Abstract
The recent access to GNSS (Global Navigation Satellite System) phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether this is feasible, and which positioning accuracy can be achieved by relative positioning of the smart device with respect to a base station. Positioning of a Google/HTC Nexus 9 tablet was performed by means of batch least-squares adjustment of L1 phase double-differenced observations, using the open source goGPS software, over baselines ranging from approximately 10 m to 8 km, with respect to both physical (geodetic or low-cost) and virtual base stations. The same positioning procedure was applied also to a co-located u-blox low-cost receiver, to compare the performance between the receiver and antenna embedded in the Nexus 9 and a standard low-cost single-frequency receiver with external patch antenna. The results demonstrate that with a smart device providing raw GNSS phase observations, like the Nexus 9, it is possible to reach decimeter-level accuracy through rapid-static surveys, without phase ambiguity resolution. It is expected that sub-centimeter accuracy could be achieved, as demonstrated for the u-blox case, if integer phase ambiguities were correctly resolved.
Highlights
The use of single-frequency GNSS (Global Navigation Satellite System) receivers and antennas for high-precision static applications, such as geodetic monitoring, is becoming more and more important due to the extremely low cost of single-frequency hardware, originally designed and produced for the mass-market, and to the increasing number of GNSS systems available
In this work we present results of experiments performed to study the positioning accuracy achievable by means of the GNSS receiver and antenna integrated into a Nexus 9 tablet, aiming to prove the possibility to perform accurate rapid-static positioning with smart devices, without external components at the user’s location
Since the aim of the present work is mainly to evaluate the accuracy level that can be reached by means of rapid-static surveys with smart devices, the 1.5-h solutions with the different base stations were computed to be used as reference to evaluate the 15-min session results for both the Nexus 9 and the u-blox receivers
Summary
The use of single-frequency GNSS (Global Navigation Satellite System) receivers and antennas for high-precision static applications, such as geodetic monitoring, is becoming more and more important due to the extremely low cost of single-frequency hardware, originally designed and produced for the mass-market, and to the increasing number of GNSS systems available. Such applications require, in order to reach millimeter-level accuracy, the deployment of stationary GNSS units, delivering raw observations, and the processing of sufficiently short baselines [1,2,3,4,5,6,7]. Several studies were performed [12,13], but they were all limited in the positioning accuracy by the Sensors 2017, 17, 2434; doi:10.3390/s17102434 www.mdpi.com/journal/sensors
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