Imaging Algorithm And Realization Of FMCW SAR

Frequency modulated continuous wave synthetic aperture radar(FMCW SAR)is a new imaging radar system which combines frequency modulation continuous wave technology and synthetic aperture technology.It has the advantages of small size,light weight,low power consumption,high resolution and so on.And because SAR imaging affected by the outside world such as light and weather conditions are relatively small,coupled with its low cost and the penetrating imaging capability,makes the FMCW SAR can be widely used in fields of environmental monitoring,resource exploration,disaster relief etc.High resolution imaging is one of the key problems to be solved in FMCW SAR.Therefore,based on the pulse SAR,this thesis studies the high resolution imaging algorithm for FMCW SAR.In the thesis,the principle of synthetic aperture is studied,and the method for ensuring high azimuth resolution is obtained.And then the principle of dechirp is studied.After the dechirp processing,on the one hand the request of the sampling rate can be reduced.On the other hand,the signal after dechirp processing is no longer linear frequency modulation signal,but a signal of constant frequency,which will greatly simplify the signal processing in range direction.On this basis,combined with the geometric model of FMCW SAR,the echo model of FMCW SAR system is deduced.Based on the original range-Doppler(RD)imaging algorithm for FMCW SAR,adding the processing of elimination RVP,an improved RD algorithm for side-looking strip-mode FMCW SAR is proposed in the thesis which can improve imaging resolution.A kind of RD algorithm for strabismus FMCW SAR is also put forward in the thesis.By analyzing the frequency scaling process and its influence,the thesis has put forward improvement schemes respectively for FS algorithm of side-looking and squint mode FMCW SAR.Finally,the thesis has analyzed the influence of the radar departure from ideal track,and proposes an algorithm combining the motion compensation technique with the imaging algorithm to solve the problem of high resolution imaging of radar under non uniform linear motion.The effectiveness and availability of the proposed improved algorithms are verified by experiments.