A large-width imaging method for satellite-based bistatic synthetic aperture radar in geosynchronous orbit

Abstract

The invention provides a large-width imaging method of a geosynchronous orbit star-machine bistatic synthetic aperture radar, which belongs to the technical field of synthetic aperture radar. The present invention first performs multi-channel simultaneous TOPS scanning to acquire echoes, and processes the received multi-channel echoes to remove under-sampling blur, solve rotation blur, and splicing to obtain a large and wide imaging result. Aiming at the large-scale coverage of the GEO irradiation source on the ground, the invention adopts the TOPS mode at the airborne receiving station to scan multiple surveying strips to record echoes, fully utilizes the irradiation range of the transmitting station, and expands the imaging range of the GEO star-machine dual-base SAR width. The present invention is characterized in that when processing the single-base TOPS echo in the double-base configuration, the multi-channel reconstruction technology and the TOPS processing method are combined to solve the under-sampling ambiguity and the rotation ambiguity in the SAR echo spectrum.

Description

technical field [0001] The invention belongs to the technical field of synthetic aperture radar, and in particular relates to a large-width imaging method of a geosynchronous orbit star-machine bistatic synthetic aperture radar. Background technique [0002] Synthetic Aperture Radar (SAR) is a high-resolution imaging radar with strong penetrability and all-weather and all-weather characteristics. At present, the technology is relatively mature and is widely used in the fields of earth remote sensing, resource exploration, topographic mapping, etc. . [0003] Geosynchronous Synthetic Aperture Radar (GEOSAR) has a synchronous orbit with an orbital height of about 36,000km, and its beam can cover the ground up to 280km. It has the advantages of short revisit period and wide observable range. Maintain continuous irradiation of the designated area within the range. [0004] Geosynchronous Spaceborne-Airborne Bistatic SAR (GEO BiSAR) uses the GEO SAR satellite as the illuminatio...

AI Technical Summary

Problems solved by technology

However, since the point target echo Doppler bandwidth of general GEO-BiSAR has exceeded the pulse repetition frequency (PRF) of the transmitting station, it will cause spectrum aliasing due to undersampling, resulting in undersampling ambiguity. In the prior art, A multi-channel technique for undersampling blur in GEO BiSAR is proposed

However, the echo spectrum received in TOPS mode will have Doppler centroid space variation, and the spectrum of targets at different azimuth points will occupy different frequency bands, resulting in the Doppler bandwidth in the entire scene far exceeding the PRF; General TOPS echo method to remove rotation blur

However, these methods are all aimed at the situation where the PRF is greater than the Doppler bandwidth of the point target. Once the PRF is lower than the Doppler bandwidth of the point target, the method will fail and cannot perform unambiguous imaging.

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