System and method for moving target detection

• US 6,697,010 B1
• Filed: 04/23/2002
• Issued: 02/24/2004
• Est. Priority Date: 04/23/2002
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Lam, Larry K.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): ALSOMIRI, ISAM A
• Application Number:
  US10/127,607
• Time in Patent Office: 672 Days
• Field of Search: 342/25, 342/107, 342/175-179, 342/184-186, 342/104, 342/114, 342/160, 382/107
• US Class Current: 342/25.00R
• CPC Class Codes: G01S 13/5242 with means for platform motion or scan motion compensation, e.g. airborne MTI
• CPC Class Codes: G01S 13/9029 specially adapted for moving target detection within a single SAR image or within multiple SAR images taken at the same time
• CPC Class Codes: G01S 13/9054 Stripmap mode
• CPC Class Codes: G01S 13/9058 Bistatic or multistatic SAR

Abstract

The present invention is a system and method for radar detection of moving targets. The radar system of the present invention has only a single transmit phase center and a single receive phase center. The method of the present invention includes radiating a set of pulses to illuminate a desired scene. The pulses are reflected off of a target and a set of return signals are received. The pulse returns are then digitized, resulting in a set of data returns. Motion compensation is then performed on the entire set of data returns. A plurality of blocks of the motion compensated data are selected that are highly overlapping in time. A plurality of images is then generated from the plurality of blocks of motion compensated data. A consecutive set of the plurality of images is then selected. Lastly, moving objects represented within the consecutive set of images are identified.

Claims

1. A method for detecting a moving target, comprising:

detecting radiation reflected off of a target or emitted by a target;

digitizing the detected radiation, resulting in a set of data returns;

applying motion compensation to the entire set of data returns;

selecting a plurality of blocks of the motion compensated data that are highly overlapping in time;

generating a plurality of images from the plurality of blocks of motion compensated data;

selecting a consecutive set of the plurality of images; and

identifying moving objects represented within the consecutive set of images.

2. The method of claim 1, further comprising:

generating a set of returns for a scene by repeatedly illuminating the scene using a single moving source and receiving a set of return signals.

3. The method of claim 1, wherein the motion compensation comprises:

compensating the returns for changes in range resulting from the relative radial motion of the source and the scene, producing a motion compensated data set.

4. The method of claim 1, wherein the radiation is detected by a single receive phase center.

5. The method of claim 4, wherein the size of the set of data returns is from about the same size to twice as large as the nominal data block size for forming a high resolution SAR image.

6. A method for detecting a moving target, the method comprising:

detecting radiation reflected off of a target or emitted by a target;

digitizing the detected radiation resulting in a set of data returns;

applying motion compensation to the entire set of data returns;

selecting a plurality of blocks of the motion compensated data that are highly overlapping in time;

generating a plurality of images from the plurality of blocks of motion compensated data;

selecting a consecutive set of the plurality of images; and

identifying moving objects represented within the consecutive set of images;

wherein the step of identifying moving objects comprises;

extracting a time series of reflection coefficients for at least some of the pixel locations of the consecutive set of images;

producing a pixel function for each pixel, thereby representing the consecutive set of images by a collection of pixel functions;

removing the linear phase component from each pixel function, producing phase compensated pixel functions;

applying a high pass filter to each phase compensated pixel function; and

integrating the output of each filtered pixel function to produce a corresponding pixel value.

7. The method of claim 6, further comprising:

selecting as possible moving objects pixels with pixel values greater than a pre-determined threshold.

8. A system for detecting moving targets, comprising:

a radar having a single receive phase center receiving radiation and generating a data set representing the received radiation;

a motion compensation element for motion compensating the entire data set;

a moving target detect element;

selecting a plurality of blocks of the motion compensated data that are highly overlapping in time,

generating a plurality of images from the plurality of blocks of motion compensated data,

identifying moving objects represented within the plurality of images.

9. A method for detecting a moving object, the method comprising:

receiving a signal from a target;

forming a first set of data based on at least information associated with the received signal;

performing a motion compensation to the entire first set of data to form a second set of motion compensated data;

forming at least a first subset of motion compensated data and a second subset of motion compensated date, the first subset of motion compensated data being a first part of the second set of motion compensated data, the second subset of motion compensated data being a second part of the second set of motion compensated data, the first subset and the second subset overlapping in time;

generating at least a first image and a second image based on at least information associated with the first subset and the second subset respectively; and

identifying a moving object based on at least information associated with the first image and the second image;

wherein

the performing motion compensation to the entire first set of data is free from dividing the first set of data into at least a third subset of data and a fourth subset of data, the third subset and the fourth subset overlapping in time.

10. The method of claim 9 wherein the performing a motion compensation to the entire first set of data is free from performing a first motion compensation to the third subset of data and performing a second motion compensation to the fourth subset of data, the first motion compensation and the second motion compensation being different.

11. The method of claim 9 wherein the first image and the second image have phase coherency in response to at least the performing motion compensation to the entire first set of data.

12. The method of claim 9 wherein the identifying a moving object based on at least information associated with the first image and the second image comprises associating a first parameter of the first image and a second parameter of the second image, wherein the first parameter is based on at least a first phase of the first image, and the second parameter is based on at least a second phase of the second image.

13. The method of claim 12 wherein the first parameter comprises a first reflection coefficient and the second parameter comprises a second reflection coefficient, the first reflection coefficient equal to a first complex number, the second reflection coefficient equal to a second complex number.

14. The method of claim 13 wherein the associating a first parameter of the first image and a second parameter of the second image comprises forming at least a first pixel function.

15. The method of claim 14 wherein for a stationary point the first pixel function is a linear function.

16. The method of claim 14 wherein for a moving point the first pixel function is an nth-order polynomial function, n being an integer larger than one.

17. The method of claim 14 wherein the identifying a moving object is based on at least information associated with the first pixel function and information associated with phase coherency of the first image and the second image in response to at least the performing a motion compensation to the entire first set of data.

18. The method of claim 9 wherein the receiving a signal from a target is performed by only one antenna.

19. A system for detecting a moving object, the system comprising:

an antenna configured to receive a signal from a target and form a first set of data based on at least information associated to the received signal;

a motion compensation system configured to perform a motion compensation on the entire first set of data and form a second set of motion compensated data;

a moving object detection system configured to

form at least a first subset of motion compensated data and a second subset of motion compensated date, the first subset of motion compensated data being a first part of the second set of motion compensated data, the second subset of motion compensated data being a second part of the second set of motion compensated data, the first subset and the second subset overlapping in time;

generate at least a first image and a second image based on at least information associated with the first subset and the second subset respectively; and

identify a moving object based on at least information associated with the first image and the second image;

wherein

the perform a motion compensation on the entire first set of data is free from dividing the first set of data into at least a third subset of data and a fourth subset of data, the third subset and the fourth subset overlapping in time.