Ground Based Augmentation Systems: A dual frequency approach

Abstract

Ground Based Augmentation System (GBAS) is the only possible satellite based radio navigation system able in a close future to achieve CAT II/III landing. The actual GBAS architecture using single frequency GPS has limitations in availability of integrity and can only achieve CAT I landings. The work I am going to present in the frame of my Diploma work details the possible strategies of dual frequency GBAS that can achieve the highest level of requirements (i.e. CAT III) for GPS as well as for Galileo navigation system. One of the highest threats for CAT II/III is the ionosphere gradient that can appear between the user and the ground GBAS subsystem during e.g. ionospheric anomaly. In order to minimize the negative influence of ionosphere gradient on the obtained results, different smoothing techniques can be used. The three smoothing techniques are presented in my work and their robustness against ionosphere anomaly is investigated. Simulations have been done with respect to different ionospheric gradient scenarios and using different combination of observables. Vertical protection levels and the availability of the integrity with respect to CAT II/III requirements is presented on the base of which the effectiveness of presented smoothing technologies is investigated. A conclusion and proposed future work ends this Diploma work.