High Accuracy Differential Positioning with Smartphone GNSS Raw Measurements

  Objectives  The demand for smartphones to provide stable high accuracy navigation and positioning service is increasing. However, limited by low-cost and low-power hardware of smartphones, there are high pseudo-range noise, serious multipath effects and frequent cycle slips, which lead to poor positioning performance.

  Methods  The paper supposes a velocity-constraint dual-frequency RTD(real time differential)/RTK(real time kinematic) automatic switching navigation model. Firstly, L5/E5a/B2 signals are more resistant to multipath effects and help to improve the positioning performance. Secondly, the multipath noise is smoothed effectively by using velocity-constraint filtering model. Finally, RTD/RTK automatic switching strategy improves the stability and accuracy of positioning, especially under urban environment where continuous carrier phase measurements are insufficient.

  Results and Conclusions  This paper assesses the positioning performance of the Huawei Mate40 and the results show that the fixed rates of static positioning and pedestrian positioning are 99.67% and 57.99% respectively. Horizontal positioning accuracy of the pedestrian test is about 0.5 m. The vehicle positioning results show that more than 70% epochs can reach lane-level accuracy, which shows that the method supposed in this paper can basically meet the smartphone users' needs of high accuracy navigation and positioning service under urban environment.