Un-difference PPP Method and Performance Assessment Based on Regional Ionospheric Model

In the field of global navigation satellite system (GNSS), the delay error caused by the ionosphere can reach several meters to several hundred meters, which is the most uncertain error source in GNSS navigation and positioning. The ionospheric delay error seriously affects the GNSS positioning effect and service performance. The real-time and accurate ionospheric model is very important for improving positioning accuracy and shortening convergence time. The high-density GNSS reference station data lays a foundation for constructing the real-time and accurate ionospheric model. In this paper, the VTEC model and the STEC model in Yunnan were realized based on the Beidou ground-based augmentation system date which is constructed and operated by Qianxun Position. The ionospheric model is added to the un-difference and un-combined PPP algorithm. The results of positioning accuracy and convergence time of the ionospheric VTEC and STEC constrained PPP models are analyzed. The results show that the convergence time of the ionospheric constrained un-difference PPP models is improved.