Systems and methods for suppressing radar sidelobes using time and spectral control

• US 8,436,766 B1
• Filed: 11/05/2010
• Issued: 05/07/2013
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Technology Service Corporation
• Original Assignee: Technology Service Corporation
• Inventors: Nunn, Carroll J.
• Primary Examiner(s): Keith, Jack W
• Assistant Examiner(s): BYTHROW, PETER M
• Application Number:
  US12/940,599
• Time in Patent Office: 914 Days
• Field of Search: 342/159, 342/192, 342/195
• US Class Current: 342/159
• CPC Class Codes: G01S 13/106 using transmission of pulses having some particular characteristics G01S13/12, G01S13/22, G01S13/24, G01S13/26, G01S13/28 and G01S13/30 take precedence
• CPC Class Codes: G01S 13/28 with time compression of received pulses
• CPC Class Codes: G01S 7/2883 using FFT processing
• CPC Class Codes: G01S 7/2921 based on data belonging to one radar period

Abstract

Methods and systems are disclosed for radar pulse compression signal processing. Methods include generating a function that quantifies radar signal characteristics and using a processor to calculate time-domain derivatives of the function in the frequency domain. Methods also include generating a function that quantifies radar signal characteristics as a sum of sidelobe levels; and using a processor to control the sidelobe levels by obtaining gradients of the function in the spectral domain.

Claims

1. A computer-implemented method of suppressing radar sidelobes in pulse compression signal processing, the method comprising:

creating an objective function that quantifies radar signal characteristics;

defining spectral and time constraints to further constrain the objective function;

converting the objective function and constraints into an unconstrained optimization problem; and

using a processor to perform a gradient descent method to solve the unconstrained optimization problem and generate an optimized radar waveform.

2. The method of claim 1, further comprising:

transmitting a modulated radar pulse from an antenna based on the optimized radar waveform.

3. The method of claim 1, further comprising:

obtaining gradients of the unconstrained optimization problem in the spectral domain.

4. A computer-implemented method of suppressing radar sidelobes in pulse compression signal processing, the method comprising:

creating an objective function that quantifies radar signal characteristics as a sum of integrated sidelobe levels of a radar pulse;

defining spectral and time constraints to further constrain the objective function;

converting the objective function and constraints into an unconstrained optimization problem using a penalty method; and

using a processor to obtain gradients of the unconstrained optimization problem in the spectral domain.

5. The method of claim 4, further comprising, using a conjugate gradient method to solve the unconstrained optimization problem, minimize the integrated sidelobe levels, and generate an optimized mismatched filter.

6. The method of claim 5, further comprising, performing signal processing of a modulated radar pulse from an antenna based on the optimized filter.

7. A system for suppressing radar sidelobes in pulse compression signal processing, the system comprising:

a memory configured to store instructions for generating an optimized radar waveform; and

a processor configured to;

receive an objective function that quantifies radar signal characteristics;

define spectral and time constraints to further constrain the objective function;

convert the objective function and constraints into an unconstrained optimization problem; and

use a gradient descent method to solve the unconstrained optimization problem and generate an optimized radar waveform.

8. The system of claim 7, further comprising:

an antenna configured to transmit a modulated radar pulse from an antenna based on the optimized radar waveform.

9. The system of claim 7, wherein the processor is further configured for obtaining gradients of the unconstrained optimization problem in the spectral domain.

10. A computer-implemented method of generating an optimized mismatched filter for a pulse compression radar system, the method comprising:

receiving spectral and time constraints that define a radar pulse;

creating an objective function that quantifies radar signal characteristics as a sum of integrated sidelobe levels of a radar pulse, based on the spectral and time constraints;

converting the objective function and constraints into an unconstrained optimization problem using a penalty method; and

using a processor to obtain gradients of the unconstrained optimization problem in the spectral domain.

11. The method of claim 10, further comprising:

using a conjugate gradient method to solve the unconstrained optimization problem, minimize the integrated sidelobe levels, and generate an optimized mismatched filter.

12. The method of claim 11, further comprising, performing signal processing of a modulated radar pulse from an antenna based on the optimized filter.

13. A computer-implemented method of radar pulse compression signal processing, the method comprising:

generating a function that quantifies radar signal characteristics; and

using a processor to calculate time-domain derivatives of the function in the frequency domain.

14. The method of claim 13, further comprising,

using a gradient descent method to solve the function and generate an optimized radar waveform.

15. The method of claim 14, further comprising:

performing signal processing of a modulated radar pulse from an antenna based on the optimized radar waveform.

16. The method of claim 13, further comprising using the time-domain derivatives to minimize the function.

17. The method of claim 13, further comprising using the time-domain derivatives to obtain waveform properties, using an iterative scheme based on the function.

18. A computer-implemented method for radar pulse compression signal processing, the method comprising:

generating a function that quantifies radar signal characteristics; and

using a processor to optimize time and spectral characteristics of the radar signal characteristics using frequency domain calculations.

19. The method of claim 18, further comprising,

using a gradient descent method to solve the function and generate an optimized radar waveform.

20. The method of claim 19, further comprising:

performing signal processing of a modulated radar pulse from an antenna based on the optimized radar waveform.

21. The method of claim 18, further comprising:

calculating time-domain derivatives of the function in the frequency domain; and

using the time-domain derivatives to minimize the function.

22. The method of claim 18, further comprising:

calculating time-domain derivatives of the function in the frequency domain; and

using the time-domain derivatives to obtain waveform properties using an iterative scheme based on the function.

23. A computer-implemented method of radar pulse compression signal processing, the method comprising:

generating a function that quantifies radar signal characteristics as a sum of sidelobe levels; and

using a processor to minimize the function by obtaining gradients of the function in the spectral domain.

24. The method of claim 23, wherein minimizing the function includes minimizing the integrated sidelobe levels.

25. The method of claim 23, further comprising,

using a gradient descent method to solve the function and generate an optimized radar waveform.

26. The method of claim 25, further comprising:

performing signal processing of a modulated radar pulse from an antenna based on the optimized radar waveform.

27. The method of claim 23, further comprising:

calculating time-domain derivatives of the function in the frequency domain; and

using the time-domain derivatives to minimize the function.

28. The method of claim 23, further comprising:

calculating time-domain derivatives of the function in the frequency domain; and

using the time-domain derivatives to obtain waveform properties using an iterative scheme that uses the function.

29. A computer-implemented method of radar pulse compression signal processing, the method comprising:

generating a function that quantifies radar signal characteristics as a sum of functions of sidelobe levels; and

using a processor to control the sidelobe levels by obtaining gradients of the function in the spectral domain.

30. The method of claim 29, further comprising,

using a gradient descent method to solve the function and generate an optimized radar waveform.

31. The method of claim 30, further comprising:

performing signal processing of a modulated radar pulse from an antenna based on the optimized radar waveform.

32. The method of claim 29, further comprising:

calculating time-domain derivatives of the function in the frequency domain; and

using the time-domain derivatives to minimize the function.

33. The method of claim 29, further comprising:

calculating time-domain derivatives of the function in the frequency domain; and

using the time-domain derivatives to obtain waveform properties using an iterative scheme that uses the function.

34. A system for suppressing radar sidelobes in pulse compression signal processing, the system comprising:

a memory configured to store instructions for generating an optimized radar waveform;

a processor configured to;

generate a function that quantifies radar signal characteristics as a sum of functions of sidelobe levels; and

control the sidelobe levels by obtaining gradients of the function in the spectral domain.