Diving movement high squint SAR sub aperture imaging space variance correction method based on two-stage filtering

Abstract

The invention belongs to the field of radar signal processing and discloses a diving movement high squint SAR sub aperture imaging space variance correction method based on two-stage filtering. An imaging geometric model is established, an original echo signal is subjected to range Fourier transform, a range walk correction and acceleration compensation function is constructed, and preprocessing is achieved. Then a compensated signal is transformed into a two-dimensional frequency domain, a first-order frequency domain filter factor is constructed to correct the space variance of a range envelope, a signal which is subjected to range direction process is transformed into an azimuth two-dimensional time domain through reverse Fourier transform, a high-order phase compensation function is constructed, then the compensated signal is transformed into an azimuth frequency domain, a second-order frequency domain filter factor is constructed to correct the space variance of azimuth Doppler parameters, a corrected signal is transformed into an azimuth time domain, and an azimuth unified compensation factor is constructed to implement the azimuth processing. Finally, a signal which is subjected to the azimuth processing passes an FFT to obtain the azimuth frequency domain to improve an 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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