signals;

means for comparing said new event signals with a predetermined threshold and indicating a true detection when said new event signals exceeds said threshold.

2. The system as recited in claim 1, wherein said predetermined function is a non-linear function.

3. The system as recited in claim 2, wherein said non-linear function is a function of one or more indices.

4. The system as recited in claim 3, wherein one of said indices is range bin b_j.

5. The system as recited in claim 3 wherein one of said indices is time t_j.

6. The system as recited in claim 2, wherein said function is a wake function.

8. The process as recited in claim 1, wherein said predetermined function is a non-linear function.

9. The process as recited in claim 2, wherein said non-linear function is a function of one or more indices.

10. The process as recited in claim 3, wherein one of said indices is range bin b_j.

11. The process as recited in claim 3 wherein one of said indices is time t_j.

12. The process as recited in claim 2, wherein said function is a wake function.

7. A process for optimizing detection in a radar process, comprising the steps of:

(a) storing detection of targets;

(b) assigning a confidence boost to such detections as a predetermined function of previous detections to generate new event signals;

(c) comparing said new event signals with a predetermined threshold and indicating true detection when said new event exceeds said threshold.

13. A system for minimizing false detections of a radar system, the system comprising:

a random access memory (RAM) for storing range bin b_j and time t_j indices for new detection signals;

a read only memory for storing a non-linear function accessible by one or more of said indices and generating a confidence boost as a predetermined function of previous detections; and

means for adding said confidence boost to said new detection signals.

14. The system as recited in claim 13 further including means for generating an initial confidence level to each new detection signal.

15. The system as recited in claim 14, wherein said generating means includes means for comparing each new detection signal with prior detection signals.

16. The system as recited in claim 15 wherein said comparing means includes means for comparing the range bin index b_j for each new detection signal with the range bin indices b_j of previous detection signals and generating an absolute value signal for each previous detection signal.

17. The system as recited in claim 16, further including means for storing said absolute value signals and determining the maximum absolute signal for all previous detection signals currently stored in said RAM and said new detection signal.

18. The system as recited in claim 17, further including means for storing the confidence level for each new detection signal in said RAM.

19. A process for minimizing false detections of a radar system, the system comprising:

(a) storing the range bin index b_j for each new detection signal in a random access memory;

(b) comparing the range bin index b_j for each new detection signal with previously stored detection signals;

(c) determining the maximum absolute value of the difference between said new detection signal and each of said previously stored detection signals;

(d) adding a confidence boost signal to said new detection signal as a function of said maximum value.

20. The process as recited in claim 19 further including the step of adding an initial confidence signal to each new detection signal.

21. The process as recited in claim 19, further including the steps of storing said new detection signal and said confidence boost signal.

22. The process as recited in claim 21, wherein each new detection signal stored replaces the oldest detection signal stored.