Precise GNSS Positioning Using Smart Devices

Area of Science:

• Geomatics Engineering
• Satellite Navigation Systems
• Mobile Device Technology

Background:

• Smart devices now offer access to Global Navigation Satellite System (GNSS) phase observations via Android.
• This enables the use of mass-market devices for precise positioning applications.
• Relative positioning techniques can leverage these observations against a base station.

Purpose of the Study:

• To evaluate the feasibility of precise positioning using smart device GNSS data.
• To determine the achievable positioning accuracy with off-the-shelf devices.
• To compare the performance of embedded smart device receivers against dedicated low-cost receivers.

Main Methods:

• Relative positioning of a Google/HTC Nexus 9 tablet using batch least-squares adjustment.
• Processing of L1 phase double-differenced observations with the open-source goGPS software.
• Testing over baselines from 10 m to 8 km, using physical and virtual base stations.
• Comparison with a co-located u-blox low-cost receiver.

Main Results:

• Decimeter-level accuracy was achieved with the Nexus 9 using rapid-static surveys without phase ambiguity resolution.
• Performance of the Nexus 9's embedded receiver and antenna was evaluated.
• Comparison data was gathered against a standard low-cost single-frequency receiver.

Conclusions:

• Smart devices with raw GNSS phase observation access can achieve decimeter-level positioning accuracy.
• Sub-centimeter accuracy is anticipated with proper integer phase ambiguity resolution, as seen in the u-blox receiver tests.
• The study validates the potential of mass-market smart devices for precise geomatic applications.