System and method for combining displaced phase center antenna and space-time adaptive processing techniques to enhance clutter suppression in radar on moving platforms

• US 20060181451A1
• Filed: 02/14/2005
• Published: 08/17/2006
• Est. Priority Date: 02/14/2005
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Samson, John R. Jr.
• Application Number:
  US11/058,763
• Publication Number:
  US 20060181451A1
• Time in Patent Office: Days
• US Class Current: 342/160
• CPC Class Codes: G01S 13/449 Combined with MTI or Doppler processing circuits
• CPC Class Codes: G01S 13/5242 with means for platform motion or scan motion compensation, e.g. airborne MTI
• CPC Class Codes: G01S 13/5244 Adaptive clutter cancellation specially adapted for airborne MTI, G01S13/5242
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00

Abstract

A system and method are disclosed for enhancing the suppression of clutter and target detection in a radar system located on a moving platform. For example, a radar system including an MTI subsystem is located on a moving platform (e.g., ship-borne, airborne or space-based radar system) with a DPCA processing unit located nearer to the front end of the radar receiver, and a STAP processing unit located nearer to the back end. The DPCA processing unit provides gross cancellation and suppression of the received clutter signals, and the STAP processing unit provides fine tuning for the clutter suppression process. In other words, the front end DPCA processing unit removes most of the rapidly varying clutter, which gives the back end STAP processing unit a more benign clutter environment to process. As such, using a DPCA processing unit on a space-based radar platform improves system performance, because the space-based platform is relatively stable and not subject to air turbulence or wave motion. Also, using a DPCA processing unit provides independence from clutter statistics, which is important because relatively little empirical clutter data is available from space-based radar platforms. Using a STAP processing unit for clutter suppression on the space-based radar platform provides fine tuning of the suppression process.

Claims

1. A system for suppressing clutter in a radar system, comprising:

an antenna stage;

a transmitter stage, said transmitter stage coupled to said antenna stage; and

a receiver stage, said receiver stage coupled to said antenna stage, said receiver stage including;

means for coupling received signals from said antenna stage to said receiver stage;

a displaced phase center antenna processing unit connected to said means for coupling received signals from said antenna stage to said receiver stage; and

a space-time adaptive processing unit coupled to said displaced phase center antenna processing unit.

2. The system of claim 1, further comprising:

a beam-forming processing unit, an input of said beam-forming processing unit connected to an output of said displaced phase center antenna processing unit;

a Doppler processing unit, an input of said Doppler processing unit connected to an output of said beam-forming processing unit; and

a pulse compression processing unit, an input of said pulse compression processing unit connected to an output of said Doppler processing unit, and an output of said pulse compression processing unit connected to an input of said space-time adaptive processing unit.

3. The system of claim 1, wherein said means for coupling received signals from said antenna stage to said receiver stage comprises an analog-to-digital converter.

4. The system of claim 1, wherein the radar system comprises a radar system located on a moving platform.

5. The system of claim 1, wherein said antenna stage comprises a phased array.

6. The system of claim 1, wherein said antenna stage comprises an adaptive array.

7. The system of claim 1, wherein said antenna stage comprises a displaced phase center antenna means.

8. The system of claim 1, wherein said displaced phase center antenna processing unit further comprises:

a first antenna segment, said first antenna segment including a first phase center; and

a second antenna segment, said second antenna segment including a second phase center.

9. The system of claim 1, wherein said space-time adaptive processing unit further comprises:

a sample matrix creation means;

an adaptive weight computation means coupled to said sample matrix creation means; and

a beam-forming matrix multiplication means.

10. A moving target indication system for a radar receiver comprising:

means for coupling received signals from the radar receiver to the moving target indication system;

a displaced phase center antenna processing unit connected to said means for coupling received signals from the radar receiver to the moving target indication system; and

a space-time adaptive processing unit coupled to said displaced phase center antenna processing unit.

11. The moving target indication system of claim 10, further comprising:

a beam-forming processing unit, an input of said beam-forming processing unit connected to an output of said displaced phase center antenna processing unit;

a Doppler processing unit, an input of said Doppler processing unit connected to an output of said beam-forming processing unit; and

a pulse compression processing unit, an input of said pulse compression processing unit connected to an output of said Doppler processing unit, and an output of said pulse compression processing unit connected to an input of said space-time adaptive processing unit.

12. The moving target indication system of claim 10, wherein said displaced phase center antenna processing unit further comprises:

a first antenna segment, said first antenna segment including a first phase center; and

a second antenna segment, said second antenna segment including a second phase center.

13. The moving target indication system of claim 10, wherein said space-time adaptive processing unit further comprises:

a sample matrix creation means;

an adaptive weight computation means coupled to said sample matrix creation means; and

a beam-forming matrix multiplication means.

14. A method for suppressing clutter in a radar system, the method comprising the steps of:

coupling received signals from a radar receiver to a displaced phase center antenna processing unit;

processing said received signals;

coupling said processed signals from said displaced phase center antenna processing unit to a beam-forming processing unit;

performing beam-forming processing on said processed signals;

coupling said beam-forming processed signals from said beam-forming processing unit to a Doppler processing unit;

performing Doppler filtering on said beam-forming processed signals;

coupling said Doppler filtered signals from said Doppler processing unit to a pulse compression processing unit;

performing pulse compression processing on said Doppler filtered signals;

coupling said pulse compressed signals from said pulse compression processing unit to a space-time adaptive processing unit; and

performing space-time adaptive processing on said pulse compressed signals.

15. The method of claim 14, wherein the step of processing said received signals further comprises the step of algebraically subtracting a first signal received from a first phase center associated with a first antenna segment from a second signal received from a second phase center associated with a second antenna segment.

16. The method of claim 14, wherein the step of performing said space-time adaptive processing further comprises the steps of:

creating a sample matrix;

computing a plurality of adaptive weights for a plurality of samples in said sample matrix; and

multiplying said plurality of adaptive weights with a signal comprising a form of said samples in said sample matrix.

17. The method of claim 14, further comprising the step of determining a target threshold value and constant false alarm rate for said space-time adaptive processed signal.

18. The method of claim 14, wherein the steps are performed by a coherent moving target indication processing system.

19. The method of claim 14, wherein the radar system is located on a moving platform.

20. The method of claim 14, wherein the steps of processing the received signals and performing space-time adaptive processing are performed by a displaced phase center antenna processing unit and space-time adaptive processing unit, respectively.