Research On Multipath Ghosts Suppression And Target Extraction Method Of Through-wall Imaging Radar

Through-wall radar detection is to detect and locate targets behind the wall by transmitting low-frequency electromagnetic wave signals.It has broad prospects in the military and civilian fields and has developed rapidly in recent years.When electromagnetic waves propagate in a complex wall environment,physical phenomena such as reflection,refraction,and transmission can occur,and the transmitted signal will have amplitude attenuation and time delay.Conventional through-wall radar detection models are based on a front wall.However,when the back wall exists,electromagnetic waves penetrate the wall and multipath reflection can occur on the inner surface of the back wall.Multipath ghosts are introduced in the through-wall radar image.It is difficult to extract targets at the background of wall clutter.When both side walls are present,multipath ghosts of the left and right side walls will be generated due to the multipath effect of electromagnetic waves,which will interfere with the detection of the target.This article has carried out related research on the above issues,and the specific research contents are as follows:(1)The clutter and the multipath ghosts generated by the target and the back wall seriously interfere with the target extraction in through-wall radar imaging.Through singular value decomposition(SVD)of radar echo signal,the interference of wall clutter can be effectively suppressed,but the multipath ghosts cannot be eliminated.In order to solve this problem,a target extraction method based on SVD and binary image fusion is proposed.Based on the difference of image region attributes between the target and multipath ghosts,the binary image of only the target is fused with the radar image after SVD to obtain the high-precision target image.The data processing results of the simulation experiment show that the target image can be extracted accurately and the target-to-clutter ratio(TCR)is improved significantly.(2)In the through-wall radar imaging,the multipath ghosts and clutter can generate due to the reflection between the side wall and the target and the back wall,which seriously interferes with the target detection and imaging.In this paper,We firstly establish the scene model of such ghosts and clutter and construct the multipath propagation model between the target and the wall.Based on this,we give the basic criteria of selecting sub-apertures.Then,based on the principle of sub-apertures image multiplication,a gamma correction method is proposed.That is,each sub-image index weight is obtained according to the proportional relationship of image contrast.And weighted sub-images are multiplied,which achieves the effect of suppressing multipath ghosts and strong clutter.Finally,experimental simulation and corresponding analysis are given,and the target-to-clutter ratio is significantly improved.