PEGASUS - Prototype Development for EGNOS Data Evaluation - First User Experiences with the EGNOS System Test-Bed

EGNOS is the European component of a satellite-based augmentation to GPS and GLONASS and is being developed under the responsibility of a Tripartite Group of the European Space Agency (ESA), the Commission of the European Union and the European Organisation for the Safety of Air Navigation (EUROCONTROL). EUROCONTROL is coordinating and taking an active role in operational validation activities that will need to demonstrate that the use of GNSS-1, including EGNOS, meets the mission requirements from Civil Aviation. In February 2000, the European Satellite Test Bed (ESTB), a prototype of EGNOS, became operational. The ESTB broadcasts ranging information, pseudorange corrections and integrity information for GPS. As part of an early trials activity EUROCONTROL initiated a project called PEGASUS (Prototype EGNOS Analysis System Using SAPPHIRE) with the objective to gain experience in using the ESTB in preparation for the operational validation of EGNOS itself. PEGASUS is a tool to be used for the evaluation of ESTB observed and corrected GPS data. It allows for the processing of ranging, wide-area differential and integrity information for GPS and ESTB data. A generic data format (made available in an interface control document ICD) has been produced in order to encourage the standardisation of data acquisition and storage in Europe. This paper will describe the background of the PEGASUS tool, explain its features and will present first experiences gained with the ESTB during its development. Results from measurements and data analysis of the ESTB will be presented. Particular attention will be paid to the achieved system performance and how far the ESTB is already able to fulfil civil aviation mission requirements.