Research And Implementation Of Pseudolite And Beidou Satellite Navigation System Combined Positioning Technique

Pseudolite applications are mainly concentrated in two aspects,they are auxiliary enhance satellite navigation positioning system and pseudolite-only to realize regional positioning.The Bei Dou second generation satellite navigation system in our country has begun trial operation in the end of 2012,it has already had the passive positioning services.As a newly-built system,BeiDou system due to its limited constellation,in some case,for example,it is high to require accuracy,and the navigation signals usually are easy to be kept out,then it will exist the situations of poor positioning accuracy and even invalid positioning.Adding pseudolite combined positioning or pseudolite-only positioning is one of the effective ways to solve the above problem.Therefore,researching on positioning technology of pseudolite participation is of great significance to improve the accuracy,validity and reliability of the Bei Dou satellite navigation system.This dissertation takes pseudolites independent positioning model and combined positioning model of pseudolites and BeiDou satellite navigation system as a starting point,firstly,the composition of pseudolite and BeiDou satellite combined system and signal structure are introduced;Secondly,the positioning equation on the basis of pseudolite independent positioning and combined positioning principle is set up,and then it is calculated by the Newton iteration method and the least square method,the algorithm is verified by MATLAB simulation software;Thirdly,according to the need of improving positioning precision,the dilution of precision which can affect the system positioning accuracy is studied,it is analyzed that the dilution of precision can be improved by pseudolite,and through observation of real-time data,the dilution of precision is calculated before and after adding pseudolite,and then the calculation results is compared and analyzed;Finally,the pseudolite and BeiDou satellite independent positioning and combined positioning algorithm is implemented and verified on FPGA and DSP development platform,the precision of positioning result is also analyzed.The studies have shown that it can position effectively under the pseudolite-only mode and combined positioning mode,it can effectively improve the geometric dilution of precision in the case of combining pseudolite with BeiDou satellite navigation system,it also can improve the positioning precision of combined system and enhance the reliability of the system.It has certain reference significance that pseudolite is successful applying to the Beidou satellitenavigation system.