ABSTRACT
In order to validate the navigation message being broadcast by the satellites, an independent estimation of the Signal-In-Space Error (SISE) is performed in real-time. This estimation, which is also modeled as a random process with an associated uncertainty, allows the verification of the overbounding of the true SISE distribution by the broadcast SISA. The assumption made in this case is that the difference between the true SISE projected at Worst User Location (WUL) and the estimated one can be overbounded by a Gaussian distribution with the standard deviation equal to SISMA. In this context, the SISMA can be considered as a quality measure of the integrity check within the IPF. Additional information on the Galileo integrity concept can be found in (Oehler, 2005). From the operational point of view, the IPF design does not consider any real-time human intervention, so key factors are the algorithms’ robustness and reliability, directly derived from the stringent integrity and continuity requirements.
