Robust airborne navigation algorithms for SRGPS

Shipboard-relative GPS (SRGPS) is an architectural variant of the joint precision approach and landing system (JPALS) that provides high accuracy and high integrity DGPS navigation for automatic shipboard landings. This research is focused on the design of robust airborne algorithms for SRGPS terminal navigation. In this context, a processing methodology is defined to optimally combine the complementary benefits of geometry-free filtering and geometric redundancy. Specifically, when the aircraft is far from the ship (inside or outside the SRGPS service volume), geometry-free filtering is used for cycle estimation of widelane integers. For dual frequency implementations, the advantage of code/carrier divergence-free filtering prior to SRGPS service volume entry can be especially significant because long filter durations can be used. In this paper, the robust navigation architecture is detailed and its performance is evaluated relative to the navigation integrity requirements for shipboard landing of aircraft.