METHOD AND APPARATUS FOR REMOTELY DERIVING THE VELOCITY VECTOR OF AN IN-FLIGHT BALLISTIC PROJECTILE

• US 20050012657A1
• Filed: 06/16/2003
• Published: 01/20/2005
• Est. Priority Date: 06/16/2003
• Status: Active Grant

• Current Assignee: General Dynamics Mission Systems Inc. (General Dynamics Corporation)
• Original Assignee: General Dynamics Advanced Information Systems Incorporated (General Dynamics Corporation)
• Inventors: Mohan, Paul
• Granted Patent: US 6,956,523 B2
• Time in Patent Office: Days
• US Class Current: 342/133
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/589 measuring the velocity vector
• CPC Class Codes: G01S 7/025 involving the transmission of linearly polarised waves

Abstract

A system and method for rapidly determining the source of an incoming projectile applies controlled, active RF energy source(s) to illuminate a target area/projectile, and exploits Doppler induced frequency shifts from multiple receivers to develop a vector solution. The preferred solution applies continuous wave (CW) RF illuminators to flood a local region with a controlled source of radio frequency energy and one or more displaced receiver elements. The system operates multi-statically and as an incoming projectile enters the illuminated region, reflected energy from one or more illuminators is detected by one or more displaced RF receivers. Doppler shifts imparted on the reflected signals are detected by the receivers as the projectile moves through the region. Appropriate processing of the receiver outputs generates Doppler time-frequency profiles that are used to derive an estimate of the projectile flight vector in 3-space (x,y,z). The vector parameters can, among other things, feed a laser designator that projects a beam along the derived flight path to support identification of the source, or be relayed to remote personnel by a data link where the projectile vector can be displayed on a map.

Claims

1. a system for deriving the flight path of a projectile, comprising:

a source of radio-frequency (RF) energy directed into a region including the flight path;

one or more RF receivers for receiving energy reflected by the projectile as it travels along the flight path; and

a processor interconnected to the RF receivers for generating a Doppler time-frequency profile of the flight path and a three-dimensional projectile flight vector.

2. The system of claim 1, wherein the RF sources operate in a continuous-wave (CW) mode.

3. The system of claim 1, further including an indicator used to identify the source of the projectile as a function of the projectile flight vector.

4. The system of claim 1, further including a laser beam indicator used to illuminate the source of the projectile as a function of the projectile flight vector.

5. The system of claim 1, further including an interface to a map enabling the geographic source of the projectile to be displayed as a function of the projectile flight vector.

6. The system of claim 1, including two or more RF sources operating at different frequencies.

7. The system of claim 1, wherein the RF source and a receiver are physically offset.

8. The system of claim 1, including two or more co-located source-receiver pairs, each pair being physically offset.

9. The system of claim 1, wherein the processor uses a time history of the Doppler time-frequency profile.

10. The system of claim 1, wherein the processor takes the effect of air friction on the projectile into account when generating the time-frequency profile.

11. The system of claim 1, wherein the processor relies on narrowband Doppler signatures.

12. The system of claim 1, wherein the processor uses a Doppler passband that is intentionally spaced apart from the carrier frequency of the source.

13. The system of claim 1, wherein the source and receivers operate in the ultra-high frequency band.

14. The system of claim 1, wherein the source and receivers use linear polarization.

15. A method of determining deriving the flight path of a projectile, comprising the steps of:

transmitting radio-frequency (RF) energy into a region including the flight path;

receiving energy reflected by the projectile as it travels along the flight path; and

generating a Doppler time-frequency profile of the flight path and a three-dimensional projectile flight vector.

16. The method of claim 15, wherein the RF sources operate in a continuous-wave (CW) mode.

17. The method of claim 15, further including the step of identifying the source of the projectile as a function of the projectile flight vector.

18. The method of claim 15, further including the step of using a laser beam to illuminate the source of the projectile as a function of the projectile flight vector.

19. The method of claim 15, further including the step displaying the flight path on a map.

20. The method of claim 15, including the step of operating two or more RF sources at different frequencies.

21. The method of claim 15, including the step of physically separating the RF source and a receiver.

22. The method of claim 15, including the step of co-locating two or more source-receiver pairs, each pair being physically offset.

23. The method of claim 15, further including the step of using a time history of the Doppler time-frequency profile.

24. The method of claim 15, further including the step of taking the effect of air friction on the projectile into account when computing the flight path.

25. The method of claim 15, further including the step of using narrowband Doppler signatures.

26. The method of claim 15, further including the step of using a Doppler passband that is intentionally spaced apart from the carrier frequency of the source.

27. The method of claim 15, further including the step of operating the source and receivers in the ultra-high frequency band.

28. The method of claim 15, wherein the source and receivers use linear polarization.

29. A system for deriving the flight path of a projectile, comprising:

a plurality of continuous-wave (CW) radio-frequency (RF) transmitters, each directing energy at a different carrier frequency into a region of overlap including the flight path;

one or more RF receivers for receiving energy reflected by the projectile as it travels along the flight path; and

a processor interconnected to the RF receivers for generating a Doppler time-frequency profile and time history of the flight path to determine a multi-dimensional projectile flight vector.

30. The system of claim 29, further including an indicator used to identify the source of the projectile as a function of the projectile flight vector.

31. The system of claim 29, further including a laser beam indicator used to illuminate the source of the projectile as a function of the projectile flight vector.

32. The system of claim 29, further including an interface to a map enabling the geographic source of the projectile to be displayed as a function of the projectile flight vector.

33. The system of claim 29, wherein the RF source and a receiver are physically offset.

34. The system of claim 29, including two or more co-located source-receiver pairs, each pair being physically offset.

35. The system of claim 29, wherein the processor takes the effect of air friction on the projectile into account when generating the time-frequency profile.

36. The system of claim 29, wherein the processor relies on narrowband Doppler signatures.

37. The system of claim 29, wherein the processor uses a Doppler passband that is intentionally spaced apart from the carrier frequency of the source.

38. The system of claim 29, wherein the source and receivers operate in the ultra-high frequency band.

39. The system of claim 29, wherein the source and receivers use linear polarization.