Construction Of Simple And Convenient BDS Positioning Reference And Real-time Positioning Application

At present,the Global satellite navigation system(GNSS),represented by Chinese Bei Dou Navigation Satellite System,has been more and more widely used in the field of civil highprecision Positioning,Navigation and Timing(PNT)services.However,in the areas of military anti-terrorism,long range strike,ocean and remote region,it is difficult to obtain the highprecise coordinates because of the controlled and limited communication conditions,the lack of reference stations and self-built frame network.In this case,the real-time positioning service with high precise cannot be provided by GNSS.Based on the above problems,the molds of global absolute positioning and region relative positioning were proposed in this paper,which has the higher security.The main contents are as follows:(1)the global absolute position with decimeters to centimeters levels can be estimated by using the single-station observations including the broadcast ephemeris and observation data stream.It is based on the construction of simple and low-cost receivers of Beidou in the conditions without communication.(2)According to the global absolute positioning,the real-time relative positioning algorithm with uniaxial enhancement were study in this study,which can realize the positioning with decimeters to centimeters levels.(3)The rapid switching algorithm for reference stations has been studied in this research.The reference station can be switched to other station rapidly when the original reference station is destroyed.The switching error is on centimeter level.(4)Finally,the services of global absolute positioning on centimeter level and real-time dynamic PPP were studied in this paper.It relied on the correction information of SSR global enhancement.The research content and innovation of this paper are as follows:(1)A method of absolute position datums determination based on the BDS broadcast ephemeris is built.The Kepler orbit and clock offset parameters are obtained from broadcast ephemeris file and the pseudo-range and carrier phase observation are used,then,the static sequential least squares algorithm is used for single station multi-day observation and navigation file,the positioning accuracy and convergence speed is studied,so that the simple and convenient absolute positioning datums can be provided for this region.The numerical simulation result shows that: in static mode,the positioning accuracy of one-day solution of broadcast ephemeris is 30.00 and 20.00 cm in horizontal and vertical,respectively.If the observation time is prolonged to seven days,the mean positioning accuracy of horizontal and vertical can achieve 9.5 and 14.3 cm,respectively.(2)A simple seamless and fast switching technical idea of datums station is proposed.A kind of absolute datums hardware device of scatter is developed,and a one-way augmentation real-time differential positioning algorithm based on reference station correction is constructed,and the regional centimeter-level relative positioning services is achieved.The numerical simulation result shows that: when the datums station is destroyed or interrupted.The impact of datums station switching strategy on the kinematic positioning accuracy of rover station is only centimeter-level.When the impact of coordination difference of datums stations and distance is not considered,only the ambiguity is reinitialized,resulting the horizontal and vertical positioning errors are 3.4 and 10 mm,respectively.This algorithm can provide decimeter-level absolute positioning accuracy and centimeter-level relative positioning accuracy in a self-close area only under the support of broadcast ephemeris.(3)Based on the SSR global augmentation correction information,the technical process of constructing centimeter-level global absolute datums and real-time kinematic PPP is designed.The technical method of SSR global augmentation real-time stream products solution is studied.The performance level of real-time augmentation Precise Point Positioning(PPP)services is calculated and demonstrated.The numerical simulation result shows that: when the observation time is one hour,the BDS static PPP can provide an absolute positioning datums with the accuracy is better than 10 cm.Compared to BDS-only positioning,the BDS/GPS combination positioning can improve the convergence speed and accuracy by one-time and 39.6%,respectively.The positioning accuracy provided by the BDS kinematic PPP is better than 20 cm.Compared to BDS-only positioning,the BDS/GPS combination positioning accuracy can be increased by 35%.