| By transmitting electromagnetic waves in a specific frequency band,the through-wall radar can penetrate through non-metallic obstacles such as walls,and receive echoes from concealed personnel to locate targets.At present,two methods of coordinate localization and image localization are mainly adopted;The results of the former are simple and clear,while the information of the latter is intuitive.Since through-the-wall Radar(TWR)localization system can be adopted in anti-terrorism war and urban alley station,it is worth paying attention to how to display the target conveniently and exactly.In this paper,we focus on the moving target localization behind the wall,covering several key technical problems of the moving target localization of TWR,including moving target localization based on distance-angle and moving target localization based on imaging.The main work and contributions of this paper are as follows:(1)Firstly,the advantages and disadvantages of the three ultra-wide band signal systems are compared,and the key parameters are designed and the one-dimensional distance image of the moving target is analyzed.Secondly,Secondly,the basic ranging principle equation of step frequency signal system radar is derived,the basic principle of angle measurement and the influence factors of angle measurement accuracy are analyzed,and the corresponding preparation is made for the "distance-angle" positioning algorithm proposed in subsequent chapters..Finally,the cause of gating lobe is analyzed,and the backward projection imaging algorithm of step frequency signal is deduced.It is pointed out that the images formed by each channel at the main lobe and grating lobe have different characteristics,which lays the foundation for the suppression of the grating lobe in the subsequent imaging domain.(2)Research on the localization methods based on "distance-angle".In this paper,a method of using step frequency triangular wave frequency modulation is proposed,which eliminates multiple square terms in mixing signal and realizes "distance-velocity" decoupling,so as to measure the distance of moving target.Based on this,the coordinate positioning equation based on one and two receiving radar is established,and the twodimensional localization of moving target is realized.Aiming at the need of future development,a new three-dimensional coordinate system is established,the two-dimensional localization algorithm is extended to threedimensional,and the three-dimensional localization algorithm based on one-shot and four-received radar is deduced,and the three-dimensional localization of moving target is realized.Finally,the algorithm is verified by Matlab simulation,and the moving target is precisely located.(3)Research on imaging-based localization methods.Aiming at the problem of introducing high gating lobe level with limited aperture length and limited number of array elements in through-the-wall radar array imaging,an array configuration method is proposed,which achieves higher resolution and lower gating lobe level.Firstly,the configuration method of the transceiver split MIMO array is analyzed,and the array can be designed according to the required gating level and resolution.In addition,the configuration method of transceiver co-located MIMO array is analyzed.When the number of current lines is more than 4,a superior array is designed by using the proposed method.Secondly,the paper analyzes the method of image domain suppressing gating lobe,which can effectively suppress azimuth gating lobe.Finally,the method is verified by Matlab simulation and measured data,and the moving target localization based on array imaging is realized.. |
PDF Full Text Request