Research On ISAR Imaging Technology Of Aerospace Targets

Inverse synthetic aperture radar(ISAR)is a kind of radar which can obtain the high resolution image of moving target.it has the capability of working all day and all weather.It uses the relative motion between the radar and targets to synthesize large aperture,and can be able to obtain the elaborate images of non-cooperative moving target,such as satellite,missile and airplane.Aerospace target includes all kinds of spacecraft instrumentation and space target.With the development of aerospace technology,the diversity of the aerospace target are increasing,the distribution of the aerospace target are expanding and the threat level of aerospace target are raising.,which makes the environment of aerospace target more complicated.Study the ISAR imaging of aerospace target can get the information of target motion and the structural characteristic effectively,which supports the aerospace target recognition and the strategic warning.It is meaningful to research the ISAR imaging of aerospace target in terms of the safety of aerospace.This thesis mainly studies the ISAR imaging of aerospace target.The specific work is arranged as follow:Chapter 1 is the introduction.The research background and significance of aerospace target ISAR imaging are introduced firstly.Then,the research status of aerospace target ISAR imaging both at home and abroad are elaborated,and finally the main contents of this thesis are given.In chapter 2,The aim of this chapter is to study a method to simulate the ISAR radar echo of aerospace target.The characteristic of aerospace target ISAR imaging is analyzed firstly.A new method of echo simulation of aerospace target is proposed,which based on the Satellite tool kit(STK)software.In chapter 3,the ISAR imaging algorithm of micro-motion target is studied.In order to study the missile target of micro-motion,exactly the precession.A ISAR imaging system of micro-motion target is established.It emphatically analyzed the variation of the Doppler frequency of nutation target.A improved ISAR imaging algorithm for micro-motion target is proposed.In chapter 4,prediction of ISAR image plane of aerospace targets is researched.Rely on the ISAR echo simulation of aerospace target based on STK,The moving condition of the aerospace target on the track and the micro-motion of itself is studied to calculate the normal vector of the image projection plane.two imaging plane prediction methods——geometric projection method and Range-Doppler mapping method are researched.In chapter 5,the ISAR imaging methods of aerospace targets based on the optimal time selection are studied.The characteristic of aerospace ISAR echo is studied firstly,optimal imaging time selection methods based on the Doppler frequency spread estimation and the image contrast are studied in detail.A method which combined the Doppler frequency spread estimation and the image contrast is studied,which take the azimuth resolution and imaging quality into account.Chapter 6 is the conclusion,which summaries this thesis,and makes a prospect for the future research.