Study Of Airborne SAR Ground Moving Target Detecting And Imaging

Synthetic Aperture Radar(SAR)created from 1960 s,is widely developed in many military and civilian areas.Compared with other remote sensing measures,SAR can work all day and in all kinds of climates.And it is not disturbed by fog and rain.Because of the advantages of SAR,it plays an important role in national territorial surveying,terrain mapping and remote sensing.Among SAR,FMCW(Frequency Modulated Continuous Wave)SAR has the advantage of low consumption,light weight and small size.It has become the hot research area all over the world.For the application of SAR,the imaging of stationary targets can’t meet the practical needs sometimes.The detection and imaging of ground moving targets has become the hot research area.GMTI(Ground Moving Target Indication)has become an important developing direction in SAR signal processing.It has also become the focus issue.GMTI has great influence on military application.GMTI has the ability to detect ground moving targets.But it has a low location precession and can’t get a favorable focusing image.So the imaging and parameters estimation become an important area of SAR moving target research.Based on the single channel mini-SAR,this article has done some research on the GMTI and imaging of moving targets.The work has been carried out as follows:1.The geometrical model of stationary moving targets imaging is established and the signal model is deduced.Based on the principles of stationary moving targets imaging,the signal model of moving targets is deduced.Compared with the stationary targets,the characteristics of the moving target signal and the reasons are analyzed.The moving target styles classified by the across-track velocity and the phenomenon of velocity ambiguity are also introduced.2.Doppler filter method is used to realize GMTI.The method of energy balance filter is used to estimate the Doppler center.In order to diminish the range migration,averaging of the range bins and cut the azimuth bins are implemented.The azimuth matching function is constructed to realize the rough focusing and location of the moving target.The simulation and real data processing verify the effectiveness of this method.3.Aiming at the mini-SAR system,an improved algorithm of moving target imaging and parameters estimation based on Fr FT and Radon transformation is introduced.It can correct the remaining range curve to improve the precision of focusing.Based on the algorithm mentioned above,the influence of three order phase of azimuth slow time is analyzed and compensated.An algorithm based on azimuth velocity searching and Fr FT is proposed.The simulation and real data processing verify the effectiveness of the method.The experiments of this article are based on the real data processing.It has favorable application foreground and practical sense.