A virtual receiver concept and its application to curved aircraft-landing procedures and advanced LEO positioning

Abstract

Kinematic positioning of highly dynamic platforms by a global navigation satellite system (GNSS) often suffers from fast-changing satellite visibility and signal obstruction. This is especially true for curved landing approaches of aircrafts or low earth orbit (LEO) satellites. In order to improve this situation, we present a mathematical concept that combines GNSS observations of multiple optimally installed antenna–receiver pairs mounted on a single rigid platform into one enhanced positioning solution. We call this concept “Virtual Receiver” as the position of the final solution can be chosen arbitrarily on the rigid platform. The location and orientation of the antennas are selected in such a way that their combined antenna field of view is enlarged with respect to each single, contributing antenna, thus improving the navigation performance. It will be shown that the concept can be applied for code-only navigation as well as for static and kinematic positioning with PPP. Using real data of a highly dynamic flight experiment, the performance of the virtual receiver positioning solution is compared against a single antenna positioning solution. We found that the satellite availability and the precision of the virtual receiver positioning solution significantly outperform the positioning solution of a co-located single antenna. The 95% error bound is reduced by up to 25%. The integrity is assessed by means of the internal reliability and the Stanford diagram, where a better or equally good integrity monitoring availability is found for the virtual receiver with respect to the single antenna. In particular, the vertical receiver autonomous integrity monitoring (RAIM) availability percentage is remarkably high, being 89.4% for this highly dynamic flight. This methodology for single-frequency code-based positioning is extended to precise point positioning (PPP) and applied for a static experiment and LEO precise orbit determination. Thus, the virtual receiver concept is an interesting possibility to improve the navigation performance parameters.