Technique for enhanced quality high resolution 2D imaging of ground moving targets

• US 7,106,243 B2
• Filed: 07/19/2005
• Issued: 09/12/2006
• Est. Priority Date: 11/23/2004
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Rosen, Robert A., Krikorian, Kapriel V.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US11/184,694
• Publication Number:
  US 20060109162A1
• Time in Patent Office: 420 Days
• Field of Search: 342 25 R- 25 F, 342/82, 342/89, 342/90, 342159-164, 342/175, 342/176, 342/179, 342190-197
• US Class Current: 342/25.00B
• CPC Class Codes: G01S 13/9019 Auto-focussing of the SAR signals

Abstract

A radar receiver on a moving platform images a moving target and non-moving clutter using a single SAR array. The radar receiver converts the radar returns into digital radar returns and motion compensates the digital radar returns with respect to a reference, then applies further phase compensation to obtain an autofocused synthetic aperture image. A plurality of moving target pixels descriptive of the moving target are detected within the autofocused synthetic aperture image. The plurality of moving target pixels are transformed from the autofocused image to the time domain. The time domain moving target data is focused by iteratively applying a phase compensation to the time domain moving target data.

Claims

1. A radar receiver on a moving platform for imaging a moving target from radar returns from a scene containing said moving target and clutter, said radar receiver comprising:

an analog to digital converter for converting said radar returns into digital radar returns descriptive of said scene containing said moving target and said clutter;

a digital computer for performing the steps of;

motion compensating said digital radar returns with respect to a reference, said reference within said scene to obtain motion compensated data for computing a synthetic aperture image of said scene;

estimating a phase error of said clutter within said motion compensated data and compensating said motion compensated data for said phase error to obtain an autofocused synthetic aperture image, said autofocused synthetic aperture image composed of pixels;

detecting a plurality of moving target pixels descriptive of said moving target among said pixels of said autofocused synthetic aperture image;

transforming said plurality of moving target pixels from said autofocused image to a time domain moving target data;

focusing said time domain moving target data by iteratively applying a phase compensation to said time domain moving target data.

2. A radar receiver as described in claim 1 wherein said phase compensation is computed using an adaptive interpolation for rotation of said moving target.

3. A radar receiver as described in claim 2 wherein said moving target is an endoclutter target and a Space Time Adaptive Algorithm (STAP) is applied to detect said moving target pixels describing said endoclutter target.

4. A radar receiver as described in claim 3 wherein said moving target is displayed within said autofocused image.

5. A radar receiver as described in claim 2 wherein said moving target is an exoclutter target.

6. A radar receiver as described in claim 5 wherein said moving target is displayed within said autofocused image.

7. A method for operating radar receiver on a moving platform for imaging a moving target from radar returns from a scene containing said moving target and clutter, said method comprising the steps of:

converting said radar returns into digital radar returns descriptive of said scene containing said moving target and said clutter;

motion compensating said digital radar returns with respect to a reference, said reference within said scene to obtain motion compensated data for computing a synthetic aperture image of said scene;

estimating a phase error of said clutter within said motion compensated data and compensating said motion compensated data for said phase error to obtain an autofocused synthetic aperture image, said autofocused synthetic aperture image composed of pixels;

detecting a plurality of moving target pixels descriptive of said moving target among said pixels of said autofocused synthetic aperture image;

transforming said plurality of moving target pixels from said autofocused image to a time domain moving target data;

focusing said time domain moving target data by iteratively applying a phase compensation to said time domain moving target data.

8. A method as described in claim 7 wherein said phase compensation is computed using an adaptive interpolation for rotation of said moving target.

9. A method as described in claim 8 wherein said moving target is an endoclutter target and a Space Time Adaptive Algorithm (STAP) is applied to detect said moving target pixels describing said endoclutter target.

10. A method as described in claim 9 wherein said moving target is displayed within said autofocused image.

11. A method as described in claim 8 wherein said moving target is an exoclutter target.

12. A method as described in claim 11 wherein said moving target is displayed within said autofocused image.