SYSTEMS AND METHODS FOR PRODUCING RADAR IMAGES

• US 20100097265A1
• Filed: 10/16/2008
• Published: 04/22/2010
• Est. Priority Date: 10/16/2008
• 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: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Inventors: HUEBSCHMAN, BENJAMIN D.
• Granted Patent: US 7,928,901 B2
• Time in Patent Office: Days
• US Class Current: 342/179
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
• CPC Class Codes: G01S 7/282 Transmitters

Abstract

Systems and methods for producing radar images are provided. In illustrated embodiments, a representative system includes: a transmitter operative to transmit a pulsed signal; a receiver operative to sample the pulsed signal after reflection; a Doppler-shifting mechanism operative to create a Doppler shift in the pulsed signal; and a platform upon which the transmitter and the Doppler-shifting mechanism are mounted, the Doppler shift being associated with relative motion between the Doppler-shifting mechanism and the platform.

Claims

1. A system for producing radar images, comprising:

a transmitter operative to transmit a pulsed signal;

a receiver operative to sample the pulsed signal after reflection;

a Doppler-shifting mechanism operative to create a Doppler shift in the pulsed signal; and

a platform upon which the transmitter and the Doppler-shifting mechanism are mounted, the Doppler shift being associated with relative motion between the Doppler-shifting mechanism and the platform.

2. The system of claim 1, further comprising an imaging unit operative to receive information corresponding to a plurality of samples from the receiver, determine respective frequency responses for the plurality of samples, and correlate the frequency responses into points on an illuminated target in order to produce an image.

3. The system of claim 1, wherein the platform is stationary during transmission of the pulsed signal.

4. The system of claim 1, wherein the Doppler-shifting mechanism is operative to rotate the transmitter with respect to azimuth.

5. The system of claim 1, wherein the Doppler-shifting mechanism is operative to vibrate the transmitter.

6. The system of claim 5, wherein the transmitter is operative such that the pulsed signal is timed to coincide with a peak in a vibration imparted to the transmitter.

7. The system of claim 1, wherein the Doppler-shifting mechanism comprises a concave reflector operative to reflect the transmitted pulse in the inertial plane of the concave reflector.

8. The system of claim 1, wherein the Doppler-shifting mechanism comprises a reflective rotating dish having an outer rim, the Doppler-shifting mechanism being operative to direct a pulsed signal from the transmitter to illuminate the outer rim such that the pulsed signal is transmitted in the inertial reference plane of the rotating dish.

9. The system of claim 1, wherein the transmitter is operative to maintain phase coherence between pulses.

10. A method of producing radar images, comprising:

transmitting a Doppler-shifted pulse;

receiving the Doppler-shifted pulse as a reflection from a target;

analyzing the pulse received to generate a plurality of samples; and

correlating frequency responses of the plurality of samples with points on the target.

11. The method of claim 10, wherein correlating frequency responses further comprises:

sorting the plurality of samples into range bins based on times received;

determining the frequency responses of the plurality of samples within the range bins;

correlating a frequency response of a sample to an azimuthal coordinate, and the range bin of a sample to a radial coordinate; and

producing an image of the target using the coordinates determined for the plurality of samples.

12. The method of claim 10, wherein pulse is transmitted from a wide-beam antenna that illuminates the entire target.

13. The method of claim 12, wherein the target is terrain.

14. The method of claim 10, wherein transmitting a Doppler-shifted pulse comprises imparting relative motion between the target and a transmitter used for transmitting the pulse.

15. The method of claim 14, wherein imparting relative motion comprises vibrating the transmitter.

16. The method of claim 15, further comprising timing transmission of the Doppler-shifted pulse to coincide with a peak in vibration of the transmitter.

17. The method of claim 14, wherein imparting relative motion comprises rotating the transmitter.

18. A method of producing radar images, comprising:

transmitting a Doppler-shifted pulse;

receiving the Doppler-shifted pulse as a terrain reflection;

analyzing the pulse received to generate a plurality of samples;

correlating the samples with range bins based on times received;

determining the frequency spectrum of for samples within the range bins; and

correlating the frequency spectra and the range bins with points on the terrain to produce an image of the terrain.

19. The method of claim 18, wherein the frequency spectra are correlated to azimuthal coordinates on the terrain.

20. The method of claim 18, wherein the transmitting and the receiving are performed on a non-moving vehicle.