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.
[1] 金添,孙鑫,李欣,等.SAR穿墙成像中墙体影响图像域补偿方法[J].电子学报,2012,40(7):1424-1428. Jin Tian,Sun Xin,Li Xin,et al.A method to compensate wall effects in the image domain for SAR through-the-wall imaging[J].Acta Electronica Sinica,2012,40(7),1424-1428.(in Chinese)
[2] Wang Gen-yuan,Amin M G.Imaging through unknown walls using different standoff distances[J].IEEE Transactions on Signal Processing,2006,54(10):4015-4025.
[3] Wang Gen-yuan,Amin M G,Zhang Yi-min.New approach for target locations in the presence of wall ambiguities[J].IEEE Transactions on Aerospace and Electronic Systems,2006,42(1):301-315.
[4] Dehmollaian M,Sarabandi K.Refocusing through building walls using synthetic aper ture radar[J].IEEE Transactions on Geoscience and Remote Sensing,2008,46(6):1589-1599.
[5] Solimene R,Soldovieri F,Prisco G,et al.Three-dimensional through-wall imaging under ambiguous wall parameters[J].IEEE Transactions on Geoscience and Remote Sensing,2009,47(5):1310-1317.
[6] Jin Tian,Chen Bo,Zhou Zhi-min.Imaging-domain estimation of wall parameters for autofocusing of through-the-wall SAR imagery[J].IEEE Transactions on Geosci ence and Remote Sensing,2013,51(3):1836-1843.
[7] Protiva P,Mrkvica J,Machac J,et al.Estimation of wall parameters from time-dela y-only through-wall radar measurements[J].IEEE Transactions on Antennas and Propagation,2011,59(11):4268-4278.
[8] 王芳芳,张业荣.基于支持向量机的电磁逆散射方法[J].物理学报,2012,61(8):084101-084208. Wang Fang-fang,Zhang Ye-rong.An electromagnetic inverse scattering approach ba sed on support vector machine[J].Acta Physica Sinica,2012,61(8):084101-084208. (in Chinese)
[9] Wang Fang-fang,Zhang Ye-rong.The support vector machine for dielectric target detection through a wall[J].Progress in Electromagnetics Research Letters,2011,23:119-128
[10] Gazdag J.Wave equation migration with the phase-shift method[J].Geophysics,1978,43(7):1342-1351.
[11] Olofsson T.Phase shift migration for imaging layered objects and objects immersed in water[J].IEEE Transactions on Ultrasonics,Ferroelectrics,and Frequency Control,2010,57(11):2522-2530
[12] Gu Xiang,Zhang Yun-hua.Autofocus imaging simulation for through-wall radar by using FDTD with unknown wall characteristics[A].Proceeding of Asia-Pacific Mi crowave Confeerence[C].Yokohama:IEEE,2010.1657-1660.
2016, Vol. 44 
