In order to solve two key problems in through-the-wall imaging which are ambiguities of wall parameters and real-time imaging simultaneously,a two step imaging procedure is presented in which firstly the wall parameters are estimated by support vector machine and then the targets behind the wall is located and focused by phase shift migration algorithm.The estimated method is introduced emphatically,and the influence of the size,the location,the shape,the number of the targets and the length of the wall,sampling interval,noise on the estimated wall parameters is mainly discussed.The results demonstrate that the method based on SVM(Support Vector Machine) has the advantages of high precision and low computational time.Finally,the performance of two step imaging procedure is tested by a practical case of through-the-wall imaging,the results show that the procedure can realize real-time imaging under unknown wall characteristics,and also a relatively satisfactory image focusing is obtained.
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