Location And Imaging Of Multi-target For Through-the-wall Detecting Radar

Through-the-wall Detecting Radar (TWDR) is a new radar system, which can detect the blocked objects. It can be widely used in military, law enhancement and rescue areas. Locating or imaging of multiple targets is usually interested in these through-the-wall detecting requirements. Ghosts may occur in this situation, which can make the detecting interfered badly. The aim of the present paper is to do some research on this problem to solve it.The property of through-the-wall propagation of electromagnetic wave is studied, and a modal of the propagation is given, which is suitable for computation. A location algorithm is deduced according to the modal. The source of the ghosts in multi-target detecting is studied, the conditions of the occurrence of a ghost are studied under ideal assumption, and taking account of the estimate error of arrival time and the presence of clutters, respectively. Formulas are deduced to calculate the probability of the occurrence of a ghost at a particular point under these conditions. A measure of ghosts'occurrence with expect of the number of the ghosts is proposed. An analysis of several antenna arrays by this criterion is down, and a proposal of the arrangement of the antenna array is presented.Two classes of methods to erase ghosts are presented in locating. One is still methods and the other is dynamic methods. Still methods utilize redundant time (distance) information to reject wrong association, hence to erase ghosts. Distance threshold method is presented as an association method to erase ghosts statically, while back-time threshold method and time threshold method are proposed for the same purpose. Dynamic methods employ the rule of movement of real target to erase ghosts. An applying of joint probability data association (JPDA) is presented.A back-project imaging algorithm suitable for through-the-wall detecting is presented, in which time computation is modified taking account of the presence of wall, and amplitude weighting is employed considering objects in the near-field and the effect of wall, while the blur accompany with lack of antennae is depressed effectively. The distribution of imaging precision and scope available for imaging is studied as well as the ghosts in the imaging. Probability weighting imaging is proposed to erase ghosts.