Abstract:
Objectives It is suggested that the multi-frequency global navigation satellite system (GNSS) technology powerfully accelerate the development of high-performance location services. However, the information of multi-frequency and all-system GNSS observations is not fully used in the processing of positioning parameters. Due to that the fixed combination model used in the traditional GNSS precise point positioning (PPP) solution, the multi-frequency observations are ignored in the parameters estimation. A GNSS system-wide and frequency-wide integrated multipath error mitigation and positioning model is used to improve the PPP performances.
Methods First, a code multipath error estimation model is designed by the combination of the multi-frequency observations in the stage of observations preprocessing, where the impacts of observation noise and ionospheric error are eliminated. Second, the multi-frequency ionosphere-free combination is constructed in each system based on the GNSS observations of whole systems and all frequencies to fully model the multi-frequency observations of the users received. Third, integrated GNSS multi-system observations, the mathematical model of the whole systems and frequencies combined positioning solution is constructed.
Results According to the experiments of GNSS static and kinematics observations, it is indicated that GNSS multi-frequency observations can quickly mitigate the code multipath error, especially in the kinematics conditions, where the advantages of multi-frequency observations are significantly presented. In the kinematics positioning solutions, compared with traditional BeiDou-3 navigation satellite system dual-frequency kinematics PPP, the east, north and up directions can be improved with 81.3%, 16.7% and 79.0%, respectively, by the GNSS multi-frequency combined strategy. Moreover, the convergence time is significantly shortened.
Conclusions Therefore, it is meaningful to use the proposed multi-GNSS and multi-frequency PPP solution, which can promote the improvement of GNSS location services.