Robust constant false alarm rate (CFAR) detector for interference-plus-noise covariance matrix mismatch

Patent metadata

Field	Value
Publication number	US-11747434-B2
Application number	US-202117211253-A
Country	US
Kind code	B2
Filing date	Mar 24, 2021
Priority date	Oct 10, 2018
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

Detection of a radar target from a received radar signal includes computing a vector of filter weights dependent upon a steering vector and determining a threshold value dependent upon a designated probability of false alarm. The vector of filter weights is applied to samples of the received radar signal at a test cell, corresponding to a test range, to provide a filtered test signal and a test power of the filtered test signal is computed. The weights are also applied to samples of the received radar signal at a number of reference cells, to produce filtered reference signals. A reference power is computed from the filtered reference signals and the radar target is detected at the test range when a ratio of the test power to the reference power exceeds the threshold value.

First claim

What is claimed is:

1. A radar system for detecting a target, where the target is detected with a specified probability of false alarm, the system comprising:
a filter weight computation engine configured to compute a vector of filter weights dependent upon a steering vector and a transformation matrix;
a memory for storing the vector of filter weights;
a filter configured to produce a filtered radar signal by applying the vector of filter weights to samples of a received radar signal; and
a processor configured to:
compute a threshold value dependent upon the specified probability of false alarm;
compute a test power from a power of the filtered radar signal at a test cell corresponding to a test range;
compute a reference power from a power of the filtered radar signal at a plurality of reference cells other than the test cell; and
detect the radar target at the test range when a ratio of the test power to the reference power exceeds a threshold value.

2. The radar system of claim 1 , where the vector of filter weights is computed as a product of the steering vector with a signal transformation matrix.

3. The radar system of claim 2 , where the signal transformation matrix is computed as an inverse covariance matrix of a set of training vectors prior to the radar signal being received.

4. The radar system of claim 3 , where the inverse covariance matrix of the set of training vectors is mismatched with an inverse covariance matrix of interference and noise in the test cell.

5. The radar system of claim 1 , where the signal transformation matrix is independent of the received radar signal.

6. The radar system of claim 1 , where the processor is configured to compute the reference power as a sum of the power of the filtered radar signal at the plurality of reference cells.

7. The radar system of claim 1 , where the processor is configured to compute the reference power as an order statistic of the power of the filtered radar signal at the plurality of reference cells.

8. The radar system of claim 1 , where the processor is configured to detect the radar target at the test cell when the ratio of the test power to the reference power exceeds the threshold value by:
scaling the reference power by the threshold value to provide a scaled reference power; and
detecting the radar target when the test power is greater than the scaled reference power.

Assignees

• US Govt as represented by Secretary of Air Force
• Us Air Force

Inventors

• Raghavan Ramachandran S

Classifications

• G01S7/023 Primary

  Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques (auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36) · CPC title

• G01S7/414

  Discriminating targets with respect to background clutter · CPC title

• G01S13/5246

  post processors for coherent MTI discriminators, e.g. residue cancellers, CFAR after Doppler filters · CPC title

• G01S7/418

  Theoretical aspects · CPC title

• G01S13/584

  adapted for simultaneous range and velocity measurements · CPC title