The BDS augmentation positioning based smoothed pseudorange

Objectives:    Pseudo-range observations have simpler positioning mode and higher real-time performance, but the positioning accuracy is difficult to be further improved due to the influence of the noise. Carrier phase smoothing pseudorange is the main means to improve the positioning accuracy of pseudorange.    Methods:    The BDS augmentation positioning based smoothed pseudorange is proposed in the article, which uses the reference stations around the user station to generate error augmentation information to reduce user errors. At the same time, the smoothed pseudorange observations are used to generate error augmentation information. The smoothed error augmentation information does not change the error characteristics, and is compatible with the positioning of different frequency observations of the users. The users can freely choose the positioning mode according to needs.    Results:    The results show that:(1)When the single station error augmentation information is smoothed, the positioning accuracy in the N, E, and U directions is improved by 36%, 27%, and 46%, the multi station positioning accuracy is improved by 40%, 16%, 39%, the residuals after smoothing are better than those before un-smoothing, and the U direction is improved by 46% when a single station is smoothed.(2) In the user single-frequency positioning, the positioning accuracy in the N, E, and U directions after smoothing is improved by 44%, 36%, and 47%, respectively. The positioning accuracy of the three directions is increased by 18%, 21% and 60% respectively when the dual frequency is used. The three-direction positioning accuracy is improved by 16%, 31%, and 53% at three frequencies. The accuracy of the U direction is improved significantly by various schemes.(3) Compared with Hatch filtering, the method in this paper improves N, E, and U directions by 13%, 3%, and 30% respectively in dual-frequency, and 18%, 20%, and 35% in triple-frequency.    Conclusions:    The results show that smoothing method can improve the accuracy of the error augmentation information. The smoothed error augmentation information is compatible with the user's single-frequency, dual-frequency, and multi-frequency smoothed and un-smoothed positioning. The smoothing of the user's observation can also further improve the positioning accuracy.