Improved double-base synthetic aperture radar NLCS imaging algorithm

Abstract

The invention provides an improved double-base synthetic aperture radar NLCS (Nonlinear Chirp Scaling) imaging algorithm. The improved double-base synthetic aperture radar NLCS imaging algorithm comprises the following specific steps: firstly, calculating a cubic phase phi 3 of range direction of a target echo, selecting a reference point, acquiring a cubic phase phi'3 at the reference point according to the phi 3 and then multiplying the target echo by the conjugation of phi'3 at the reference point in a two-dimensional frequency domain to obtain a signal for eliminating the influence of high-order phase; secondly, multiplying the processed signal in the first step by a disturbing function phi in a range Doppler domain and multiplying the multiplied result by a matched filter phi R in the two-dimensional frequency domain; thirdly, converting the processed signal in the second step to a two-dimensional time domain to be multiplied by a direction distribution function phi 4, then multiplying the multiplied result and a matched filter phi 5 in the range Doppler domain and finally multiplying the multiplied result and phi 6 in the two-dimensional time domain to obtain an SAR (Synthetic Aperture Radar) slope-distance image; and fourthly, carrying out geometric rectification on the SAR slope-distance image acquired in the third step to obtain an SAR ground range image. According to the improved double-base synthetic aperture radar NLCS imaging algorithm, the influence generated by the two-dimensional spatial variability of the range tuning frequency and high-order phase when a sender is seen obliquely is improved.

Description

technical field [0001] The invention relates to an improved bistatic synthetic aperture radar NLCS imaging algorithm, which belongs to the technical field of synthetic aperture radar data processing. Background technique [0002] Compared with monostatic radar, bistatic radar has the advantages of flexible configuration, rich information acquisition, anti-interception and anti-interference due to the special configuration of bistatic radar. These advantages and application prospects have made bistatic radar more and more popular in recent years. favor. Bistatic radar includes many configuration modes, which are classified according to the type of transceiver platform, mainly including spaceborne bistatic SAR, airborne bistatic SAR, star-based bistatic SAR, ground-based bistatic SAR, etc. [0003] In the fixed mode of two bases and one station, the relative position of the transceiver changes with time, so the Doppler histories of targets at different azimuth positions are d...

AI Technical Summary

Problems solved by technology

However, when the transmitter operates in squint mode, the quadratic model fails when using the stationary phase principle to convert the signal from the two-dimensional frequency domain to the range-Doppler domain

This traditional NLCS algorithm not only ignores the range high-order phase introduced by the failure of the quadratic model in the stationary phase principle when the transmitter squints, but also does not consider the two-dimensional space-variation of the range modulation frequency.

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