Description of the Message Format Analysis Conducted in the Frame of the European Egnos Project

A. Job, D. Brocard, C. Busquet, J.C. Levy, D. Flament, J.L. Jonquiere, E. Chatre

Abstract:	The capability for the GNSS signal in space to accommodate GLONASS data in addition to GPS ones has been requested by ICAO in March 96 at Nagoya (Japan). As a consequence, the previous GNSS message of RTCA which was defined for accommodating the GPS data only, had to be modified. Since the data rate available on the GNSS radio link is very limited, and since stringent message performances have to be fulfilled (low time to alarm, reduced latency for minimum error...) this new constraint to accommodate more data in the message becomes critical to manage and requires a strict optimisation of the message content and of the timings for refreshing or updating the transmitted data. From March 96, many efforts have been accomplished in order to propose solutions to this problem. The EGNOS System is being developed in Europe to provide GPS and GLONASS regional augmentation services to aviation, maritime and land users. Studies and simulations have been performed on EGNOS in order to assess the throughput capacity of the new GNSS message and to actively contribute to the definition of this message. The EGNOS Project Office has participated to international forums together with the other RSBAS service providers (WAAS, MSAS) and with the other involved international organisms like INMARSAT, RTCA and EUROCAE in order to prepare the new standard of GNSS message format. This paper provides the results and the current status of this activity.
Published in:	Proceedings of the 1997 National Technical Meeting of The Institute of Navigation January 14 - 16, 1997 Loews Santa Monica Hotel Santa Monica, CA
Pages:	165 - 172
Cite this article:	Job, A., Brocard, D., Busquet, C., Levy, J.C., Flament, D., Jonquiere, J.L., Chatre, E., "Description of the Message Format Analysis Conducted in the Frame of the European Egnos Project," Proceedings of the 1997 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1997, pp. 165-172.
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