Waveform warping for general frequency-modulated radar waveforms
| DWPI Title: Intelligence, surveillance, and reconnaissance (ISR) radar system used in remote sensing activities, has waveform generator that generates parametrized frequency-modulated (FM) waveform to output modified FM waveform to radar antenna |
| Abstract: Various technologies pertaining to motion compensation for radar systems using FM waveforms are described herein. A waveform generator outputs a parametrized, pulsed FM waveform to a radar antenna, whereupon the radar antenna emits pulsed electromagnetic (EM) radiation into a target area based upon the parametrized FM waveform. The parametrized FM waveform compensates for motion of a radar platform that includes the antenna. The parametrized FM waveform compensates for inter-pulse Doppler effects by introducing a time delay to a reference FM waveform, and compensates for intra-pulse Doppler effects by time dilating, or frequency-scaling, pulses of the reference waveform. The parametrized FM waveform can be generated by modifying the reference waveform based on first and second parameters, where the parameters are based upon motion of the radar platform and changes in echo return delay times from one pulse to another. |
| Use: Intelligence, surveillance, and reconnaissance (ISR) radar system used in remote sensing activities to identify information about objects or vehicle in target area. Uses include but are not limited to synthetic aperture radar (SAR) system, ground moving target indicator (GMTI) radar system, dismount moving target indicator (DMTI) radar system, wide area search (WAS) radar system, and inverse SAR (ISAR) system. |
| Advantage: The waveform generator generates general FM waveform sufficiently and quickly so that each pulse of pulsed radar is independently compensated for motion of the radar platform. The processing of echo returns of the radar signal to yield useful data is simplified. The SAR image exhibits greater signal-to-noise ratio than SAR image generated based upon an echo return of linear FM chirp from the target area. The time-dilation parameter is configured to correct for intra-pulse doppler effects caused by the motion of the radar platform relative to the target or surveillance radar program (SRP). The time-shift parameter can be phase-delay parameter that is configured to correct for inter-pulse doppler effects caused by motion of the radar platform relative to the target. |
| Novelty: The system has a radar antenna (104) mounted to an airborne platform that is flying over a scene, and outputs a parametrized FM waveform towards the scene. A waveform generator (106) generates the parametrized FM waveform for output by the radar antenna, by generating an FM waveform, modifying FM waveform based upon a first parameter which is based upon a velocity of the radar antenna relative to a reference point in a target area (110) of the scene being flown over by the airborne platform, and outputting the modified FM waveform to the radar antenna. The modified FM waveform is the parametrized FM waveform. An image of the scene is generated based upon the modified FM waveform outputted by the waveform generator. |
| Filed: 2/21/2017 |
| Application Number: US15438024A |
| Tech ID: SD 13902.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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