Multipath Error Repression Based On Pseudorange Model

Global navigation satellite system(GNSS)has been widely used in various fields and become an indispensable part of people's life due to its features of all-weather,high precision and automation.However,in some complex environments(such as dense cities,valleys,etc.),multi-path interference is difficult to be eliminated by general difference technology due to its spatial uncertainty and temporal irrelevance,and thus becomes one of the main error sources to reduce the positioning accuracy.At this time,it is particularly important to study the multipath error suppression technology to meet the needs of high precision.This paper mainly takes global positioning system(GPS)as an example,and uses the method based on pseudorange model to conduct multipath suppression technology research in the positioning and navigation operation stage of the software receiver.The main research work is as follows:1.This paper describes the research problem based on the pseudorange model and adopts a two-step positioning method to suppress multi-path errors,and finally completes the positioning of the software receiver.In the first step,the traditional positioning method is used to locate a rough user location without considering multipath interference.In the second step,the positioning problem is transformed into an optimization problem to be solved by using the optimization algorithm to suppress the multipath error after the multipath interference is introduced to pseudorange model.2.A multipath error suppression method based on teaching optimization(TLBO)algorithm is proposed.Aiming at the problem of the residual phase in the traditional positioning method in the first step,the residual carrier phase and the residual pseudo-code phase are combined to eliminate the residual phase.For the second step,TLBO algorithm is used to solve the optimization problem and the multipath error suppression is completed.3.A multipath error suppression method based on modified TLBO algorithm is proposed.Aiming at the shortcomings of traditional TLBO algorithm,such as slow search speed and easy to fall into local optimum,a modified TLBO algorithm was proposed by introducing the idea of adaptive teaching factors,cross strategies and adaptively population size,which was applied to the multipath error suppression.4.Finally,the GNSS intermediate frequency signal collector produced by Shanghai Yuzhi company was used to collect actual satellite data at Mingxiang Campus of Taiyuan University of Technology to carry out experiments in order to verify the effectiveness of the multipath error suppression method proposed in this paper.The results show that the proposed method has better positioning results compared with the multipath error suppression method based on particle swarm optimization(PSO)algorithm,differential evolution(DE)algorithm and variable projection(VP)method.