Passive coherent location system and method

• US 6,522,295 B2
• Filed: 04/24/2001
• Issued: 02/18/2003
• Est. Priority Date: 04/24/2000
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Integrated Systems Incorporated (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Integrated Systems Incorporated (Martin Marietta Corporation)
• Inventors: Benner, Robert, Lodwig, Richard, Baugh, Kevin W.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US09/840,309
• Publication Number:
  US 20020005803A1
• Time in Patent Office: 665 Days
• Field of Search: 342/453
• US Class Current: 342/453
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 13/91 for traffic control G01S13/93 takes precedence
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

A system and method for enhancing object state awareness is disclosed. The system includes a receiver subsystem that receives reference signals from an uncontrolled transmitter and scattered transmissions originating from the uncontrolled transmitter and scattered by an object. The system also includes a front-end processing subsystem that determines a radial velocity of the object based on the received transmissions. The system also includes a back-end processing subsystem that determines object state estimates based on the determined radial velocity.

Claims

1. A system for enhancing object state awareness comprising:

a receiver subsystem to receive a reference signal from an uncontrolled transmitter and scattered transmissions originating from the uncontrolled transmitter and scattered by an object;

a front-end processing subsystem to determine a radial velocity of the object based on the received transmissions and to buffer digitized transmission replicas of the received transmissions; and

a back-end processing subsystem to receive the digitized transmission replicas and to determine object state estimates based on the determined radial velocity.

2. The system of claim 1, wherein said scattered transmissions comprise ambient transmissions.

3. The system of claim 1, further comprising initial position information for said object, wherein said initial position information is communicated with said reference signal.

4. The system of claim 1, further comprising an output device to display said object state estimates.

5. The system of claim 1, further comprising a communication link to couple said receiver subsystem, said front-end processing subsystem and said back-end processing subsystem.

20. The system of claim 1, wherein said reference signal is independent of a location for said uncontrolled transmitter.

6. A passive coherent location system for monitoring a predetermined location, comprising:

a receiver subsystem to receive scattered transmissions scattered by an object and to output digitized signals of said scattered transmissions, said scattered transmissions originating from an uncontrolled transmitter;

a front-end processing subsystem to determine a frequency-difference-of-arrival for said digitized signals and to buffer digitized transmission replicas of said digitized signals; and

a back-end processing subsystem to receive the digitized transmission replicas and to determine positional information for said object in accordance with said frequency-difference-of-arrival.

7. The system of claim 6, further comprising an output device to provide said positional information for said object.

8. The system of claim 6, further comprising a reference signal from said uncontrolled transmitter, said reference signal being used to determine said frequency-difference-of-arrival for said digitized signals.

9. The system of claim 6, wherein a velocity of said object is determined from said frequency-difference-of-arrival.

10. The system of claim 6, further comprising an antenna subsystem to detect said scattered transmissions.

11. The system of claim 10, wherein said antenna subsystem comprises a phased array antenna.

12. The system of claim 6, wherein said receiver subsystem comprises an ultrahigh dynamic range receiver.

13. The system of claim 6, further comprising a communication link between said front-end processing subsystem and said back-end processing subsystem.

21. The system of claim 6, wherein said scattered transmissions is independent of a location for said uncontrolled transmitter.

14. A method for determining an updated state estimate for an object, comprising:

receiving a reference transmission from an uncontrolled transmitter, and a scattered transmission that originated from said uncontrolled transmitter and scattered by said object;

comparing said received transmissions to determine a frequency-difference-of-arrival;

updating a previous state estimate based on said determined frequency-difference-of-arrival; and

buffering digitized transmission replicas of said received transmissions, wherein said digitized replicas are received by a back-end processing subsystem.

15. The method of claim 14, further comprising determining an initial state object estimate.

16. The method of claim 14, further comprising selecting said uncontrolled transmitter from a plurality of transmitters.

17. The method of claim 14, further comprising determining whether said object is moving.

18. The method of claim 14, further comprising outputting said updated state estimate.

19. The method of claim 14, further comprising terminating said receiving when said object is out-of-range.

22. The method of claim 14, wherein said reference transmission is independent of a location for said uncontrolled transmitter.