Spaceborne Ultra-High Resolution Sliding Spotlight SAR Imaging Method

Abstract

The invention provides a spaceborne ultrahigh-resolution sliding bunching SAR (synthetic aperture radar) imaging method. The technical scheme includes: firstly, dividing full aperture data obtained in one-time observation of spaceborne sliding bunching SAR into a plurality of sub-apertures, and respectively establishing a local linear aperture distance process model under the sub-aperture at each sub-aperture; secondly, subjecting each piece of sub-aperture data to sub-aperture focusing processing and simultaneously compensating inconformity of focusing positions and phase positions caused by piecewise linear aperture distance processes; and finally, synthesizing each piece of sub-aperture data into full aperture data, and solving the problem of azimuth shift caused by large azimuth swath width through nonlinear frequency modulation de-rotating to finally realize imaging. Compared with existing methods, the spaceborne ultrahigh-resolution sliding bunching SAR imaging method has the advantages that calculated amount is not increased too much, and high efficiency of calculation is maintained.

Description

Technical field [0001] The invention belongs to the cross-technology field of aerospace and microwave remote sensing, and particularly relates to an imaging processing method for a new working mode of spaceborne SAR (Synthetic Aperture Radar)-Sliding Spotlight Synthetic Aperture Radar (Sliding Spotlight Synthetic Aperture Radar). Background technique [0002] The working mode of the spaceborne sliding spotlight SAR is a novel SAR working mode between the strip mode and the spotlight mode. The azimuth resolution is controlled by controlling the moving speed of the antenna irradiation area on the ground. The imaging area is larger than the spotlight SAR, and the resolution is higher than the strip SAR of the same antenna size. Under the premise of a small reduction in resolution, spaceborne sliding spotlight SAR can obtain a larger azimuth imaging band width than spotlight SAR, and makes a good trade-off between high resolution and large area imaging; at the same time, the antenna ...

AI Technical Summary

Problems solved by technology

When the resolution is high enough, on the one hand, the ultra-long synthetic aperture corresponding to the spaceborne sliding spotlight SAR causes nonlinear aperture problems. If the current distance history based on linear aperture is still used to process data, it will lead to serious azimuth defocusing ; On the other hand, the problem of azimuth and direction shift of the azimuth matched filter under high resolution is highlighted, and the existing BAS algorithm uses the derotation processing of the fixed chirp frequency, which cannot adapt to the azimuth and direction shift of the azimuth modulation frequency, resulting in The imaging quality of the area azimuth to the edge decreases significantly

These problems cannot be solved by all existing spaceborne sliding spotlight SAR imaging algorithms including the sub-aperture BAS algorithm.

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