System and method for onboard detection of ballistic threats to aircraft

• US 6,980,151 B1
• Filed: 06/14/2004
• Issued: 12/27/2005
• Est. Priority Date: 06/14/2004
• Status: Expired due to Fees

• Current Assignee: MDA Information Systems LLC (Galileo Parent, Inc.)
• Original Assignee: General Dynamics Advanced Information Systems Incorporated (General Dynamics Corporation)
• Inventors: Mohan, Paul L.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/868,675
• Publication Number:
  US 20050275582A1
• Time in Patent Office: 561 Days
• Field of Search: 342 1- 20, 342/59, 342 82-103, 342/175, 342192-197, 342 73- 81, 342/104, 342/109, 342/113, 342/118, 342/126, 342128-133, 342/27, 342/28, 342 61- 67, 342450-465
• US Class Current: 342/13
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 7/414 Discriminating targets with respect to background clutter
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

A bi-static continuous wave radar system and related methods for detecting incoming threats from ballistic projectiles includes a remote source of RF illumination, and a local receiver installed in one or more target aircraft. A first receiving channel acquires direct path illumination from the source and provides a reference signal, and a second receiving channel acquires a scatter signal reflected by a projectile. A processor coupled to each receiver corrects scatter signal Doppler offset induced by relative source motion, isolates narrowband Doppler signals to derive signatures characteristic of the projectile, and by executing appropriate algorithms, compares the derived signatures to modeled signatures stored in memory. If the comparison yields a substantial similarity, the processor outputs a warning signal sufficient to initiate defensive countermeasures.

Claims

1. A radar system for detecting a presence of a ballistic projectile, comprising:

a source of radio frequency energy, sited remotely from a target, for illuminating airspace around the target;

a receiver, sited locally to the target, the receiver having first and second receiving channels, the first receiving channel configured to acquire a reference signal from the source, and the second receiving channel configured to acquire a second signal from the source, the second signal reflected by the projectile; and

a signal processor including a means for determining whether the projectile poses an imminent threat to the target.

2. The system of claim 1 further comprising a means for generating a warning signal responsive to the signal processor detecting the presence of the ballistic projectile.

3. The system of claim 1 further comprising a means for deploying one or more countermeasures responsive to the signal processor detecting an imminent threat.

4. The system of claim 3 wherein the deploying means comprises releasing chaff or thermal decoys.

5. The system of claim 3 wherein the signal processor derives one or more Doppler signals from the reflected signal and the reference signal.

6. The system of claim 5 wherein the one or more Doppler signals comprise a Doppler bandwidth.

7. The system of claim 5 wherein the one or more Doppler signals comprise a time-frequency profile.

8. The system of claim 5 wherein the signal processor outputs one or more characteristic signatures of the projectile derived from the one or more Doppler signals.

9. The system of claim 8 wherein the deploying means deploys the one or more countermeasures responsive to the processor outputting the one or more characteristic signatures.

10. The system of claim 8 wherein at least one of the characteristic signatures comprises a radar cross section.

11. The system of claim 10 wherein the radar cross section lies within a warhead range.

12. The system of claim 8 wherein at least one of the characteristic signatures comprises a flight profile of the projectile.

13. The system of claim 12 wherein the one or more countermeasures are employed responsive to the processor predicting a collision between the projectile and the target based on the flight profile.

14. The system of claim 12 wherein the flight profile accounts for in-flight maneuvering by the projectile.

15. The system of claim 8 further comprising a memory coupled to the processor, the memory storing data representing one or more modeled signatures of ballistic projectiles.

16. The system of claim 15 wherein the deploying means deploys the one or more countermeasures responsive to the processor determining that at least one of the one or more characteristic signatures is substantially similar to any of the one or more modeled signatures.

17. The system of claim 1 wherein the source comprises a continuous wave transmitter.

18. The system of claim 17 wherein the continuous wave is modulated.

19. The system of claim 1 wherein the reference signal is acquired by direct path illumination from the source.

20. The system of claim 1, wherein the means for determining is a detection module, the detection module being configured to compare data associated with the second signal with a match criteria to determine if the ballistic projectile poses an imminent threat.

21. A radar system for detecting an imminent threat from a ballistic projectile, comprising:

a source of radio frequency energy, sited remotely from a target, for illuminating airspace around the target;

a receiver, sited locally to the target, the receiver having first and second receiving channels, the first receiving channel configured to acquire a reference signal from the source, and the second receiving channel configured to acquire a second signal from the source, the second signal reflected by the projectile;

a signal processor, sited locally to the target, for processing the reflected signal and the reference signal to derive one or more characteristic signatures induced by the projectile, the signal processor further comprising;

an analyzer for removing, from the reflected signal, Doppler effects caused by motion of the source;

a discriminator for subtracting background noise from the reflected signal;

one or more memory modules coupled to the processor for storing one or more modeled signatures; and

detection logic for comparing the one or more derived characteristic signatures to the one or more modeled signatures;

whereby if the comparison detects a substantial similarity between at least one of the characteristic signatures and at least one of the modeled signatures, the signal processor outputs a warning signal.

22. The system of claim 21 further comprising a means for deploying one or more countermeasures responsive to the warning signal.

23. The system of claim 22 wherein the deploying means comprises releasing chaff or thermal decoys.

24. The system of claim 22 wherein the source comprises a transmitter.

25. The system of claim 24 wherein the transmitter transmits a continuous wave.

26. The system of claim 25 wherein the continuous wave is modulated.

27. The system of claim 21 wherein the reference signal is acquired by direct path illumination from the source.

28. The system of claim 21 wherein at least one of the derived characteristic signatures comprises one or more sets of spectral amplitude and frequency thresholds.

29. The system of claim 21 wherein at least one of the known signatures comprises one or more sets of spectral amplitude and frequency thresholds.

30. The system of claim 21 wherein at least one of the derived characteristic signatures comprises a narrow band Doppler signal.

31. The system of claim 21 wherein at least one of the derived characteristic signatures comprises a radar cross section.

32. The system of claim 31 wherein the radar cross section lies within a warhead range.

33. The system of claim 21 wherein at least one of the derived characteristic signatures comprises a flight profile of the projectile.

34. The system of claim 33 wherein the detection logic outputs a warning signal responsive to the processor predicting a collision between the projectile and the target based on the flight profile.

35. The system of claim 33 wherein the flight profile accounts for in-flight maneuvering by the projectile.

36. A method for detecting an imminent threat from a ballistic projectile, comprising:

illuminating airspace around a target with a source of radio frequency energy, the source sited remotely from the target;

receiving a reference signal from the source in a first channel of a receiver sited locally at the target;

receiving, in a second channel of the receiver, a second signal from the source, the second signal reflected by the projectile; and

processing the reflected signal and the reference signal to determine whether the projectile poses an imminent threat to the target.

37. The method of claim 36 further comprising deploying one or more countermeasures responsive to determining an imminent threat.

38. The method of claim 37 wherein the deploying step comprises releasing chaff.

39. The method of claim 37 wherein the deploying step comprises releasing thermal decoys.

40. The method of claim 37 wherein the processing step further comprises deriving one or more Doppler signals from the reflected signal and the reference signal.

41. The method of claim 40 wherein the one or more Doppler signals comprise a Doppler bandwidth.

42. The method of claim 40 wherein the one or more Doppler signals comprise a time-frequency profile.

43. The method of claim 40 wherein the processing step further comprises deriving one or more characteristic signatures of the projectile from the one or more Doppler signals.

44. The method of claim 43 wherein the deploying step further comprises deploying the one or more countermeasures responsive to deriving the one or more characteristic signatures.

45. The method of claim 44 wherein at least one of the characteristic signatures comprises a radar cross section.

46. The method of claim 45 wherein the radar cross section lies within a warhead range.

47. The method of claim 44 wherein at least one of the characteristic signatures comprises a flight profile of the projectile.

48. The method of claim 47 wherein the processing step further comprises predicting whether the projectile and the target will collide based on the flight profile, and wherein the deploying step further comprises deploying one or more countermeasures responsive to a predicted collision.

49. The method of claim 47 wherein the processing step further comprises deriving the flight profile by accounting for in-flight maneuvering by the projectile.

50. The method of claim 43 wherein the deploying step further comprises deploying the one or more countermeasures responsive to deriving at least one of the one or more characteristic signatures that substantially matches any of one or more modeled signatures stored in a memory.

51. The method of claim 36 wherein the illuminating step further comprises transmitting continuous wave radar.

52. The method of claim 51 wherein the continuous wave radar is modulated.

53. The method of claim 36 wherein the first receiving step further comprises acquiring the reference signal by direct path illumination from the source.

54. A method for detecting imminent threats from ballistic projectiles to one or more aircraft targets, comprising:

illuminating airspace around the one or more targets with an RF transmitter sited remotely from the one or more targets;

receiving, in a first channel of a receiver sited locally at each of the one or more targets, a reference signal from the transmitter;

receiving, in a second channel of each receiver, a second signal from the transmitter, the second signal reflected by a projectile;

subtracting background noise from the reflected signal received at each of the one or more targets;

deriving, at each of the one or more targets, one or more characteristic signatures of the projectile, from the reflected signal and the reference signal received at each of the one or more targets;

comparing the one or more derived signatures to one or more modeled signatures stored in a memory; and

producing a warning signal if at least one of the derived signatures is substantially similar to at least one of the modeled signatures.

55. The method of claim 54 further comprising deploying one or more countermeasures responsive to producing the warning signal.

56. The method of claim 55 wherein the deploying step further comprises releasing chaff or thermal decoys.

57. The method of claim 54 wherein the illuminating step further comprises transmitting continuous wave radar.

58. The method of claim 57 wherein the continuous wave radar is modulated.

59. The method of claim 54 wherein the first receiving step further comprises acquiring the reference signal by direct path illumination from the transmitter.

60. The method of claim 54 wherein at least one of the derived signatures comprises one or more sets of spectral amplitude and frequency thresholds.

61. The method of claim 54 wherein at least one of the modeled signatures comprises one or more sets of spectral amplitude and frequency thresholds.

62. The method of claim 54 wherein at least one of the derived signatures comprises a narrow band Doppler signal.

63. The method of claim 54 wherein at least one of the derived signatures comprises a radar cross section.

64. The method of claim 63 wherein the radar cross section lies within a warhead range.

65. The method of claim 54 wherein at least one of the derived signatures comprises a flight profile of the projectile.

66. The method of claim 65 wherein the comparing step further comprises predicting whether the projectile and the target will collide based on the flight profile, and wherein the producing step further comprises producing a warning signal responsive to predicting an imminent collision.

67. The method of claim 65 wherein the deriving step further comprises accounting for in-flight maneuvering by the projectile in deriving the one or more characteristic signatures.