Azimuth Blur Suppression Method for SAR Sub-aperture Imaging

Abstract

The invention provides a method for suppressing azimuth ambiguity of synthetic aperture radar(SAR) sub-aperture imaging. The method is characterized by including the following steps of step1, subjecting range direction processing to raw echoed data according to the imaging processing flow and then dividing the sup-aperture along the azimuth direction, wherein the range direction processing of raw echoed data specifically includes implementing range direction fast fourier transform(FFT); implementing range compressing; implementing range direction inverse fast fourier transform(IFFT); removing pulse duration points; step2, subjecting range direction processing to sub-aperture after the data processing is completed, the range direction processing of sub-aperture includes the specific steps of firstly implementing sub-aperture azimuth FFT; zero filling the data at both ends and increasing pulse duration points at both ends to realize the expansion of sub-aperture length; implementing range direction FFT; implementing range direction inverse compression, cubic phase filtering and reference point phase compensation; implementing range direction IFFT; implementing Chirp Scaling algorithm.

Description

technical field [0001] The invention relates to an azimuth blur suppression method for SAR sub-aperture imaging, belonging to the technical field of SAR imaging. Background technique [0002] In the sub-aperture imaging processing, the spectrum of the azimuth signal is mainly represented by the quadratic phase term, including the Doppler signal that determines the azimuth resolution, and the quadratic term related to the range migration term. Azimuth ambiguity is caused by a quadratic term related to the distance migration term. The reference function of range migration correction (RCMC) behaves as a chirp signal along the azimuth direction, and the bandwidth is smaller than PRF. In the azimuth frequency domain, the signal does not meet the requirements of the sampling theorem, and the correction reference function will appear aliasing, which will lead to azimuth ambiguity appear. The distance between the azimuth ambiguous position and the true position of the target is th...

AI Technical Summary

Problems solved by technology

[0003] Regarding the suppression of azimuth ambiguity, there are two methods, one is to eliminate the aliasing of the range migration correction reference function, which can be done by increasing the length of the sub-aperture signal; since the range migration correction reference function The bandwidth is still smaller than the Doppler bandwidth, so this method cannot achieve the purpose of complete suppression of azimuth ambiguity

The other is to use the sub-aperture overlapping method to suppress the azimuth ambiguity, but this method will greatly increase the amount of storage and calculation of imaging processing

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