Ground multipath mitigation with UAVs

11 August 2021

The team at the Institute for Space Technology and Space Applications (ISTA) has been researching the positioning performance of modern smartphones for years. In numerous experiments it could be shown that for the fixing of the phase ambiguities in RTK, the limiting factor are cycle slips and, above all, (ground) multipath. With fixed ambiguities a position accuracy in centimeter range is possible. Such high levels of accuracy are particularly necessary for AR / VR or safety-critical applications.

To eliminate the (ground) multipath and to show that even without signal amplification or choke ring antennas, ambiguity fixing is possible with modern smartphones with dual-frequency GNSS receivers, an in-house UAV was used to get the smartphones high into the sky.

The UAV flew in 10-meter steps up to a height of 80 m and was tracked by a total station to track the position of the UAV for post-processing. The data on the smartphones was logged by our own IMU/GNSS logger (available in the Google Play Store: https://play.google.com/store/apps/details?id=com.ista.android.apps.location.gps.gnsslogger). The first results show that the (ground) multipath can be largely eliminated and high fixing rates can be achieved.