Towards centimeter accurate positioning with smartphones

Nowadays, Android enables the access of GNSS raw data and, thus, an in-depth evaluation of smartphone GNSS observations. We analysed and compared GNSS code and phase observations and the achievable position accuracies of three Android devices: tablet Google Nexus 9, smartphones Xiaomi Mi8 and Huawei P30. Not all the phase observables of these devices possess the property of integer ambiguities. We were able to perform precise antenna calibrations on GPS L1 for both smartphones and obtained corrections for the phase center offsets and phase center variations. The latter do not exceed 1 to 2 cm. With successful ambiguity fixing, we achieved standard deviations of the 3D positions of 2 to 3 cm after 30 minutes of static observations in baseline mode.