Abstract: The BeiDou satellite navigation system uses the Klobuchar model to correct the ionospheric delay error for single frequency receiver users. However, due to the application of this model from the perspective of the Asian region, the correction accuracy in a specific region is even less than 50%.In order to further improve the accuracy of regional ionospheric delay correction, an improved Klobuchar model that adds five key parameters on the basis of eight correction parameters of the original model was proposed, and then the values of these additional parameters were obtained through the algorithm combining relax iterative and the golden section of the linear search.Taking Tianjin and its vicinity as an example, the measured data collected by the GPStation6 receiver was used to calculate the improved model and the original model.The global ionospheric grid data published by the International GNSS Service (IGS) was used as a reference value to compare and analyze the accuracy of the improved model and the original model.The results show that the average correction accuracy of ionospheric delay of the improved model in Tianjin and its vicinity is 10.46% higher than that of the original model, and the average accuracy reaches 77.51%.

Key words: BeiDou satellite navigation system, ionospheric delay correction, Klobuchar model, relax iterative, golden section