Research On Localization Error Around The Corner In Multistatic Radar System

In the environment of anti-terrorism,commandos need to embark on terror-controlled neighborhoods or urban areas.Unknown terrorists on the corner of the street may suddenly appear and attack the anti-terrorist commandos.Detecting the distribution of terrorists around the corners can greatly reduce the casualties of the commandos.However,corner is a more complex reflection of the environment,which covers lots of dead ends of detection.The Multi-static radar system with independent transmitter and receivers can cover those dead ends as much as possible.The research on localization of target around the corner by multi-static radars involves problems of the regional convergence characteristics of multi-static radar localization methods,the influence of range measurements with great errors,the removal of false points,and non-line-of-sight location method.On the above issues,the job of this paper can be summarized as follows:1.The region convergence of iterative positioning methods applied in the multi-static radar system was studied,which can give reference to the distribution of radars.Firstly,a variety of iterative localization principles such as the Levenberg-Marquart method,the Gauss-Newton method and the Tailor series method were discussed,which gives the theoretical basis to multi-static radars positioning.Secondly,the CRLB(Cramer-Rao lower bound)of the coverage area of the signal of the multi-static radars was studied which gives the distribution characteristics of the positioning accuracy in the area covered by the radar.Finally,a variety of iterative localization methods were simulated for the radar coverage area and analyze the convergence characteristics of each positioning method was analyzed.In the radar coverage area,different iterative methods have different regional convergence distributions,showing different convergence shapes.2.To improve the positioning accuracy of multi-static radars,the range measurement errors of multi-static radars were studied,and the residual algorithm was used to eliminate the influence of radar with big ranging error.Firstly,the relationship between the residual errors of ranges and the ranging errors of multi-static radars was analyzed.This relationship is found approximately linear.Depending on the distance residual,the distance measurement error can be determined.This feature gives the basis for the feasibility of residual algorithm.Secondly,the principle of residual algorithm was introduced to eliminate the radar station with large ranging errors.Finally,simulation and experiment are given to compare the residual algorithm with other methods.In this experiment,more than one radar stations with big ranging errors were removed,and the positioning accuracy was improved.Compared with other methods,the residual algorithm can not only eliminate the big ranging errors of one radar station,but also eliminate the large ranging error of a few radars.3.The non-line-of-sight errors of the multi-static radar were studied,and the residual algorithm was improved to eliminate the false point produced by the non-line-of-sight errors.Firstly,the non-line-of-sight false points were analyzed and studied to lay the foundation of the proposed method to eliminate false points.Secondly,the residual method is improved based on the characteristic of non-line-of-sight error.Finally,the improved residual method is used to eliminate non-line-of-sight false points in the simulation.With the improved residual algorithm,the maximum error of positioning is reduced to less than 2 m.The improved residual algorithm effectively eliminates false points.4.The multi-static radars were applied to the localization of corner target and study the corner location method.Firstly,in order to adapt to the corner location in different environments,three different cases of the multi-static radars in the one-shot and multi-receive mode were studied: the transmitting radar was in the non-line-of-sight position and the receiving radars were at the line-of-sight position;The transmitting radar was at the line-of-sight position and the receiving radars were at the non-line-of-sight position;and both of the transmitting radar and receiving radars were in the non-line-of-sight position.Secondly,TDOA(Time Difference of Arrival)based on the corresponding positioning method was proposed for the three different cases.Thirdly,the experimental research was carried out on the situation that the transmitting radar was at the non-line-of-sight position and the receiving radars were in the line-of-sight position.In this case,the "mirror positioning" method was proposed in order to adapt to more complex multi-path environment.Finally,the location effect of TDOA and "mirror positioning" are compared by using measured data.Both methods can both locate the target around the corner with advantages and disadvantages.TDOA is suitable for three cases,but it is not suitable for more complex multi-path environment,and the residual algorithm for its screening effect is poor."Mirror positioning" only applies when the transmitting radar is in the non-line-of-sight position and the receiving radars are in the line-of-sight position,but it can adapt to more complex multi-path environments.And the residual algorithm is more effective.