GNSS/GPS Robustness for UAS

Abstract: UAS (Unmanned Aircraft Systems) are found today in many different environments performing different tasks, which puts different demands on the GNSS (Global Navigation Satellite System) engine. In this thesis three experiments are performed that are related to UAS GNSS. One experiment aims to discover if the onboard electronics cause harmful RFI (Radio Frequency Interference) to the GNSS engine, due to close proximity of various electronic components and the GNSS antenna. The other two experiments evaluate the performance of high accuracy RTK (Real Time Kinematic) and its applicability to UAS, one static experiment and one dynamic experiment. Some comparisons to manned aviation are also made, together with some background and theory to GNSS and RTK. The results show that RFI is present during one of the measurements, and is likely caused by the onboard electronics. The RFI causes a large drop in the carrier-to-noise ratio, which could negatively impact accuracy. Results from RTK experiments show some indication that RTK could successfully be implemented on UAS for navigational purposes. Future work should be focused on performing a combination of the RFI and RTK experiments during a UAS flight, with focus on how RFI impacts RTK measurements.