|Abstract:||Traditionally, sub-meter level positioning requires the use of a geodetic RTK system or an industrial tablet/receiver equipped with professional GNSS modules and antennas. These systems are bulky, expansive and not economical for mass market adoption. Google’s initiative to provide raw GNSS measurements on smartphones with Android N in 2016 has fundamentally changed this sub-meter landscape. Now in 2019, 3 years after the initial Google announcement, we show that it is possible to achieve robust sub-meter level kinematic positioning using a smartphone with its internal PIF antennas. This is demonstrated, on an android application, under diverse conditions – not just open-sky, or assuming a static receiver as many others have done. The Xiaomi MI 8 hit the market on May 31st 2018. MI 8 was the first dual frequency GNSS smartphone, fitted with the Broadcom BCM47755 chip supporting multi-constellation (GPS, GLONASS, BEIDOU, GALILEO, and QZSS). Other brands followed, such as the Huawei Mate 20. With the release of Android P in late 2018, the power duty cycle issue encountered in earlier generation smartphone was no longer an obstacle. For the first time, consumer grade smartphone is able to provide consistent raw carrier phase measurement for multi-constellation GNSS signals. This combination of multi-constellation GNSS chipset and Android P paves the way for achieving positioning accuracy significantly better than earlier days when typical smartphone accuracy was a few meters at best. We have collected and processed smartphone data over a wide spectrum of environments, including open-sky, under canopy, half-sky building blockage, and directly under the windshield of an automobile. We analyzed the pseudorange multipath and carrier phase noise, as these are the two major limiting factors in achieving high accuracy positioning. The RMS of pseudorange, carrier phase, Doppler and the variations of the SNR are compared against the geodetic counterparts and presented. The raw measurements are processed with our in house positioning engine: xPOS, that can run on Android in real time, and uses multiple Kalman filters to optimally fuse GNSS pseudorange, carrier phase, Doppler and snr measurements. The computed position and velocities are compared against reference truth values derived from the geodetic quality RTK receivers. Finally, we present an application of our sub-meter smartphone to several real-life problems that, previously, could only be addressed with the use of industrial RTK systems.|
Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019)
September 16 - 20, 2019
Hyatt Regency Miami
|Pages:||89 - 108|
|Cite this article:||
Liu, Junjie, Xu, Zhenyu, Wang, Yingzhe, Zhao, Linc, Zhang, Ray, "Toward Achieving Robust Sub-meter Kinematic Positioning on Android with Multi-constellation GNSS," Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019), Miami, Florida, September 2019, pp. 89-108.
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