Research On Inverse Synthetic Aperture Radar Motion Compensation

Synthetic aperture radar is an important branch of radar system,and it plays an important role in both military and civilian applications.This thesis firstly studies the implementation principle,algorithm process and key steps of synthetic aperture radar and inverse synthetic aperture radar,and deeply study the motion compensation algorithm.Envelope alignment is the first step of ISAR motion compensation.Its essential principle is estimating the envelope offset parameters according to certain mathematical criteria,and perform cyclic shift in the time domain or frequency domain according to the estimated parameters to complete the alignment.Secondly,we propose a new method for evaluating the performance of envelope alignment,which can intuitively and quantitatively judge the pros and cons of different methods.In addition,it is found that the effect of the traditional method will decrease in the case of low signal-to-noise ratio through experiments.Considering the factors of noise,we propose improvement measures to the original method based on the non-stationarity measure.Finally,the effect of the proposed method is verified by experiments..The main innovations of this work are as follows:1.To accurately evaluate the performance of envelope alignment,this thesis proposes a performance evaluation method based on the offset residual sequence.The method calculates the sum of ₁L norm and the non-stationarity measure of the offset residual sequence as evaluation indicators,and judges the quality of the method accordingly.The experimental results show that this method can accurately compare different methods.2.This thesis proposes a new alignment method based on non-stationarity metrics.Inverse synthetic aperture radar will inevitably work in a complex environment because of its all-weather working characteristics.The effect of the traditional method will decrease when the noise is large.Since NS is not affected by the perturbation noise distribution,it can be well applied in the case of low signal-to-noise ratio.Therefore,we propose a new alignment method based on non-stationarity metrics,which can improve the accuracy of envelope alignment based on the original method.The experimental results show that the proposed method has improved performance compared with the original method.3.We design a simulation experiment on simulating ISAR multipoint imaging to verify the performance evaluation scheme of envelope alignment proposed in this thesis.Through experiments,the accuracy of the proposed evaluation method is verified,and the performance of various envelope alignment methods is analyzed and compared.Then,the imaging effects of the proposed method and various methods are compared through the actual measurement experiments.The experimental results show that the improved method has obvious improvement in the way of image entropy.