In this master thesis, we pursued the idea of building a low-cost GNSS system and upgrading older Phantom 4 Pro aircraft for direct georeferencing purposes. In the thesis, a low-cost GNSS receiver ZED-F9 was tested both on the ground and on the aircraft. The receiver was tested using the real-time kinematic (RTK) and in post-processing kinematic (PPK) method. In the ground tests, the reference coordinates of the staked out points were compared first with the coordinates obtained using the low-cost GNSS receiver. To determine the flight trajectory position accuracy, a 360° mini prism was attached to the aircraft, which was measured using the classical terrestrial method. The accuracy of the determined coordinates, on the ground and on the aircraft, was less than 2 cm for both kinematic methods (RTK and PPK). In all four experiments, the position accuracy for the PPK and RTK methods was below 3 cm for horizontal components and less than 6 cm for the altitude. The results of the built low-cost GNSS system show that unmanned aerial vehicles can be quite well upgraded with sensors for positioning and monitoring aircraft rotations. In the future, it will be necessary to resolve the issue of time synchronisation of photographs and other sensors on the aircraft.