Pseudo-Range Single Point and Differential Positioning Accuracy Test Based on Android Smartphone

摘要

In the era of the Internet of Everything, providing high-precision location services for the public is one of the key directions for the future development of surveying and mapping science. Under this background, Google opened the APIs of Android intelligent terminal to obtain GNSS raw data in 2016. Based on this, this paper mainly explains how to obtain the GNSS raw data of Android smartphone, and uses the Huawei P10 and Xiaomi 8 smart-phones installed with self-developed real-time positioning APP to positioning test and analysis accuracy of single-frequency pseudo-range single-point, dual-frequency pseudo-range single point and pseudo-range differential positioning. The problem of inconsistent pseudo-range and carrier phase data in the GNSS raw data of the smartphone is considered to be caused by different clocks of the smartphone; Although there is an inconsistency problem, the positioning accuracy of the smartphone can be improved by the carrier phase smoothing method; In the case of no smoothing, the differential positioning effect is limited due to excessive noise of the pseudo-range; When the carrier phase is smoothed 10-30 times, the pseudo-distance difference method can be used to improve the plane accuracy of Huawei P10 by 10-30%, the plane accuracy of Xiaomi 8 can be increased by 20-40%, and the elevation direction can be increased by 60-70%. Finally, when smoothing 30 epochs for differential positioning, the RMSE in P10 plane positioning is ±3.9 m, the elevation is ±4.3 m, the RMSE in the plane positioning of Xiaomi 8 is ± 1.1 m, and the elevation is ± 1.4 m. Although the dual-frequency de-ionospheric combination of Xiaomi 8 can effectively eliminate the influence of the ionosphere, it can't effectively improve the positioning accuracy because it can amplify the noise by 2.59 times, which needs further analysis.