Research On Techniques Of BDS Triple-frequency Precise Point Positioning

With the rapid development of the global networking of Beidou system,the interoperability among multi-system has become the main trend of current development.Compared with other systems,all of Beidou satellite can provide triple-frequency observation data.In observation combination,the triple-frequency observation can combine with better characteristic than dualfrequency observation combination.The triple-frequency observation provides the basic conditions for triple-frequency PPP study.In this paper,the basic theory,error correction,parameter estimation method and data quality control are indepth studied about PPP technology.Then based on the above theory,the paper discusses the detection and repair of the cycle-slip in the data preprocessing,the precision analysis and application of the precise point positioning in different modes.The main work and conclusions of this paper are summarized as follows:1.Based on the theory of triple frequency combination observations and the principle of long wavelength,low ionosphere,small noise and integral combination coefficient,the combination of carrier phase and pseudorange phase are optimally selected.Then the characteristics of the two combinations are analyzed,such as the wavelength,ionospheric delay coefficient,noise and the success rate of cycle-slip detection and repair.In the optimally combined observations,selected three sets of linearly independent combination in cycle-slip detection experiment and simulation experiments,the results show that this method can detect and repair all kinds of cycle-slip.It can provide a reliable triple frequency observation data for the next step precise point positioning.2.Giving the commonly used PPP function model,and making the traditional dual-frequency ionosphere-free combination extend to triple-frequency.Then based on the combination of triple-frequency and dual-frequency ionosphere-free combination,the static precision point positioning is analyzed in many different modes.(1)In the BDS/GPS dual-frequency combination and GPS dual-frequency static PPP contrast experiment,the dual-frequency combination is better than the single system GPS in the number of available satellites and PDOP,and the convergence time and positioning accuracy are better than the single system GPS.(2)In the triple-frequency and dual-frequency static PPP contrast experiments,the dual-frequency PPP is better than triple-frequency about convergence time.But the triple-frequency PPP has better accuracy in North and East direction than dual-frequency with daily solution.(3)In triple-frequency and dual-frequency combination static PPP contrast experiments,the combination of triple frequency PPP has better results and stability than the combination of dual frequency PPP.The convergence time and standard deviation are better than the combination of dual frequency.In the three hours PPP solution,the positioning accuracy of the combined triple-frequency PPP is slightly higher than the combined dual-frequency PPP.3.It is necessary to consider the differences between the two different systems in the combined PPP.So we select the receiver clock bias as the parameter to be estimated from the inter system bias and teal-time estimate the receiver clock bias between different receiver.In the estimation of receiver clock bias experiments,the results show that the receiver clock bias is different in diverse types of receivers.But the change in the single day is relatively stable.In the multi-day single station experiments,the results show that the same type receiver’s clock bias is consistent in the short term.This work will provide some reference for the elimination of inter system bias.4.In the PPP and baseline comparison experiment,through the analysis of PPP’s hourly and daily accuracy of the solution,it is found that the precision of daily PPP can be up to the centimeter level when it is applied to the medium-long baseline,and the hourly PPP solutuion also can reach the centimeter level.So when the PPP is applied to the baseline,daily and hourly PPP solution can meet the requirements of the national control network C level,and Gamit daily solution can meet the requirements of the national control network B level.This work provides a reference for engineering application.