Galileo Ephemeris Consolidation and Control Analysis – GECCO

Cedric Rouch, Bernard Bonhoure, Norbert Suard, Mikael Mabilleau, Jonathan Vuillaume, Christelle Dulery, Didier Lapeyre, Celine Sauce

Abstract:	Broadcast GNSS ephemeris potentially represents a significant error budget for the final user of satellite navigation systems. CNES, the french space agency, has initiated a project awarded to Thales Service and Egis Avia with the overall objective to assess operational management and quality of GALILEO ephemeris. GALILEO ephemeris performance evaluation requires the building of consolidated ephemeris files. GECCO (GALILEO Ephemeris Consolidation and Control) software was developed by Thales Service to provide, for a given period of time, such global ephemeris files in Receiver Independent Exchange format (RINEX) for the GALILEO free access service signals (I/NAV [E1-B, E5b-I], F/NAV [E5a-I]). These consolidated files are built using the open, trustable, global network of the International GNSS Service Multi-GNSS Experiment (IGS MGEX) initiative. The control and consolidation process of GECCO software and the wide variety of receivers used ensure the building of global ephemeris files reflecting the navigation data broadcast by the GALILEO constellation over the entire surface of the world. A tool, GECCO-Analysis, was developed by Egis Avia to analyze the global RINEX files generated by GECCO software and to provide key elements of GALILEO ephemeris performances and management. After a presentation of GECCO and the methodology used, GALILEO ephemeris analysis results are given for the period from September 2013 to May 2014. As GALILEO is currently under deployment, those results shall be consolidated with time. It shall not be analyzed as potential state of the final GALILEO performance. The study shows for the four IOV satellites typical 10 minutes renewal ephemeris rates, orbits and clocks performances at the reception time better than 6.5 meters at 95%. Other indicators are provided regarding the broadcast GALILEO System Time (GST) to UTC and GPS Time to GST conversion. Some information is also provided on health and validity flags management.
Published in:	Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015) September 14 - 18, 2015 Tampa Convention Center Tampa, Florida
Pages:	1947 - 1957
Cite this article:	Rouch, Cedric, Bonhoure, Bernard, Suard, Norbert, Mabilleau, Mikael, Vuillaume, Jonathan, Dulery, Christelle, Lapeyre, Didier, Sauce, Celine, "Galileo Ephemeris Consolidation and Control Analysis – GECCO," Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015), Tampa, Florida, September 2015, pp. 1947-1957.
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