CREATING AND PROCESSING UNIVERSAL RADAR WAVEFORMS

• US 20130147658A1
• Filed: 01/17/2013
• Published: 06/13/2013
• Est. Priority Date: 08/05/2010
• Status: Active Grant

• Current Assignee: Arete Associates
• Original Assignee: Arete Associates
• Inventors: Burri, Jeremy Francis, Farris, Michael Howard, Potter, Randall Edward, Pohlman, Matthew Michael
• Granted Patent: US 8,593,338 B2
• Time in Patent Office: Days
• US Class Current: 342/202
• CPC Class Codes: G01S 13/222 using random or pseudorandom pulse repetition frequency
• CPC Class Codes: G01S 13/26 wherein the transmitted pulses use a frequency- or phase-modulated carrier wave
• CPC Class Codes: G01S 13/904 SAR modes
• CPC Class Codes: G01S 7/282 Transmitters

Abstract

A new approach to radar imaging is described herein, in which radar pulses are transmitted with an uneven sampling scheme and subsequently processed with novel algorithms to produce images of equivalent resolution and quality as standard images produced using standard synthetic aperture radar (SAR) waveforms and processing techniques. The radar data collected with these waveforms can be used to create many other useful products such as moving target indication (MTI) and high resolution terrain information (HRTI). The waveform and the correction algorithms described herein allow the algorithms of these other radar products to take advantage of the quality Doppler resolution.

Claims

1. A radar transmission system comprising:

a transmitter system configured to generate one or more radar signals; and

an antenna system configured to radiate the one or more radar signals;

wherein the one or more radar signals when radiated by the antenna system comprise an aperture that has;

at least two neighboring elements that have a separation that is substantially unequal to the separation between at least two other neighboring elements within the aperture;

a mainlobe response with a width that is near or substantially equal to the minimum possible mainlobe width; and

a sidelobe response with substantially even energy distribution.

2. The radar transmission system of claim 1 further comprising a processing system configured to generate pulses using a Fourier transform which are used by the transmitter system to generate the one or more radar signals.

3. The radar transmission system of claim 1 wherein the mainlobe and sidelobe response results from that of a quadratic residue (QR) pattern.

4. The radar transmission system of claim 1 wherein the mainlobe and sidelobe response results from that of a pseudo-random pattern.

5. The radar transmission system of claim 1 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

6. The radar transmission system of claim 1 wherein the antenna system has elements that are unequally spaced.

7. The radar transmission system of claim 1 wherein:

the antenna system has elements that are equally spaced; and

the transmission system is configured to drive the antenna system elements to cause the aperture elements that are active to have substantially unequal separations.

61. The radar transmission system of claim 1 wherein the stated characteristics of the aperture exist in two dimensions.

62. The radar transmission system of claim 1 wherein the stated characteristics of the aperture exist in three dimensions.

8. Non-transitory, tangible, computer-readable storage media containing programming code which, when executed by a computer system, causes an associated transmitter system and antenna system to radiate radar signals that comprise an aperture that has:

at least two neighboring elements that have a separation that is substantially unequal to the separation between at least two other neighboring elements within the aperture;

a mainlobe response with a width that is near or substantially equal to the minimum possible mainlobe width; and

a sidelobe response with substantially even energy distribution.

9. The computer-readable storage media of claim 8 wherein the programming code, when executed by a computer system, causes the computer system to generate pulses using a Fourier transform which are converted into the radar signals by the transmitter system.

10. The computer-readable storage media of claim 8 wherein the mainlobe and sidelobe response results from that of a quadratic residue (QR) pattern.

11. The computer-readable storage media of claim 8 wherein the mainlobe and sidelobe response results from that of a pseudo-random pattern.

12. The computer-readable storage media of claim 8 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

63. The media of claim 9 wherein the stated characteristics of the aperture exist in two dimensions.

64. The media of claim 9 wherein the stated characteristics of the aperture exist in three dimensions.

13. A radar reception system comprising:

a receiver configured to receive one or more radiated radar signals that comprise an aperture which includes a first data set having a plurality of values based on a radar waveform return from a set of transmitted radar pulses; and

a processing system configured to create a second data set comprising the first data set minus at least one significant value from the first data set and its effects on other values within the first data set when the transmitted aperture has;

a separation between at least two neighboring elements that is substantially unequal to the separation between at least two other neighboring elements within the aperture;

a mainlobe response with a width that is near or substantially equal to the minimum possible width; and

a sidelobe response with a substantially even distribution of energy.

14. The radar reception system of claim 13 wherein the processing system is configured to:

create a third data set comprising the at least one significant value from the first data set; and

combine the second and third datasets.

15. The radar reception system of claim 13 wherein the first data set includes a plurality of transformed values.

16. The radar reception system of claim 15 wherein the plurality of transformed values are frequency values.

17. The radar reception system of claim 13 wherein the at least one significant value includes a peak value in a frequency domain.

18. The radar reception system of claim 13 wherein the second data set includes a number of peak values from the first data set chosen based on predetermined selection criteria.

19. The radar reception system of claim 13 wherein the processing system is configured to determine the effects of the at least one significant value by calculating a plurality of propagated effects from the at least one significant value.

20. The radar reception system of claim 13 wherein the processing system is configured to create the second data set by:

identifying at least one peak value in the first data set;

creating a peak correction function approximation using the at least one peak value; and

removing the peak correction function approximation from the first data.

21. The radar reception system of claim 13 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

65. The radar reception system of claim 15 wherein the stated characteristics of the aperture exist in two dimensions.

66. The radar reception system of claim 15 wherein the stated characteristics of the aperture exist in three dimensions.

22. Non-transitory, tangible, computer-readable storage media containing programming code which, when executed by a computer system, creates a second data set comprising a first data set having a plurality of values based on a radar waveform return from a set of transmitted radar pulses that comprise an aperture, minus at least one significant value from the first data set and its effects on other values within the first data set, when the aperture has:

at least two neighboring elements that have a separation that is substantially unequal to the separation between at least two other neighboring elements within the aperture;

a mainlobe response with a width that is near or substantially equal to the minimum possible width; and

a sidelobe response with a substantially even distribution of energy.

23. The computer-readable storage media of claim 22 wherein the programming code, when executed by the computer system:

creates a third data set comprising the at least one significant value from the first data set; and

combines the second and third datasets.

24. The computer-readable storage media of claim 22 wherein the first data set includes a plurality of transformed values.

25. The computer-readable storage media of claim 24 wherein the plurality of transformed values are frequency values.

26. The computer-readable storage media of claim 22 wherein the at least one significant value includes a peak value in a frequency domain.

27. The computer-readable storage media of claim 22 wherein the second data set includes a number of peak values from the first data set chosen based on predetermined selection criteria.

28. The computer-readable storage media of claim 22 wherein the programming code, when executed by the computer system, determines the effects of the at least one significant value by calculating a plurality of propagated effects from the at least one significant value.

29. The computer-readable storage media of claim 22 wherein the programming code, when executed by the computer system, creates the second data set by:

identifying at least one peak value in the first data set;

creating a peak correction function approximation using the at least one peak value; and

removing the peak correction function approximation from the first data.

30. The computer-readable storage media of claim 22 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

67. The media of claim 25 wherein the stated characteristics of the aperture exist in two dimensions.

68. The media of claim 25 wherein the stated characteristics of the aperture exist in three dimensions.

31. A radar transmission system comprising:

a transmitter system configured to generate one or more radar signals; and

an antenna system configured to radiate the one or more radar signals;

wherein the one or more radar signals when radiated by the antenna system comprise an aperture that has at least two neighboring elements that have a separation that is at least twice the shortest separation between at least two other neighboring elements within the aperture.

32. The radar transmission system of claim 31 further comprising a processing system configured to generate pulses using a Fourier transform which are used by the transmitter system to generate the one or more radar signals.

33. The radar transmission system of claim 31 wherein the mainlobe and sidelobe response results from that of a quadratic residue (QR) pattern.

34. The radar transmission system of claim 31 wherein the mainlobe and sidelobe response results from that of a pseudo-random pattern.

35. The radar transmission system of claim 31 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

36. The radar transmission system of claim 31 wherein the antenna system has elements that are unequally spaced.

37. The radar transmission system of claim 31 wherein:

the antenna system has elements that are equally spaced; and

the transmission system is configured to drive the antenna system elements to cause the active aperture elements to have the substantially unequal separations.

69. The radar transmission system of claim 35 wherein the stated characteristics of the aperture exist in two dimensions.

70. The radar transmission system of claim 35 wherein the stated characteristics of the aperture exist in three dimensions.

38. Non-transitory, tangible, computer-readable storage media containing programming code which, when executed by a computer system, causes an associated transmitter system and antenna system to radiate radar signals which comprise an aperture that has at least two neighboring elements that have a separation that is at least twice the shortest separation between at least two other neighboring elements within the aperture.

39. The computer-readable storage media of claim 38 wherein the programming code, when executed by a computer system, causes the computer system to generate pulses using a Fourier transform which are converted into the radar signals by a transmitter system.

40. The computer-readable storage media of claim 38 wherein the mainlobe and sidelobe response results from that of a quadratic residue (QR) pattern.

41. The computer-readable storage media of claim 38 wherein the mainlobe and sidelobe response results from that of a pseudo-random pattern.

42. The computer-readable storage media of claim 38 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

43. A radar reception system comprising:

a receiver configured to receive one or more radar signals that comprise an aperture which includes a first data set having a plurality of values based on a radar waveform return from a set of transmitted radar pulses; and

a processing system configured to create a second data set comprising the first data set minus at least one significant value from the first data set and its effects on other values within the first data set when the transmitted aperture has at least two neighboring elements that have a separation that is at least twice the shortest separation between at least two other neighboring elements within the aperture.

44. The radar reception system of claim 43 wherein the processing system is configured to:

create a third data set comprising the at least one significant value from the first data set; and

combine the second and third datasets.

45. The radar reception system of claim 43 wherein the first data set includes a plurality of transformed values.

46. The radar reception system of claim 45 wherein the plurality of transformed values are frequency values.

47. The radar reception system of claim 43 wherein the at least one significant value includes a peak value in a frequency domain.

48. The radar reception system of claim 43 wherein the second data set includes a number of peak values from the first data set chosen based on predetermined selection criteria.

49. The radar reception system of claim 43 wherein the processing system is configured to determine the effects of the at least one significant value by calculating a plurality of propagated effects from the at least one significant value.

50. The radar reception system of claim 43 wherein the processing system is configured to create the second data set by:

identifying at least one peak value in the first data set;

creating a peak correction function approximation using the at least one peak value; and

removing the peak correction function approximation from the first data.

51. The radar reception system of claim 43 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

71. The media of claim 43 wherein the stated characteristics of the aperture exist in two dimensions.

72. The media of claim 43 wherein the stated characteristics of the aperture exist in three dimensions.

73. The radar reception system of claim 49 wherein the stated characteristics of the aperture exist in two dimensions.

74. The radar reception system of claim 49 wherein the stated characteristics of the aperture exist in three dimensions.

52. Non-transitory, tangible, computer-readable storage media containing programming code which, when executed by a computer system, creates a second data set comprising a first data set having a plurality of values based on a radar waveform return from a set of transmitted radar pulses that comprise an aperture, minus at least one significant value from the first data set and its effects on other values within the first data set, when the aperture has at least two neighboring elements that have a separation that is at least twice the shortest separation between at least two other neighboring elements within the aperture.

53. The computer-readable storage media of claim 52 wherein the programming code, when executed by the computer system:

creates a third data set comprising the at least one significant value from the first data set; and

combines the second and third datasets.

54. The computer-readable storage media of claim 52 wherein the first data set includes a plurality of transformed values.

55. The computer-readable storage media of claim 54 wherein the plurality of transformed values are frequency values.

56. The computer-readable storage media of claim 52 wherein the at least one significant value includes a peak value in a frequency domain.

57. The computer-readable storage media of claim 52 wherein the second data set includes a number of peak values from the first data set chosen based on predetermined selection criteria.

58. The computer-readable storage media of claim 52 wherein the programming code, when executed by the computer system, determines the effects of the at least one significant value by calculating a plurality of propagated effects from the at least one significant value.

59. The computer-readable storage media of claim 52 wherein the programming code, when executed by the computer system, creates the second data set by:

identifying at least one peak value in the first data set;

creating a peak correction function approximation using the at least one peak value; and

removing the peak correction function approximation from the first data.

60. The computer-readable storage media of claim 52 wherein the substantially unequal separation includes substantially unequal separation in each of multiple dimensions.

75. The media of claim 59 wherein the stated characteristics of the aperture exist in two dimensions.

76. The media of claim 59 wherein the stated characteristics of the aperture exist in three dimensions.