Study On Positioning And Timing Method Based On VLBI Mode

Positioning,Navigation and Timing(PNT)technology is a key technology to describe time and space.Human beings are increasingly dependent on PNT with the times progress and the development of technology.The key role of satellite navigation system is to provide the time and space reference and all kinds of relevant PNT information.However,when the navigation satellite is unable to provide services due to fault,strike and interference or the users are difficult to accept the navigation signals,the users who only use satellite navigation system to provide positioning,timing and other services may face the problem of not being able to obtain the time,location and other information.Therefore,it is particularly important to develop the navigation and positioning methods that utilize multiple signal sources,multi-technology integration and satisfy the needs of multidomain application.Based on above purposes,a method of positioning and timing that using Very Long Baseline Interferometry(VLBI)technology is presented in this thesis.The principle and method of using VLBI technology for positioning and timing is introduced concretely,and verifies the possibility of this method by calculating the differential simulation data between stations generated from the observation data of the Satellite Orbit via Transfer Tracking System and the VLBI actual observed data.The main contents include the following:(1)Firstly,the principle and method of using VLBI technology for positioning and timing is introduced in detail,a mathematical model about positioning and timing by VLBI technology is established.When using only GEO satellite as navigation satellites,add the earth ellipsoidal constraint equation to constrain the elevation.At the same time,considering the case of observational equation is ill-conditioned equation,the weighted iterative improvement method is used to improve the condition number of the illconditioned observation equation and improve the accuracy of the equation solution;(2)The principle and method of generating the inter-station differential observation data from the observation data of the mode of receiving the own-stationdissemination signals and the mode of receiving not only own-station-dissemination but also other-station-dissemination signals of the Satellite Orbit via Transfer System are studied.The similarities and differences between the differential data and the VLBI observation data are compared.The simulation data are calculated and the positioning accuracy of the user in N direction is about 10 m,the positioning accuracy in the E direction is about 1.2m,the timing accuracy is about 14 nanosecond,this results are analyzed and explained.At the same time,considering that the VLBI2010 system of the National Time Service Center,Chinese Academy of Sciences has only the status of single satellite observation data,the difference observation data between stations is used to simulate this situation,and the possibility of positioning and timing under this condition of only single satellite observation data is analyzed.Then,several factors that affect the accuracy of positioning and timing are analyzed.(3)Finally,the actual observational data of the VLBI2010 system of the National Time Service Center,Chinese Academy of Sciences is applied.In the case of only single satellite observation data,it is assumed that the clock difference between the base station and the users and the coordinate component of the users in a certain direction are known,then calculate the coordinate component of the users in other directions.When the clock difference between JinLin and SanYa station and the X coordinate are known,the error of SanYa station in N direction is about 0.48 m,the error in E direction is about 0.05 m.Compare this results with the computation by using the inter-station differential observation data.Moreover,a method is proposed for calculating the correction of station coordinate by using the residual value of VLBI own observation data when observe the radio source.