Analysis and Testing of Data Link Time of Flight measurements in Data Fusion Algorithms for Positioning of UAV

The safe operation of Unmanned Aerial Systems (UAS) depends in most cases strongly on the availability of a GNSS (Global Navigation Satellite System) positioning solution to ensure navigation capabilities. This is essential for beyond visual line of sight (BVLOS) missions, since manual control through the visual line of sight of the pilot is not possible. Additionally, GNSS signals are vulnerable through accidental or deliberate interference. This paper proposes the use of Time-of-Flight (ToF) measurements provided by a data link as an additional, independent and operator autonomous positioning system. The characteristic low update rate (ca. 1 Hz) and low precision (ca. 30 m) of the ToF measurements are analyzed with respect to their suitability for incorporation into a sensor fusion algorithm utilizing an error-state Kalman filter. For 2-dimensional multilateration, a set of two ground based data link segments and one platform fixed data link segment are used. The ToF measurements between each of the link segments are readily available. The influence on the position solution by the coarse ToF measurement, as well as the relative position between the ground stations and the platform is analyzed.