Quality analysis of multi-GNSS raw observations and a velocity-aided positioning approach based on smartphones

• Published in: Advances in space research 2019-04, Vol.63 (8), p.2358-2377
• Main Authors: Liu, Wanke, Shi, Xiang, Zhu, Feng, Tao, Xianlu, Wang, Fuhong
• Format: Article
• Language: English
• Subjects: Android smartphone; Duty cycle; GNSS raw observation; Quality assessment; Static and kinematic positioning
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2019.01.004

The Global Navigation Satellite System (GNSS) chipset is now embedded in almost all Android smartphones, and the market demand for location services and navigation based on this chipset has increased. In May 2016, Google announced that the developers could access some Android GNSS raw measurements, including the pseudorange, carrier phase measurements and navigation massages in Android 7.0. This access has led to the development of advanced algorithms and the introduction of external corrections and multi-source information to improve the accuracy and reliability of the solution. In this paper, a comprehensive and in-depth analysis of the quality of raw GNSS observations of Android smartphones is conducted in terms of the carrier-to-noise density ratio (C/N0), the GPS/GLONASS/BDS multi-system pseudorange noise, the tracking capability of the carrier phase, and velocity estimation. More importantly, the impact of the duty cycle mechanism is analyzed in detail using a low-power consumption strategy on the GNSS observations for the first time. Moreover, a modified pedestrian positioning algorithm is proposed based on the quality of the Android GNSS observations. The kinematic results show that the RMS value is less than 3 m in the horizontal direction and approximately 5 m in the vertical direction, which is more precise than the Android solution. In addition, the solution is more continuous, smoother and more reliable and could meet the navigational demand of most mass users.