A technique for precise positioning of High Altitude Platforms System (HAPS) using a GPS ground reference network

Abstract

GPS can play an important role in the positioning of High Altitude Platforms Systems (HAPS). In such GPS applications the residual tropospheric delay in GPS measurements is a major error source. Contrary to the case of static GPS applications, it is difficult to estimate the tropospheric delay simultaneously with the ambiguities and coordinates in kinematic mode. In this paper four techniques to mitigate the tropospheric delay error are compared. Preliminary tests using an aircraft has shown that the global tropospheric model may not be adequate for precise positioning. Both the method using a numerical weather model and the method using surface meteorological measurements significantly improved the performance of ambiguity resolution on-the-fly. However, the method using meteorological data obtained by the aircraft and the zenith tropospheric delay, estimated from a ground GPS network, has shown the best performance.