GIOVE-A and GIOVE-A2 Orbit Testing Results

E. Rooney, M. Unwin, G. Gatti, M. Falcone, S. Binda, M. Malik and D. Hannes

Abstract:	The space element of Europe’s Galileo system has commenced with two planned demonstration satellites GIOVE-A and GIOVE-B, prior to the four In-Orbit- Verification (IOV) Galileo satellites, scheduled for launch in 2009. GIOVE-A was built by Surrey Satellite Technology Ltd (SSTL), launched in December 2005, and has been broadcasting prototype Galileo signals to the world since early 2006. During this period, much has been learnt from the experimental campaign and the measurements taken on the ground, and the signal-inspace specification has been brought into the public domain on ESA’s website. Recent activities include the detailed investigation into the end-to-end Galileo signal channel. A payload test-bed at SSTL has been used by ESA and SSTL for comparison with the signals received from orbit to investigate a slight distortion of some of the broadcast signals. Experimentation is underway to compensate for this distortion using flexibility within the signal generator supplied by Thales Alenia Space (formerly Laben) that is anticipated ultimately to yield a signal-in-space with a significantly lower distortion level. Another significant activity is the closing of the navigation message loop. GIOVE-A has commenced transmission of the navigation message generated by the Galileo Processing Centre using GIOVE-A orbit and clock data calculated from measurements from the Galileo experimental sensor station (GESS) monitor station network. Furthermore GIOVE-A signals will continue to be broadcast in support of the ongoing clock characterisation campaigns and further signal-in-space experiments. Following the success of GIOVE-A, and to assist with contingency planning prior to IOV launch, ESA awarded a further contract to SSTL in March 2007 to commence procurement activities for the GIOVE-A2 satellite. GIOVE-A2 is largely based upon the GIOVE-A design, but incorporating minor design corrections based on lessons learnt from the first satellite. Design commonality will permit SSTL to manufacture the satellite to a very tight timescale, to be ready for launch as early as mid 2008. ESA and SSTL are investigating the capability of modifying GIOVE-A2 to broadcast MBOC signals to permit early experience of these new signals in anticipation of Galileo.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	467 - 477
Cite this article:	Rooney, E., Unwin, M., Gatti, G., Falcone, M., Binda, S., Malik, M., Hannes, D., "GIOVE-A and GIOVE-A2 Orbit Testing Results," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 467-477.
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