Synthetic aperture radar incorporating height filtering for use with land-based vehicles

• US 7,764,220 B1
• Filed: 04/22/2009
• Issued: 07/27/2010
• Est. Priority Date: 04/22/2009
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Samaniego, Raymond
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US12/428,280
• Time in Patent Office: 461 Days
• Field of Search: 342/22, 342/27, 342/25.R, 342 25 A- 25 F, 342/179
• US Class Current: 342/25.00A
• CPC Class Codes: G01S 13/4445 amplitude comparisons monopulse, i.e. comparing the echo signals received by an antenna arrangement with overlapping squinted beams
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 13/9092 combined with monopulse techniques

Abstract

According to one embodiment, a synthetic aperture radar includes an image former coupled to a pair of antennas that are oriented at differing elevational angles relative to one another. The antennas are configured in a land-based vehicle that moves horizontally relative to a target having one or more internal features. The image former receives signals from the antennas that are indicative of electro-magnetic radiation reflected from a target and generates images according to the signals. The image former then generates a final image by filtering the amplitude component of the imagery from a first antenna against the amplitude component of the imagery from a second antenna.

Claims

1. A synthetic aperture radar comprising:

an image former comprising instructions stored in a memory and executable on a computing system, the image former coupled to a first antenna and a second antenna that are adjacent to and oriented at differing elevational angles relative to one another, the first antenna and the second antenna configured in a land-based vehicle that is operable to move horizontally relative to a building having one or more internal features, the first antenna operable to transmit electro-magnetic radiation toward the building with a frequency in the range of 0.5 to 3.0 Giga-Hertz, the image former operable to;

receive a first signal having a first amplitude component from the first antenna and a second signal having a second amplitude component from the second antenna, the first signal and the second signal indicative of electro-magnetic radiation reflected from the building;

generate a first image according to the received first signal and a second image according to the received second signal; and

generate the third image by generating a height discriminant map comprising pixels corresponding to the first amplitude portions of the first image and the second amplitude pixels of the second image, and filtering the first image using the height discriminant map to form the third image.

2. A synthetic aperture radar comprising:

an image former comprising instructions stored in a memory and executable on a computing system, the image former coupled to a first antenna and a second antenna that are oriented at differing elevational angles relative to one another, the first antenna and the second antenna configured in a land-based vehicle that is operable to move horizontally relative to a target having one or more internal features, the image former operable to;

receive a first signal having a first amplitude component from the first antenna and a second signal having a second amplitude component from the second antenna, the first signal and the second signal indicative of electro-magnetic radiation reflected from the target;

generate a first image according to the received first signal and a second image according to the received second signal; and

generate a third image by filtering the second amplitude component of portions of the second image against the first amplitude component of corresponding portions of the first image, the first amplitude component and the second amplitude component indicative of an elevational deviation of the one or more internal features relative to the elevational angle of its respective antenna.

3. The synthetic aperture radar of claim 2, wherein the first antenna is operable to transmit the electro-magnetic radiation toward the target.

4. The synthetic aperture radar of claim 2, wherein the image former is operable to generate the third image by generating a height discriminant map comprising portions corresponding to the first amplitude portions of the first image and the second amplitude portions of the second image, and filtering the first image using the height discriminant map to form the third image.

5. The synthetic aperture radar of claim 2, wherein the land-based vehicle comprises a radome that is configured over a portion of a surface of the land-based vehicle, the radome operable to conceal the first antenna and the second antenna.

6. The synthetic aperture radar of claim 2, wherein the target comprises a building.

7. The synthetic aperture radar of claim 2, wherein the electro-magnetic radiation has a frequency in the range of 0.5 to 3.0 Giga-Hertz.

8. The synthetic aperture radar of claim 2, wherein the first antenna is configured adjacent to the second antenna.

9. The synthetic aperture radar of claim 2, wherein the portions of the first image and the second image comprise pixels of the first image and the second image.

10. The synthetic aperture radar of claim 2, wherein the land-based vehicle comprises a truck.

11. The synthetic aperture radar of claim 2, wherein the one or more internal features are selected from the group consisting of a doorway, a wall, a window, a metal box, a door, and a person.

12. An imaging method comprising:

receiving a first signal having a first amplitude component from a first antenna and a second signal having a second amplitude component from a second antenna that is oriented at a differing elevational angle relative to the first antenna, the first antenna and the second antenna configured in a land-based vehicle that moves horizontally relative to a target having one or more internal features, the first signal and the second signal indicative of electro-magnetic radiation reflected from the target;

generating a first image according to the received first signal and a second image according to the received second signal; and

generating a third image by filtering the second amplitude component of portions of the second image against the first amplitude component of corresponding portions of the first image, the first amplitude component and the second amplitude component indicative of an elevational deviation of the one or more internal features relative to the elevational angle of its respective antenna.

13. The imaging method of claim 12, further comprising transmitting, by the first antenna, the electro-magnetic radiation toward the target.

14. The imaging method of claim 12, wherein generating the third image comprises generating the third image by generating a height discriminant map comprising portions corresponding to the first amplitude portions of the first image and the second amplitude portions of the second image, and filtering the first image using the height discriminant map to form the third image.

15. The imaging method of claim 12, further comprising concealing, using a radome configured over a portion of a surface of the land-based vehicle, the first antenna and the second antenna inside the land-based vehicle.

16. The imaging method of claim 12, further comprising moving the first antenna and the second antenna horizontally with respect to a building.

17. The imaging method of claim 12, wherein receiving the first signal and the second signal comprises receiving the first signal and the second signal having a frequency in the range of 0.5 to 3.0 Giga-Hertz.

18. The imaging method of claim 12, further comprising receiving the first signal from the first antenna and the second signal from the second antenna that is adjacent to the first antenna.

19. The imaging method of claim 12, wherein the first antenna and the second antenna are configured in a truck that moves horizontally relative to the target.

20. The imaging method of claim 12, wherein generating the third image by filtering the second amplitude component of portions of the second image against the first amplitude component of corresponding portions of the first image comprises generating the third image by filtering the second amplitude component of pixels of the second image against the first amplitude component of corresponding pixels of the first image.