Real-time multistatic radar signal processing system and method

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.