Multidirectional target detecting system and method

• US 8,624,773 B2
• Filed: 11/09/2010
• Issued: 01/07/2014
• Est. Priority Date: 11/09/2010
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Nguyen, Lam Huy, Sichina, Jeffrey
• Primary Examiner(s): Keith, Jack W
• Assistant Examiner(s): BYTHROW, PETER M
• Application Number:
  US12/942,362
• Publication Number:
  US 20120112957A1
• Time in Patent Office: 1,155 Days
• Field of Search: 342/25.R, 342/25.A, 342/25.B, 342/25.C, 342/25.D, 342/25.E, 342/25.F, 342 70- 72, 342/179
• US Class Current: 342/25.A
• CPC Class Codes: G01S 13/904 SAR modes
• CPC Class Codes: G01S 13/9041 Squint mode
• CPC Class Codes: G01S 13/9043 Forward-looking SAR

Abstract

A method and system for investigating and displaying an image of an area of interest comprising a moving vehicle; at least one processor for producing an image of the area of interest; at least one first transmitter for emitting first signals substantially in a first direction, the at least one first transmitter being operatively associated with the moving vehicle and the processor; at least one first receiver for receiving backscattered signals resulting from the first radar signals, the at least one first receiver being operatively associated with the moving vehicle and the processor; at least one second transmitter operatively for emitting second signals in a direction substantially opposite to the first direction, the at least one second transmitter being operatively associated with the moving vehicle and the processor; at least one second receiver for receiving backscattered signals resulting from the second signals, the at least one second receiver being operatively associated with the moving vehicle and the processor, a GPS subsystem for providing position data relating to the position of the vehicle; the at least one first receiver and the at least one second receiver operating to provide image data to the at least one processor; the at least one processor operating to combine image data from the at least one first receiver and the at least one second receiver with the position data to form a single image; and a display to display the combined image data.

Claims

1. A system for investigating and displaying an image of an area of interest comprising:

a moving vehicle;

at least one processor for producing an image of the area of interest;

at least one first transmitter for emitting first radar signals substantially in a first direction towards the area of interest, the at least one first transmitter being operatively associated with the moving vehicle and the processor;

at least one first receiver for receiving first backscattered radar signals resulting from the first radar signals from the area of interest, the at least one first receiver being operatively associated with the moving vehicle and the processor;

at least one second transmitter for emitting second radar signals in a second direction, substantially opposite to the first direction, towards the area of interest, the at least one second transmitter being operatively associated with the moving vehicle and the processor;

at least one second receiver for receiving second backscattered radar signals resulting from the second radar signals from the area of interest, the at least one second receiver being operatively associated with the moving vehicle and the processor,

a GPS subsystem for providing position data relating to the position of the vehicle;

the GPS subsystem, the at least one first receiver and the at least one second receiver operating to provide position and radar data to the at least one processor to form a combined image of the area of interest;

the at least one processor operating to combine image data derived from the first backscattered radar signals with image data derived from the second backscattered radar signals to form a combined image of the area of interest containing sizes, shapes and relative locations of objects in the area of interest; and

a display to display the combined image.

2. The system of claim 1, wherein the wherein the first direction is a forward direction, the second direction is a rearward direction, and wherein the first transmitter transmits first radar signals in a forward direction into the area of interest and the second transmitter thereafter transmits second radar signals in a rearward direction into the area of interest as the moving vehicle travels forward, and wherein the first and second backscattered radar signals in combination with position data from the GPS subsystem form a combined image of the area of interest as the vehicle is moving.

3. The system of claim 1 wherein at lost one first transmitter emits first radar signals in a direction substantially forward of the moving vehicle and the at least one second transmitter emits second radar signals in a direction substantially backwards of the moving vehicle;

and wherein the at least one first receiver receives backscattered signals and the at least one second receiver receives backscattered signals;

each of the at least one first transmitter and the at least one second transmitter feeding first and second signals, respectively, to the at least one first receiver and the at least one second receiver, respectively, and wherein the first and second signals are different from one another.

4. The system of claim 3 wherein the first transmitted signals are transmitted by a first transmitter and received by a first array of first receivers and second transmitted radar signals are transmitted by a second transmitter and received by a second array of second receivers such that the radar signals are transmitted by the first transmitter and received by the first array at different time intervals than the second transmitter transmits and the second array receives radar signals.

5. The system of claim 3 wherein the at least one transmitter emits first signals over an angle less than or equal to 180 degrees and wherein the at least one second transmitter emits second signals over an angle less than or equal to 180 degrees in the opposite direction.

6. The system of claim 1 wherein the system is an ultra-wide, impulse-based synthetic aperture radar system with down-range resolution provided by the transmission of the first and second pulses within a wide frequency range and wherein each of the at least one first and second receivers comprises an array of antennas and wherein cross range resolution is provided by both the array of antennas and the synthetic aperture generated by the moving vehicle.

7. The system of claim 1, wherein the each of the at least one first transmitter and the at least one second transmitter comprises at least one transmitting antenna and wherein each of the at least one first receiver and the at least one second receiver comprises an array of at least our receiving antennas.

8. The system of claim 7 wherein each of the at least one first receiver and the at least one second receiver comprises a first and second array of antennas, respectively, and wherein the first array of antennas receives signals over an angle less than or equal to 180 degrees and wherein the second array of antennas receives second signals over an angle less than or equal to 180 degrees in the opposite direction.

9. The system of claim 8, wherein each of the antennas within each of the first and second arrays are positioned equidistant from one another in a semicircular array pattern.

10. The system of claim 1, wherein each of the at least one first and second transmitters transmit pulses within a wide frequency hand and wherein a down-range resolution is provided by a total bandwidth of the transmitted pulses, and wherein a cross-range resolution of said system is provided by the at least one first and second receivers and the motion of the vehicle, and wherein the at least one processor performs data processing on the image data including removal of interference, motion compensation, and filtering.

11. A method for investigating an area of interest using a radar system comprising:

mounting a radar antenna array on a vehicle moving in a forward direction;

transmitting a first group of signals in a forward direction and receiving a corresponding first group of backscatter signals from the radar antenna array for forming forward image data of the area of interest;

transmitting a second group of signals in a backward direction as the vehicle moves forward and receiving a second group of backscatter signals from said radar antenna array for forming rearward image data of the area of interest;

measuring a radar position of said radar platform;

processing the first group of backscattered signals to produce forward image data second group of signals to produce rearward image data;

combining the forward and rearward image data to form a combined image;

the combined image revealing the sizes, shapes, and relative locations of targets in the area of interest with respect to other objects in the area of interest; and

displaying the combined image.

12. The method of claim 11 wherein the forward and rearward image data contain overlapping data relating to the area of interest and further comprising the step of receiving GPS position data relating to the position of the vehicle using a GPS subsystem and wherein the combined image is any of a 2-D and 3-D image and wherein the radar system is synthetic aperture radar system.

13. The method of claim 11, wherein the radar antenna array includes a first group of antenna elements including at least one transmitting element and a plurality of receiving elements and a second group of antenna elements including at least one transmitting element and a plurality of receiving elements.

14. The method of claim 13, wherein the vehicle is one of an aerial or ground vehicle and wherein each of the transmitting elements includes a transmitter and a transmitting antenna and each of the receiving elements includes a receiver and a receiving antenna.

15. The method of claim 14, wherein each of the receiving, elements are positioned in a circular array and separated equidistantly to receive signals from a wide range of directions.

16. The method of claim 11, wherein said processing said signals further includes:

performing data processing on said digital signals for the removal of interference, motion compensation, filtering, and forming SAR imagery.

17. A system for investigating and displaying an image of an area of interest comprising:

a moving vehicle;

at least one processor for producing an image of the area of interest;

at least one first transmitter thr emitting first signals substantially in a first direction, the at least one first transmitter being operatively associated with the moving vehicle and the processor;

at least one first receiver for receiving reflected signals resulting from the first radar signals striking objects in the area of interest, the at least one first receiver being operatively associated with the moving vehicle and the processor;

at least one second transmitter operatively for emitting second signals in a direction substantially opposite to the first direction, the second transmitted signals being distinguishable from the first transmitted signals, the at least one second transmitter being operatively associated with the moving vehicle and the processor;

at least one second receiver for receiving, reflected signals resulting from the second transmitted signals striking objects in the area of interest, the at least one second receiver being operatively associated with the moving vehicle and the processor,

a GPS subsystem for providing position data relating to the position of the vehicle;

the at least one first receiver and the at least one second receiver operating to provide separate image data to the at least one processor;

the at least one processor operating to combine image data from the at least one first receiver and the at least one second receiver with the position data to form a single image; and

a display to display the combined image data revealing the sizes, shapes, and relative locations of targets in the area of interest;

whereby the system is able to recognize objects in the area of interest when only one of the first or second transmitted signals reaches the object.

18. The system of claim 17 wherein the at least one first receiver and the at least one second receiver receive signals from opposite directions, and wherein the system is capable of capturing an image of the sizes and shapes of targets disposed at an angle relative to the flight path of an aircraft such that radar signals striking portions of the angularly disposed targets are deflected away from the at least first receiver;

and radar signals striking portions of the angularly disposes are reflected towards the at least one second receiver, and whereby by combining the images of the at least one first receiver and the at least one second receiver a complete representation of the radar images of the detected targets in the area of interest is produced.

19. The system of claim 17 wherein at least one first transmitter emits first radar signals in a direction substantially forward of the moving vehicle and the at least one second transmitter emits second radar signals in a direction substantially backwards of the moving vehicle, and whereby the at least one first transmitter and the at least one first receiver comprise a forward looking sub-system and the at least one second transmitter and the at least one second receiver comprise a backward looking subsystem, and by combining the images resulting from the forward-looking and backward-looking sub-systems a complete representation of the radar images of the detected targets in the area of interest is produced.

20. The system of claim 17 wherein the at least one first receiver receives backscattered signals when the first radar signals strike a target in the area of interest and the at least one second receiver receives backscattered signals when the second radar signals strike the target as the vehicle moves past the target;

each of the at least one first transmitter and the at least one second transmitter feeding first and second signals, respectively, to the at least one first receiver and the at least one second receiver, respectively.