System and method for target signature calculation and recognition

• US 8,130,136 B2
• Filed: 03/14/2003
• Issued: 03/06/2012
• Est. Priority Date: 03/15/2002
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Lodwig, Richard A., Adams, Bonnie L.
• Primary Examiner(s): Brainard, Timothy A
• Application Number:
  US10/388,237
• Publication Number:
  US 20110210885A1
• Time in Patent Office: 3,280 Days
• Field of Search: 342/59, 342/126, 342/148, 342/149, 342/155, 342/175
• US Class Current: 342/59
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 7/411 Identification of targets based on measurements of radar reflectivity G01S7/415 takes precedence

Abstract

The present invention is directed to a system and method for the identification of a target object in PCL radar applications. The disclosed embodiments describe the systems and methods used in the identification of a target object from the collection of data representing specific target object features, such as velocity, altitude, fuselage length, wing length, or wing sweepback angle, and the comparison of selected target object features with a database of known aircraft features. The present invention also provides for the calculation of feature dimensions, such as the fuselage length, wing length, or wing sweepback angle from measurements associated with a peak signal lobe as a function of a bistatic aspect angle.

Claims

1. A system for detecting and identifying a target object using signals transmitted by one or more independent transmitters, comprising:

an antenna for receiving direct signals from the transmitters and reflected signals reflected by the target object;

a signal processing subsystem connected to the antenna for processing the signals received by the antenna;

a signature processing subsystem for calculating target object signature information, wherein the signature processing subsystem calculates target object signature information by calculating peak lobe data from a peak lobe reflected by a target object feature and calculating the dimension of the target object feature from the peak lobe data; and

a display subsystem for selectively displaying the target object signature information.

2. The system of claim 1, wherein the direct and reflected signals received by the antenna are in the 30 MHz to 300 MHz frequency range.

3. The system of claim 1, wherein the signature processing subsystem calculates the target object signature information using a reflected signal amplitude as a function of a bistatic aspect angle.

4. The system of claim 1, wherein the signature processing subsystem calculates an included angle.

5. The system of claim 1, wherein the signature processing subsystem calculates an aspect angle.

6. The system of claim 1, wherein the signature processing subsystem calculates the target object signature information using a monostatic equivalent wavelength.

7. The system of claim 1, wherein the signature processing subsystem approximates a reflected beam width by taking into account a mirror effect.

8. The system of claim 1, wherein the signature processing subsystem approximates a reflected beam width by taking into account an amplitude doubling effect.

9. The system of claim 1, further comprising a database of signature data for comparison with the target object signature information.

10. A system for detecting and identifying a target object, comprising:

one or more transmitters for transmitting signals;

an antenna for receiving direct signals from the transmitters and reflected signals reflected by the target object;

a signal processing subsystem connected to the antenna for processing the signals received by the antenna;

a signature processing subsystem for calculating target object signature information using a reflected signal amplitude as a function of a bistatic aspect angle, wherein the signature processing subsystem calculates a length of a target object feature by calculating a value by multiplying a wavelength of a reflected signal by a constant and dividing the value by the sine of twice a heading change angle; and

a display subsystem for selectively displaying the target object signature information.

11. The system of claim 10, wherein the one or more transmitters transmit in the 30 MHz to 300 MHz frequency range.

12. The system of claim 10, wherein the signature processing subsystem calculates an included angle.

13. The system of claim 10, wherein the signature processing subsystem calculates an aspect angle.

14. The system of claim 10, wherein the signature processing subsystem calculates the target object signature information using a monostatic equivalent wavelength.

15. The system of claim 10, wherein the signature processing subsystem approximates a reflected beam width by taking into account a mirror effect.

16. The system of claim 10, wherein the signature processing subsystem approximates a reflected beam width by taking into account an amplitude doubling effect.

17. The system of claim 10, further comprising a database of signature data for comparison with the target object signature information.

18. A method for detecting and identifying a target object using signals transmitted by one or more transmitters, comprising the steps of:

detecting a transmitted signal from the one or more independent transmitters;

detecting the transmitted signal reflected by a target object;

calculating the wavelength of the reflected signal;

calculating an included angle;

calculating a bisector aspect angle; and

calculating the length of a target object feature based on the wavelength as a function of the bisector aspect angle.

19. The method of claim 18, wherein the step of calculating the length of the target object feature comprises the sub-steps of:

calculating a value by multiplying the wavelength by a constant; and

dividing the value by the sine of twice a heading change angle.

20. The method of claim 18, wherein the step of detecting a transmitted signal reflected by a target object further comprises the sub-step of detecting an average reflected signal.

21. The method of claim 18, wherein the step of detecting a transmitted signal reflected by a target object further comprises the sub-step of detecting a peak reflected signal.

22. A method for detecting and identifying a target object using signals transmitted by one or more transmitters, comprising the steps of:

detecting a transmitted signal from the one or more independent transmitters;

detecting the transmitted signal reflected by a target object;

calculating a wavelength of the reflected signal;

calculating a heading change angle; and

calculating the length of a target object feature based on the wavelength and the heading change angle.

23. A system for identifying a target object using signals from one or more transmitters, comprising:

a signal processing unit for calculating data representing specific features of a target object, including calculating a feature dimension of the target object using a received peak lobe as a function of a bistatic aspect angle and a heading change between −

3 dB points of the received peak lobe; and

a display element for displaying identification data associated with the target object.

24. The system of claim 23, further comprising a library of known aircraft data for comparing with the data calculated by the signal processing unit.

25. The system of claim 23, wherein the signal processing unit further comprises:

an antenna element for receiving the direct signals transmitted by the one or more transmitters and the reflected signals transmitted by the one or more transmitters, reflected by the target object, and received by the antenna element; and

a signal processing segment for processing the direct signals and the reflected signals.

26. The system of claim 25, wherein the antenna element further comprises:

a reference antenna for receiving the direct signals; and

a target antenna for receiving the reflected signals.

27. The system of claim 25, wherein the signal processing segment further comprises:

a receiver subsystem for receiving the signal received by the antenna element;

a signal processing subsystem; and

a data storage element for storing a library of known aircraft data for comparing with the data calculated by the signal processing unit.

28. The system of claim 27, wherein the receiver subsystem further comprises a reference receiver for receiving the direct signals from the antenna element.

29. The system of claim 27, wherein the receiver subsystem further comprises a target receiver for receiving the reflected signals from the antenna element.

30. The system of claim 27, wherein the signal processing subsystem further comprises:

one or more signal processors; and

a signature processing element associated with the one or more signal processors for calculating target object feature dimensions using the received peak lobe as a function of a bistatic aspect angle and the heading change between −

3 dB points of the received peak lobe.

31. The system of claim 30, wherein the signature processing element further filters the received peak lobe with a polynomial representation of the expected signal amplitude as a function the bistatic aspect angle.

32. The system of claim 27, wherein the signal processing subsystem further comprises a detection and tracking processing element for detecting and calculating the location and movement of the target object.

33. The system of claim 27, wherein the one or more signal processors further comprise narrowband signal processors.

34. The system of claim 27, wherein the one or more signal processors further comprise one or more wideband signal processors.

35. A method for identifying a target object, comprising the steps of:

detecting and tracking the target object;

calculating signature data for the target object; and

identifying the target;

wherein the step of calculating signature data further comprises the steps of;

calculating peak lobe data from a peak lobe reflected by a target object feature; and

calculating the dimension of the target object feature from the peak lobe data.

36. The method of claim 35, wherein the step of detecting and tracking the target object further comprises the steps of:

detecting the target object by receiving direct signals and reflected signals reflected by the target object;

calculating the position of the target object with the direct and reflected signals;

calculating the heading of the target object by updating the position of the target object over a period of time; and

calculating the velocity of the target object by comparing the distance traveled by the target object with respect to time.

37. The method of claim 35, further comprising the step of filtering the peak lobe with a polynomial fit representation of the expected peak lobe.

38. The method of claim 35, wherein the step of calculating peak lobe data further comprises the steps of:

calculating the incident direction of a signal path from a transmitter to the target object;

calculating the reflected direction of a reflected signal path from the target object to a receiver;

calculating the bisector vector of the included angle between the incident direction and the reflected direction;

calculating a bistatic aspect angle between the target object'"'"'s heading and the bisector vector;

calculating a peak lobe as a function of the bistatic aspect angle;

calculating an effective wave length of the peak lobe signal;

calculating a heading change between −

3 db power points of the peak lobe.

39. The method of claim 38, further comprising the step of calculating a wing sweepback angle.

40. The method of claim 39, wherein the step of calculating a wing sweepback angle further comprises the step of adding ninety degrees to the bistatic aspect angle of the peak lobe reflected by a wing of the target object.

41. The method of claim 38, wherein the step of calculating the dimension of the target object feature from the peak lobe data further comprises the steps of:

multiplying the effective wavelength with a constant value; and

dividing by the sine of twice the heading change.

42. The method of claim 41, wherein the step of multiplying the effective wavelength with a constant value further comprises multiplying the wavelength by 0.638.

43. The method of claim 35, wherein the step of identifying the target object further comprises the steps of:

comparing calculated features of the target object with a database of known features; and

identifying the target object with a match in the database of known features.