Dilution of precision factor in Galileo and GPS MEOSAR constellations for European coverage

The current paper investigates Search and Rescue (SAR) distress beacon location accuracy figure for Cospas-Sarsat (C/S) MEOSAR systems, specifically for its planned Galileo and GPS components. Dilution of precision (DOP) closed form formulations are provided for the geolocation techniques using time-difference-of-arrival (TDoA), frequency-difference-of-arrival (FDoA) and their combination. Moreover, the impact of the Galileo and GPS MEOSAR satellite constellation characteristics, and of the Galileo / SAR Local User Terminals (MLT) locations on the distress beacon accuracy figure is analyzed for beacons within the European SAR coverage area (ECA). More in detail, three arbitrary Galileo MEOLUTs in the Canary Islands (Maspalomas), in the Norvegian Sea (Jan Mayen) and in southern continental Europe (Toulouse), and a single emitting beacon located in the ECA have been considered; the simulation time was ten days for Galileo and one day for GPS, corresponding to respective track repetition times. The study is conducted using a dedicated Matlab developed software tool. Analysis of the results are provided and compared for Galileo-only and GPS-only cases, conclusions are drawn.