Colloquium: Sanne Lamers (Space Flight)

01 februari 2019 14:30 - Locatie: Lecture Room A - Faculty of Aerospace Engineering, Kluyverweg 1, Delft

Reduced navigation message: Optimization of the Galileo signal for fast fix applications

This research aims to decrease the time to first fix (TTFF) at the cost of position accuracy by focusing on its most dominant component: the time to read the first fix data (TTFFD). In turn, the TTFFD is decreased by reducing the size of the clock correction and ephemeris data (CED) and integrating this reduced set into the existing Galileo I/NAV message while maintaining backward compatibility. Three reduction strategiesare presented. First, the expression of the CED parameters relative to the matching almanac parameters. Second, the absorption of the clockand ephemeris time reference into related parameters. Third, the truncation of the CED parameters. The optimal parameter bit allocation perCED size is determined by means of a Monte Carlo optimisation. Finally, the optimal reduced set is integrated into the existing Galileo I/NAVmessage, since it is not only size but also the location and repetition rate of the reduced CED that determine the decrease in TTFFD.