Method and system for developing and using an image reconstruction algorithm for detecting and imaging moving targets

• US 7,456,780 B1
• Filed: 07/26/2006
• Issued: 11/25/2008
• Est. Priority Date: 07/26/2006
• Status: Active Grant

• Current Assignee: Leidos, Inc. (Leidos Holdings, Inc.)
• Original Assignee: Science Applications International Corporation
• Inventors: Garren, David Alan
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US11/492,902
• Time in Patent Office: 853 Days
• Field of Search: 342/25.R, 342 25 A- 25 F, 342/115, 342159-162, 342/179, 342/180, 342/191, 342194-197
• US Class Current: 342/25.00A
• CPC Class Codes: G01S 13/9011 with frequency domain processing of the SAR signals in azimuth G01S13/9005 takes precedence
• CPC Class Codes: G01S 13/9019 Auto-focussing of the SAR signals
• CPC Class Codes: G01S 13/904 SAR modes
• CPC Class Codes: G01S 13/9064 Inverse SAR [ISAR]
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

Image reconstruction approaches that use standard Cartesian-sampled, frequency-domain SAR data, which can be collected by a platform with a single radar antenna, together with its associated metadata as the input and generate an output comprised of a set of images that show the directions of moving targets, estimates of their motions, and focused images of these moving targets.

Claims

1. A process for detecting a moving target and reconstructing a scene with a moving target from scattering data, said process comprising:

collecting an image of a scene, the image containing scattering data from the scene representing

(a) stationary scatterer reflection data and

(b) moving scatterer reflection data;

decomposing said scattering data into a plurality of subsets of scattering data;

choosing a plurality of candidate motions;

forming for each pairwise combination of each said subset of scattering data with each said candidate motion a target-focused subimage, wherein said target-focused subimage is focused according to said candidate motion;

for each said candidate motion, using a plurality of said target-focused subimages focused according to said candidate motion to form joint balanced estimates of (1) a focused subimage containing only scatterers moving with said candidate motion and (2) a defocused image containing only stationary scatterers;

for each said candidate motion using said estimate of the focused subimage containing only scatterers moving with said candidate motion and said estimate of the defocused image containing only stationary scatterers to make a binary decision with regard to the presence or absence of a target moving with said candidate motion.

2. The process according to claim 1, wherein the scattering data is two-dimensional, Cartesian-sampled, complex-valued, spatial frequency domain data.

3. The process according to claim 2, wherein one of the two dimensions is a cross-range dimension, and decomposing said scattering data into a plurality of subsets of scattering data is in the cross-range dimension.

4. The process according to claim 1, wherein each candidate motion comprises a plurality of components.

5. The process according to claim 1, wherein the image is collected using synthetic aperture radar.

6. The process according to claim 1, wherein the scattering data are collected using a co-located transmitter and receiver.

7. The process according to claim 1, wherein the scattering data are collected using inverse synthetic aperture radar.

8. The process according to claim 1, wherein the scattering data are collected using a method wherein transmitter or receiver locations are stationary during a measurement of a reflected echo.

9. The process according to claim 1, wherein the scattering data are collected for vehicle speed detection or monitoring.

10. The process according to claim 1, wherein the scattering data are collected based upon the general principles of reflection tomography.

11. The process according to claim 1, wherein the scattering data are collected for monitoring of blood flow using medical ultrasound technology.

12. The process according to claim 1, wherein an estimate of a moving entity includes two or more components of a velocity of the entity.

13. The process according to claim 12, wherein the estimate is of blood flow using medical ultrasound technology.

14. A system for detecting a moving target and reconstructing a scene with a moving target from scattering data, said system comprising:

a radar for collecting an image of a scene, the image containing scattering data from the scene representing

(a) stationary scatterer reflection data and

(b) moving scatterer reflection data;

wherein said scattering data is decomposed into a plurality of subsets of scattering data and a plurality of candidate motions is chosen;

for each pairwise combination of each said subset of scattering data with each said candidate motion forming a target-focused subimage, wherein said target-focused subimage is focused according to said candidate motion;

for each said candidate motion, using a plurality of said target-focused subimages focused according to said candidate motion to form joint balanced estimates of (1) a focused subimage containing only scatterers moving with said candidate motion and (2) a defocused image containing only stationary scatterers;

for each said candidate motion using said estimate of the focused subimage containing only scatterers moving with said candidate motion and said estimate of the defocused image containing only stationary scatterers to make a binary decision with regard to the presence or absence of a target moving with said candidate motion.

15. The system according to claim 14 wherein the scattering data is two-dimensional, Cartesian-sampled, complex-valued, spatial frequency domain data.

16. The system according to claim 15, wherein one of the two dimensions is a cross-range dimension, and decomposing said scattering data into a plurality of subsets of scattering data is in the cross-range dimension.

17. The system according to claim 14, wherein each candidate motion comprises a plurality of components.

18. The system according to claim 14, wherein the radar is a synthetic aperture radar.

19. The system according to claim 14, wherein the scattering data is collected using a co-located transmitter and receiver.

20. The system according to claim 14, wherein the radar is an inverse synthetic aperture radar.