The Ionospheric-Free Pseudorange Positioning of BDS Based on Low-Cost Dual-Frequency Receivers and its Accuracy Analysis in Southern China

This study investigates the single-point positioning(SPP) performance of a dual-frequency ionosphere-free (IF) combination based on BeiDou in southern China. A series of experiments were conducted using low-cost receivers to acquire the raw GNSS observation data from BeiDou. The positioning performance was analyzed using the dual-frequency ionosphere-free combination and pseudorange single-point positioning method at different time periods and under different motion states. The experimental results show that the IF method outperforms SPP in terms of positioning accuracy in the open environment without obstruction, especially during midday. However, the IF method amplifies the error terms, leading to larger dispersion compared to SPP. In the presence of obstructions, the IF positioning solution diverges significantly and does not perform as well as SPP. Furthermore, the experiment found that the number of dual-frequency BeiDou satellites is limited in practice. While 10 satellites are available in an open environment, this is reduced to 5–6 satellites in an obstacle environment.