Spatial variation correction method for high squint SAR subaperture imaging based on two-stage filtering

Abstract

The invention belongs to the field of radar signal processing and discloses a two-stage filter-based high squint SAR sub-aperture imaging space-variation correction method, which establishes an imaging geometric model, performs range-to-Fourier transform on the original echo signal, and constructs a distance Walking correction and acceleration compensation function to achieve preprocessing; then transform the compensated signal to the two-dimensional frequency domain, construct the first-level frequency domain filter factor to correct the space variation of the distance envelope, and inverse the distance to the processed signal Fourier transform to azimuth two-dimensional time domain, construct high-order phase compensation function, then transform the compensated signal into azimuth frequency domain, construct second-level frequency domain filter factor to correct the spatial variation of azimuth Doppler parameters, The corrected signal is transformed into the azimuth time domain, and the azimuth uniform compensation factor is constructed to realize azimuth processing; finally, the azimuth processed signal is FFTed into the azimuth frequency domain to obtain the final SAR focused image to improve the azimuth focus depth.

Description

technical field [0001] The invention belongs to the technical field of radar signal processing, and in particular relates to a two-stage filter-based high squint SAR sub-aperture imaging space-variation correction method in a subduction section, which can be used for SAR imaging processing of a high-speed maneuvering platform. Background technique [0002] Synthetic Aperture Radar (SAR) can obtain two-dimensional high-precision images of the target area all day and all day long. The mobile platform SAR imaging technology that combines drones, helicopters and other mobile platforms with SAR has become the mainstay of radar imaging. An important research direction, it has been widely used in map surveying and post-disaster search and rescue. [0003] In SAR imaging, in order to ensure the maneuverability of the platform, it needs to work in the high squint mode; in order to ensure real-time observation, it is necessary to use sub-aperture for coherent processing to simplify th...

AI Technical Summary

Problems solved by technology

However, in the high squint dive mode, the existence of three-dimensional velocity and acceleration will lead to the failure of the traditional model. At the same time, the severe coupling of range and azimuth and the space variation of the squint angle along the range direction will lead to two-dimensional space variation of the range envelope and azimuth phase, which will seriously affect image quality

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