GIOVE-B Navigation Message Performance Analysis and Signal in Space User Ranging Error (SISRE) Characterization

G. Galluzzo, M. Sánchez-Gestido, F. Gonzalez, S. Binda, G. Radice, A. Hedqvist, R. Swinden

Abstract:	Since the launch of GIOVE-B in April 2008, the GIOVE Mission Segment (GIOVE-M) has been significantly enhanced through an upgraded core infrastructure, in pursuing its important role as risk mitigation asset in the frame of the Galileo project. The GIOVE mission, with two experimental satellites, GIOVE-A and GIOVE-B and with the GIOVE Processing Centre (GPC) including its worldwide network, recently extended to 15 Galileo Experimental Sensor Stations (GESS), is about to achieve its maturity, paving the way for the first In Orbit Validation (IOV) Galileo activities. In this scenario, with the ground mission operations reaching their full capabilities and with consolidated experimentation activities on the on board technology of the critical satellite, the attention is being shifted towards the overall system navigation performance. The primary function of the GIOVE Processing Centre is to generate the navigation message data, comprising satellite ephemerides and clock corrections. In addition, it is required to continuously monitor the orbit determination and time synchronization processing performance along with the continuity and the quality of the data collected from the GESS network. In this context, a set of Key Performance Indicators (KPIs) provide an essential assessment and monitoring of the system performances at user level. Generated by a software tool developed and running on a dedicated GPC facility, the KPIs cover the areas of the Navigation Message performance including the determination and prediction accuracy of satellite orbit and clock, navigation message latency and Signal In Space User Ranging Error (SISRE). The navigation message latency, for a given navigation message, is simply defined as the latency period since the GPC generated the clock/ephemeris prediction used to create the particular message data upload. This latency includes different delays, starting from the time required to collect the observables from the stations and to generate the clock/ephemeris prediction, plus the additional delay in its transmission. Therefore, it is an important indicator for the validation of the end-to-end navigation message chain, from its generation by the E-OSPF, to its transfer from the GPC to the uplink station, to the uplink to the satellite and then finally to its acquisition by the GESS receiver. As the transmission of the navigation message is a key element of any GNSS system, allowing the user to correctly calculate an accurate position, it is important to ensure the timeliness and robustness of this transmission-reception process. Besides the navigation message latency, one of main purposes of this paper is to provide an assessment of the Broadcast Navigation Message Performance in terms of Signal In Space User Ranging Error (SISRE), namely the clock and ephemeris errors conveyed by the broadcast message. In particular the analyses presented in this study have been focused on the most recent GIOVE-B data (March – September 2009). Moreover, a specific section has been devoted to a detailed analysis of the statistical distribution of the broadcast navigation message errors.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	3017 - 3024
Cite this article:	Galluzzo, G., Sánchez-Gestido, M., Gonzalez, F., Binda, S., Radice, G., Hedqvist, A., Swinden, R., "GIOVE-B Navigation Message Performance Analysis and Signal in Space User Ranging Error (SISRE) Characterization," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 3017-3024.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In