SAR ground moving target imaging method based on sub-aperture parameter estimation

Abstract

The invention belongs to the technical field of radar, and discloses an SAR ground moving target imaging method based on sub-aperture parameter estimation. The method comprises the following steps: dividing original echo data into sub-aperture echo data and establishing a full-aperture instantaneous pitch model and a sub-aperture distance frequency domain echo data model on the basis of assumptions of target maneuvering motion in a full-aperture CPI and uniform motion of a target in a sub-aperture CPI; estimating parameters of the sub-aperture echo data; calculating a full-aperture instantaneous Doppler frequency vector by using the echo data parameters; obtaining a full-aperture instantaneous Doppler frequency vector model by using the full-aperture instantaneous pitch model; substitutingthe instantaneous Doppler frequency vector into the instantaneous Doppler frequency vector model; solving a coefficient to be determined, and correcting a high-order phase error of the full-apertureoriginal echo data by using the coefficient to be determined, thereby greatly improving the focusing level of a moving target under a large squint SAR imaging mode and obtaining images with better quality.

Description

technical field [0001] The present invention relates to the field of radar technology, in particular to a synthetic aperture radar (English full name: Synthetic Aperture Radar, English abbreviation: SAR) ground moving target imaging method based on sub-aperture parameter estimation. Background technique [0002] SAR was originally mainly used to image static ground scenes, but in special applications such as traffic detection and battlefield awareness, people are more interested in ground moving targets. However, due to its unknown motion parameters, ground moving targets introduce high-order phases into SAR echo data, and SAR imaging processing for static scenes cannot remove the high-order phases in echo data, resulting in ground moving targets appearing in SAR images Unable to focus, which brings difficulties to the subsequent recognition and classification of moving targets based on SAR images. In order to solve this problem, the SAR ground moving target imaging process...

AI Technical Summary

Problems solved by technology

However, this method still has shortcomings: since this method is designed for the front-looking and side-looking working mode, and the SAR echo in the front-looking and side-looking working mode does not need high-order phase correction, this method cannot be directly applied to high squint SAR Echo Data Processing of Moving Target

However, the disadvantage of this method is that the full-aperture imaging process is adopted, and it is assumed that the ground moving target moves at a uniform speed within the full-aperture coherent processing interval (English full name: Coherent Process Interval, English abbreviation: CPI). Due to the long full-aperture CPI , resulting in a difference between the hypothesis and the actual motion of the target, so it cannot effectively correct the third-order or higher phase error in the echo data of the moving target, and eventually the image quality will be poor due to insufficient focus

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