Assessment of EGNOS System and Performance: Early Test System

J. Nieto, M.A. Molina, M.M. Romay, J. Cosmen, M.L. de Mateo, R. Román, L. Andrada

Abstract:	The EGNOS (European Geostationary Navigation Overlay Service) programme is being developed by the European Tripartite Group formed by European Union, European Space Agency and Eurocontrol with the objective to provide a Regional Augmentation Service for GPS and, potentially, GLONASS signals over ECAC, constituting the European contribution to GNSS-1. In the frame of the EGNOS programme, the Early Test System (ETS) has been developed to be a functional end-to-end EGNOS system prototype in support to the system design activities. ETS constitutes a vehicle for gaining understanding of different system level issues. It involves major EGNOS functions from the data acquisition to the user’s navigation and integrity functions, paying special attention to the different WAD (Wide Area Differential) algorithms that will be implemented in the Central Processing Facility (CPF). The main objective of the ETS is to evaluate the expected EGNOS accuracy and integrity performances, at user level, for different WAD algorithms versus mission requirements. In order to assess the validity of the system design using real data, a specific GPS/GLONASS measurement campaign was performed in the frame of the EGNOS programme. Several receivers deployed through Europe recording GPS L1/L2 and GLONASS L1 information were used as reference stations. In addition, a specific data gathering campaign was carried out in order to emulate the EGNOS user. It was based on AENA infrastructure in Salamanca where an aircraft properly equipped with GPS and GLONASS receivers was flying and recording data simultaneously to the European-wide measurement campaign. AENA infrastructure also allows very precise trajectography based on kinematic GPS by post-processing of the measurements. One of the most important parts of the WAD system are the algorithms computing clock and ephemeris corrections for the GPS and GLONASS satellites. Different algorithms were developed, integrated in the ETS and tested. Currently, the ETS is being upgraded to include specific integrity related algorithms as UDRE computation. This paper describes the ETS infrastructure, the developed algorithms, and summarises the performances obtained when the computed corrections are applied to the recorded user measurements. Different system level issues affecting the performances (e.g. effect of number and location of reference stations, system latency, message error rate, broadcast frequencies) are also presented.
Published in:	Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997) September 16 - 19, 1997 Kansas City, MO
Pages:	1345 - 1354
Cite this article:	Nieto, J., Molina, M.A., Romay, M.M., Cosmen, J., de Mateo, M.L., Román, R., Andrada, L., "Assessment of EGNOS System and Performance: Early Test System," Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997), Kansas City, MO, September 1997, pp. 1345-1354.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In