Low-altitude Target Detection And Direction-of-arrival Estimation Based On Orthogonal MIMO Radar

Detection and parameter estimation of low altitude targets is one of the main problems faced in modern military radar.The main difficulties faced include: the jamming of changeable strong clutter,complicated electromagnetism environment and the strong maneuverability of targets,low RCS.All these characteristics cause obscure target easily each other,especially a weak target near strong target,which reduces the detection performance of radar.In this paper,we studied the low altitude targets detection algorithm and DOA estimation algorithm based on orthogonal MIMO radar.The main tasks include:The first chapter is introduction.First of all,we introduced research background and meaning.Then,we explained the present situation of MIMO radar.Then,we introduced some low altitude target detection methods and present situation in detail,and then,summarized some methods of improving detection performance for low altitude targets.Then,we introduced the present situation of DOA estimation technique in detail.Last but not least,we introduced research tasks and the architecture of this thesis.Then,we discussed the performance of the pulse compression technology and dechirp technology.Then,we got the advantage of dechirp technology,which reduce data sampling speed and data volume.The third chapter mainly studied low altitude targets detection method based on MIMO radar.Firstly,we studied the low altitude moving target detection(MTI+MTD)method.Then,on this basis,the Constant-False-Alarm(CFAR)detection algorithm of single channel was studied,which include four kind of one-dimensional CFAR algorithm and two kind of two-dimensional CFAR algorithm.From the simulation results,we can get the conclusion that single channel CFAR detector cannot detect the weak target nearly strong interference or target,and it is easy to cause the weak target to miss.The detectior performance degraded seriously.Secondly,the multi-channel target detection algorithm of MIMO radar was studied.Then,we proposed a multi-channel CFAR detector for low-altitude target based on orthogonal MIMO radar.Given the structure of the detector,proved the CFAR features of this detector.Finally,the performance of the detector was compared and analyzed.The fourth chapter mainly focuses on the Direction-of-Arrival estimation technology of orthogonal MIMO radar.Firstly,we introduced MIMO radar signal processing model and the properties of the fourth-order cumulant.After that,we studied three traditional DOA estimation algorithms,and compared the performance of each algorithm.Secondly,in order to overcome the shortcomings of traditional DOA estimation algorithms,low angular resolution.We proposed two fast CUM-m-Capon DOA Estimation Algorithms Based on Fourth-order Cumulant.One is mean dimension reduction technique.Another is projection transformation dimension reduction technique.Finally,the advantages and disadvantages of the two estimation algorithms are analyzed by matlab simulation,and verified the validity and robustness of the two DOA estimation algorithms on the measured data sets.The fifth chapter makes a summary of the main work and innovation of the full text.Finally,proposing the future research expectation.