Network Rtk Reference Station Solution And Atmospheric Delay Modeling Based On Non-Combined Observation Model

With the construction and modernization of global navigation satellite system,satellite navigation and positioning technology plays an important role in human daily production and life.Net-RTK technology with its high precision,high reliability,wide range of services and many other features to a wide range of special promotion and application.In this paper,two aspects of network RTK base station solution and atmospheric delay error modeling are studied.The calculation model of the base station,the parameter estimation method,the characteristics of the main error source and the processing strategy are analyzed in detail.Based on the double-difference non-combinatorial model,the problem of ambiguity resolution of the base station is used to accelerate the convergence of ambiguity by using the method of atmospheric delay prior information constraint.Based on the virtual base station technology,the atmospheric delay error modeling method is analyzed and studied systematically.The models based on linear interpolation and linear fitting are analyzed and compared,and their characteristics and applicability are summarized.The influence of the tropospheric delay error on the elevation difference between stations is analyzed.In the area with large undulating terrain,the accuracy of the tropospheric delay error correction term after normal modeling is low,which leads to the model value after modeling Value difference between the larger,the use of the direction of the deviation correction method to carry out the refinement of the model.In addition,as one of the service contents of network RTK,this paper analyzes and compares the different modes of sub-level positioning algorithm.The main contents of this work can be summarized as follows:(1)Describes the basic theory in the process of network RTK solution,including the stochastic model of the baseline solution function model,the observed value and parameters,the mathematical method of parameter estimation,and the error source and the processing strategy of the main error term.(2)The preprocessing of the base station data,the theoretical method of derivation and verification of the commonly used dual-frequency detection cycle slip is carried out.In order to speed up the convergence of the ambiguity,the tropospheric constraint method and the ionospheric constraint method Effect.The experimental results show that the constraint of atmospheric delay can effectively improve the accuracy of ambiguity floating point solution and speed up the initialization of the baseline.(3)The difference of the atmospheric difference between the base stations is analyzed.On the basis of this,the various error modeling methods are described theoretically and the measured data are used to verify the effect of different models.The results show that the model effect of the deviation correction is taken into account,and the error correction term is obtained by combining the common plane interpolation method with the elevation deviation correction.Preferably,the accuracy of the model is better than 3 cm when the user station and the base station elevation difference reaches 1098 m.(4)The theoretical analysis and comparison of the sub-scale pseudo-range differential positioning algorithm for different models are carried out.The main results are analyzed from the mathematical model,the commonly used broadcast standard and the algorithm performance,and the suggestions are given.