Research On Ground Moving Target Location Method Based On Unknown Wave Velocity

Ground moving target positioning technology has a broad application prospect in both military and civilian fields.In the military field,the length of China’s land border is about 22,000 kilometers,and the border area is complicated with few natural barriers and difficult control.The use of ground target positioning technology can provide effective means for border security protection and significantly reduce labor costs.In the civil field,it can be used for cultural relics protection,prison protection,base station and other key areas of security,to effectively protect the security of national people’s property.At present,ground moving target detection and further classification recognition based on vibration have been relatively mature.However,due to the complex and irregular geological environment,the accurate location of ground moving targets is still a big problem.TDOA positioning algorithm has been widely used due to its advantages of high positioning accuracy and easy implementation.However,in the past TDOA positioning,most of the vibration signal propagation speed is regarded as a known constant,which does not conform to the actual conditions such as complex geological conditions and environmental temperature changes.To solve this problem,this paper proposes a non-iterative algorithm for unknown wave velocity location.The main research contents are as follows:1.In this paper,vibration signals generated by walkers are taken as the research objective.Firstly,the amplitude-frequency characteristics of the original vibration signals collected are studied,and the environmental background noise in the signals is filtered by wavelet threshold denoising method according to the characteristics of the signals.The root-mean-square error and signal-to-noise ratio were used as evaluation indexes to select the optimal denoising parameters.2.In view of the problems of poor accuracy and difficulty in searching spectral peaks of previous delay estimation algorithms at low signal-to-noise ratios,a generalized cross-correlation delay estimation method with improved weighting function is adopted in this paper to generate mixed signals at different signal-to-noise ratios by superimposing noise from relatively pure vibration signals.Simulation experiments are conducted to verify the estimation performance of this delay estimation method at different signal-to-noise ratios.3.Through literature summary and field velocity test experiment,it is concluded that the assumption of constant vibration velocity is not consistent with the actual situation.In order to solve this problem,a non-iterative unknown location algorithm of wave velocity is proposed,which takes the vibration signal propagation speed as unknown variable,calculates the vibration signal propagation speed in real time and realizes the preliminary estimation of the target.Then Taylor series expansion method is used to further optimize the location results to achieve accurate location of ground moving targets.4.Build a multi-sensor signal acquisition and positioning system to collect vibration signals generated by pedestrians,and write functional programs for data acquisition and storage,time delay estimation and target location based on Lab VIEW platform.Select an experimental site for field experiments to verify the performance of non-iterative unknown wave velocity location algorithm.And the selection of the relative coordinate system,the change of the number of sensors and speed selection strategy and other aspects of the experimental research,analysis of the experimental results,and finally the factors that may lead to positioning error were summarized.