Latest Acheivments in GIOVE Signal and Sensor Station Experimentations

J. Giraud, V. Borrell, M. Crisci

Abstract:	The GALILEO ground mission segment (GMS) will include a worldwide network of stations providing the measurements required to compute the navigation message and to check the integrity of signal broadcast by the satellite constellation. An early characterization of these measurements is therefore a key activity in order to consolidate and validate the overall segment design and performance. Thus, as part of the GIOVE Mission program led by the European Space Agency (ESA), dedicated experimentations have been conducted since mid-2006. In this frame, an entire experimental ground segment has been deployed (processing centre and sensor stations), and dedicated investigations allowed the validation of a first set of performances. As of 2008, GIOVE system is completed with the following enhancements : launch of GIOVE-B spacecraft and transmission of its SIS (in particular, CBOC modulation), extension of the initial network of 13 stations with 3 additional stations equipped with Novatel GIOVE/Galileo receivers bringing a fruitful diversity, optimization of several stations antennas, and maturity of the operation of the ground infrastructure. This new step achieved enabled to devise new activities at signal and station level, widening the spectrum of GMS performance and design aspects addressed in the experimentations. On the one hand, an advanced level of consolidation has been reached on receiver performance. First the performance of the new CBOC modulation scheme has been assessed in real conditions, demonstrating the clear improvements in the measurement noise, and therefore confirming the theoretical expectations. Then, the receiver ability to acquire the GNSS signals has been analyzed to issue figures of merit. Finally, the new experimental Novatel Galileo Station has been characterized and compared to original one. On the other hand, at segment and system performance level, key aspects regarding integrity determination has been deeply investigated. First, stations raw data was used to characterize the efficiency of the hatch filter applied at integrity algorithm input to mitigate station measurement noise. Then, using data collected on the network equatorial stations, it was possible to characterize the impact of ionospheric scintillation on receiver phase measurements used in the integrity determination algorithm (loss of lock, and measurement noise increase possibly causing data discarding). This paper proposes an overview of these latest fields of experimentation. In particular, for each of them, methods applied, achieved results, and impact on Galileo performance validation are described.
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:	3025 - 3036
Cite this article:	Giraud, J., Borrell, V., Crisci, M., "Latest Acheivments in GIOVE Signal and Sensor Station Experimentations," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 3025-3036.
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