Research On Target Location Method Of Urban Non-Line-of-Sight Blind Area

Non-line-of-sight blinded targets refer to targets that are located in the blind area of radar detection due to the occlusion of buildings.Such targets are common in urban environments.Therefore,the detection of such targets plays an important role in anti-terrorism,urban fighting,target rescue and automatic driving.Compared with electromagnetic transmission propagation,the attenuation of electromagnetic energy of multipath propagation is less,which is more suitable for target detection.At the same time,there are more propagation paths available in urban environment so that the multipath detection technology can be used in lots of complicated urban environments.Therefore,multipath detection is useful in urban sensing.In this thesis,the theory of non-line-ofsight target detection based on multipath detection technology is studied.The main contents are as follows:Traditional electromagnetic transmission propagation has large attenuation of electromagnetic energy,so that it is difficult to detect the hidden targets.In contrast,multipath propagation has a small attenuation of electromagnetic energy,which is more conducive to target detection.At the same time,due to the diversity of electromagnetic wave propagation routes,multipath detection technology has strong environmental adaptability.Therefore,multipath detection technology has important research value in the field of urban environment blinded target detection.In this thesis,the theory of non-line-of-sight target detection based on multipath detection technology is studied.The main contents are as follows:1.To analyze the feasibility of detecting the hidden target in L-shaped scenario,the electromagnetic wave propagation model of single input single output radar is established based on the analysis of the electromagnetic propagation characteristics.Then,based on electromagnetic simulation software,the effects of changes in the relative position of radar and target on the distribution of multipath signals are analyzed.2.To obtain the position of single target in urban non-line-of-sight blind area,two methods which using the time-of-arrival of the echo are researched based on the electromagnetic wave propagation model of single input single output radar.First,a method of alerting the target area is researched.This method uses the time-of-arrival produced by the diffraction propagation to accurately obtain the area where the moving target is located.Then,a single target localization method is proposed,which uses the correlation between the times-of-arrival of multipath echo signals to achieve accurate positioning of moving single targets.3.To obtain the position of multi-target in urban non-line-of-sight blind area,two imagingbased multi-target positioning methods are researched,based on the inherent relationship and characteristics of multipath signals of the multipath-input-multipath-output radar.Firstly,a multitarget positioning method based on multi-imaging dictionary fusion is researched,based on the back-projection imaging algorithm.Then a multi-target localization method based on the correlation of the multi-path ghosts in the image domain is proposed.This method uses the internal connection of multi-path signals in the image domain to obtain the positions of the targets.The above-mentioned algorithms have been verified through simulation or experimental data,which proves the effectiveness of the algorithm to achieve accurate target positioning in in urban non-line-of-sight blind area.