Real-time multistatic radar signal processing system and method

• US 20060238407A1
• Filed: 04/22/2005
• Published: 10/26/2006
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: Raytheon BBN Technlogies Corp. (Rtx Corporation)
• Original Assignee: BBNT Solutions LLC (Rtx Corporation)
• Inventors: Stickels, Ernest Scott, Butler, Gary Dana, Norris, David Earl, Wright, William Ray, Bourdelais, John Michael, Tiberio, Michael Anthony
• Granted Patent: US 7,199,750 B2
• Time in Patent Office: Days
• US Class Current: 342/90
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 7/006 using shared front-end circuitry, e.g. antennas G01S13/765, G01S13/825 take precedence
• CPC Class Codes: G01S 7/411 Identification of targets based on measurements of radar reflectivity G01S7/415 takes precedence

Abstract

A real-time signal processing engine robustly detects, localizes, tracks and classifies ground targets based on radar signals from a multistatic radar system. The system differentiates between different targets based on an optimized cost function, which can include the total returned normalized pulse energy. The local transmitters/receivers can communicate with each other via the transmitted radar signals.

Claims

1. A method for identifying a target by using a multistatic radar system having at least one radar transmitter and a plurality of radar receivers arranged in node pairs, the method comprising:

receiving at a receiver a radar signal from a corresponding transmitter of the node pair;

filtering the received radar signal and identifying from the filtered radar signal probable target data;

transmitting the probable target data from at least two transmitter-receiver node pairs to a central node;

identifying at the central node from the probable target data a location of a first target;

removing from the probable target data the data associated with the first target location; and

determining a location of an additional target from the remaining probable target data.

2. The method of claim 1, wherein filtering comprises suppressing out-of-band energy of the received signal.

3. The method of claim 1, wherein filtering comprises time-aligning successively received signals.

4. The method of claim 1, wherein filtering comprises scaling, smoothing and normalizing the received signals.

5. The method of claim 1, wherein identifying probable target data comprises determining backscattered energy of the received signal and comparing the backscattered energy with a predetermined reference value.

6. The method of claim 1, wherein identifying probable target data comprises determining a target speed and comparing the determined target speed with a probable target speed of the target.

7. The method of claim 1, wherein identifying the location of the first target comprises determining from the probable target data a total backscattered energy, and selecting as the location of the first target the location having a greatest total backscattered energy.

8. The method of claim 1, wherein identifying the location of the first target comprises associating a cost function with potential target locations, said cost function representing a measure of likelihood that a target is present at the location, and selecting the location of the first target by optimizing the cost function.

9. The method of claim 1, comprising classifying a target by

tracking an identified target over a predetermined time;

building a three-dimensional image of the target by analyzing target data received from a plurality of the node pairs;

monitoring changes in the three-dimensional image during the predetermined time; and

assigning a target type to the target based on the monitored changes.

10. The method of claim 9, wherein the assigned target type is selected from the group consisting of vehicles, livestock, and humans.

11. The method of claim 9, wherein the target type is assigned based on at least one of size and radar cross section of the target.

12. The method of claim 9, wherein the target type is assigned based on a change in radar cross section when the three-dimensional image is viewed from different directions.

13. The method of claim 1, comprising estimating a range for a likely bistatic angle for the probable target data from forward-scattering and backscattering radar cross sections.

14. The method of claim 1, comprising recording a target map with the first target and at least one additional target.

15. A method for identifying a target by using a multistatic radar system having at least one radar transmitter and a plurality of radar receivers forming node pairs, the method comprising:

receiving target data from a target in at least two receivers defining node pairs, the received target data defining a target ellipse at each of the node pairs;

determining points of intersection between the target ellipses;

associating a cost function with the points of intersection; and

assigning a first target to the point of intersection having the lowest cost function.

16. The method of claim 15, wherein the cost function comprises at least one of a received normalized pulse energy, a bistatic angle for the received pulse energy, a range —

velocity characteristic of the target, and a separation between closely-spaced points of intersection located on at least three intersecting ellipses.

17. The method of claim 15, further comprising

removing the target ellipses that include the target data for the first target;

and

assigning a second target to the point of intersection having the lowest cost function.

18. The method of claim 15, wherein the node pairs receive the target data from different vantage points, said target data indicative of a size and a radar cross section of a target.

19. A method for classifying a target by using a multistatic radar system having at least one radar transmitter and a plurality of radar receivers arranged in node pairs, the method comprising:

receiving at at least two receivers radar signals from the transmitter of a corresponding node pair;

associating the received radar signals with a target and with a relative motion of parts of targets;

determining a location of the target; and

classifying the target based on the radar signals received from a target and the relative motion of the parts of targets.

20. The method of claim 19, wherein the node pairs receive the radar signals from different vantage points to form a three-dimensional radar image of the target.

21. A multistatic radar tracking system comprising:

at least one radar transmitter and a plurality of radar receivers arranged in node pairs, said at least one transmitter emitting radar signals composed of ultra-short wide bandwidth radio frequency pulses;

a filter for identifying at the receiver level from a radar signal received at the receiver of a node pair a target ellipse for a potential target; and

a real-time radar signal processing engine that determines from at least two target ellipses a first target location, and determines an additional target location after removing the target ellipses used to determine the first target location.