Improved Hybrid Navigation for Space Transportation

Abstract

This paper presents a tightly coupled hybrid navigation system for space transportation applications. The tightly integrated set-up, selected for its robustness and design flexibility, is here updated with GPS Pseudoranges and Time-Differenced GPS Carrier Phases (TDCP) to promote fast-dynamics estimation. The receiver clock errors affecting both GNSS observables are analysed and modelled. Tropospheric delay-rate is found to cause major disturbance to the TDCP during atmospheric ascent. A robust correction scheme for this effect is devised. Performance is evaluated using real GPS measurements.