Orbit ephemeris monitors for category I LAAS

Abstract

This paper describes sufficient methodologies to monitor GPS satellite orbit ephemeris for Category I aircraft precision approach navigation. In the absence of a satellite maneuver, it is shown that a monitor based on the projection of previously validated ephemeris parameters is adequate to meet navigation integrity and availability requirements. After scheduled stationkeeping maneuvers, no previously validated ephemerides are available, so a measurement-based method is required. The feasibility of such a monitor is also established.