Analysis on Correction Accuracy of Ionospheric Model for BeiDou System

Abstract

The ionospheric error is the main error sources affecting positioning accuracy for single-frequency users. Parameters of ionospheric model are broadcast by satellite navigation systems for users, so the correction accuracy of the model has direct impact on positioning results. Based on continuous monitoring stations, Beidou system calculated and broadcast 8 parameters of Klobuchar under the geographic coordinate system, and they are updated every 2 h. In order to scientifically evaluate the correction effect of Beidou ionospheric model, firstly, the ionospheric model accuracy of different time periods and different latitudes was analyzed through the basis of GIM model provided by CODE based on Beidou latest observations. Secondly, the following positioning modes were calculated respectively. (1) Single frequency positioning without ionospheric corrections of Beidou. (2) Beidou Single-frequency + Beidou K8 model. (3) Beidou Single-frequency + GPS K8 model. The effect of residual ionospheric corrections was analyzed for positioning results. The results show that the northern hemisphere is better than the southern hemisphere for the accuracy of Beidou ionospheric model. Mid-latitudes regions can get the best correction, and the RMS of correction residuals was average about 0.6 m, and it showed a decreasing trend to the low-latitude and high-latitude regions. Beidou K8 model is better than GPS K8 model for single frequency positioning in Beijing.