Research On GNSS Stereoscopic Grid RTK Service And Smartphone Positioning Algorithm

National and provincial GNSS reference station networks have been built,becoming an important infrastructure for geographic information space.The NRTK technology based on Virtual Reference Station(VRS)has been widely used.As a relatively common positioning method in various provinces,VRS technology has a 1:1customized service model between users and virtual reference stations,which has the problem of not being able to scale users.At the same time,the atmospheric delay error in the environment of large height difference between the base station and the rover causes the error of the VRS observation value to be too large,which affects the user’s RTK positioning accuracy.Aiming at the above problems,this paper proposes a GNSS stereoscopic grid RTK service method considering terrain information.The new generation of mobile phones is equipped with GNSS positioning chips,which can obtain original observations through the Android open interface,making it possible to study mobile phone navigation and positioning algorithms.The positioning accuracy of mobile phones cannot meet the needs of users in daily life.To meet the urgent needs of high-precision navigation and positioning,this paper proposes a Smooth RTK dynamic positioning algorithm for Android mobile phones.This paper focuses on the related research on service algorithm and mobile phone terminal algorithm.The main research results are as follows:(1)The basic principle of GNSS NRTK positioning is introduced.Including:station-to-satellite double-difference observation equation and linearization,multi-frequency observation value linear combination method,cycle slip detection and repair method,observation value error term and processing ideas.(2)Aiming at the server-side algorithm,this paper proposes a GNSS stereoscopic grid RTK service method.The traditional VRS service model is improved,and the N:1popular enhanced location service model is adopted.The division basis,generation method and error characteristics of the stereoscopic grid are studied.On the premise of not losing the user positioning accuracy,the optimal stereoscopic grid resolution is determined to be 4′×4′,which can effectively solve the problem that traditional VRS cannot scale users problem,provide users with real-time centimeter-level enhanced positioning services.(3)Aiming at the elevation difference between the virtual reference station and the reference station of stereoscopic grid points,a stereoscopic linear interpolation algorithm considering the elevation direction is proposed,and the ionospheric and tropospheric residuals are small after interpolation.Aiming at the elevation difference between the virtual base station and the rover of the stereoscopic grid points,the stereoscopic grid modeling algorithm is used to optimize.The combination of the two algorithms can effectively solve the problem of reduced RTK positioning accuracy caused by the difference in elevation between the base station and the rover.(4)Aiming at the positioning requirements of mobile phone terminals,this paper proposes a Smooth RTK dynamic positioning algorithm for Android mobile phones.The quality of the original observations of MI 8 and HUAWEI P40 mobile phones is analyzed,the data preprocessing strategy is given,and the random model and GNSS function model that conform to the characteristics of mobile phone observations are used.Compared with the unprocessed RTK solution,the simulated dynamic experiment shows that the Smooth RTK plane positioning accuracy of the MI 8 terminal is real-time decimeter level,and the elevation positioning accuracy is within the meter level;the HUAWEI P40 terminal,the Smooth RTK plane positioning accuracy is real-time sub-meter level,and the elevation positioning accuracy is slightly lower.Difference.The dynamic experiment of the trolley shows that the Smooth RTK plane positioning accuracy of the MI 8 terminal is at the real-time decimeter level;the Smooth RTK plane positioning accuracy of the HUAWEI P40 terminal is real-time sub-meter level,and the trajectory has an overall deviation phenomenon.Vehicle dynamic experiments show that the MI 8 terminal can provide users with real-time decimeter-level navigation and positioning services;the HUAWEI P40 terminal has a Smooth trajectory without gross positioning errors,but there is an overall deviation between the trajectory and the receiver reference trajectory.Simulation and dynamic experiments verify the reliability and superiority of the Smooth RTK algorithm,which can significantly improve the dynamic positioning accuracy of mobile phones.(5)Developed server TGRTK software and terminal CASM-RTK positioning software.The mobile phone stereoscopic grid RTK experiment shows that: MI 8 and HUAWEI P40 terminal GPS+BDS fusion system Smooth RTK can realize real-time decimeter-level positioning,which meets the needs of large-scale mobile phone users and navigation and positioning.There are 94 figures,27 tables and 61 references.