Centimeter accurate GNSS positioning with smartphones
The Android operating system was extended to provide GNSS raw observations some years ago. This facilitated the analysis of smartphone GNSS observations and development of adapted positioning algorithms. Nowadays, a couple of GNSS chips inside smartphones not only observe GNSS code pseudoranges but also continuous GNSS carrier phases, which possess the property of integer ambiguities.
We have tested some of those smartphones in-depth, especially a Huawei P30 that works with dual-frequency GNSS-Chip Kirin 980. Ambiguity fixing was performed successfully on the first GPS frequency which enabled centimeter level positioning in baselines to geodetic reference receivers.
We determined the phase center and phase center variations of Huawei P30 smartphone in a field calibration procedure. Using this smartphone in an upright orientation, the L1 phase center is located slightly to the right of the central axis and a bit below the upper edge of the device. Systematic phase center variations turn out to be fairly small, especially when comparing with the effects of multipath onto the carrier phase observations.
The obtained accuracies of the coordinate results are much worse as compared to those achievable with geodetic equipment, but still, in a favorable environment centimeter level positioning results can be obtained after just a few minutes of static observations. Few centimeter level accuracies can also be achieved in kinematic mode if carrier-phase ambiguity fixing is successful.
Publications
Wanninger, L., Heßelbarth, A. (2020): GNSS code and carrier phase observations of a Huawei P30 smartphone: quality assessment and centimeter‑accurate positioning. GPS Solutions, 24:64. DOI: 10.1007/s10291-020-00978-z
Heßelbarth, A., Wanninger, L. (2020): Towards centimeter accurate positioning with smartphones. European Navigation Conference (ENC). November 2020. IEEE Explore
Heßelbarth, A., Wanninger, L. (2021): GNSS-Messungen mit Smartphones - Analyse der Beobachtung und cm-genaue Positionsbestimmung. Zeitschrift für Geodäsie, Geoinformation und Landmangement, Heft 3/2021, 146:189-197. DOI: 10.12902/zfv-0355-2021