The ESA "GNSS+" Project. Inter-satellite Ranging and Communication Links in the Frame of the GNSS Infrastructure Evolutions

M. Sánchez, J.A. Pulido, F. Amarillo, J.L. Gerner

Abstract:	The GNSS+ project has been developed by DEIMOS Space under ESA technical coordination and funding and it is aimed at investigating alternative and innovative technologies and methods in the satellite navigation area to improve the current navigation systems and future evolutions of GNSS systems. These improvements are focused on the following fields: a) Improvement of orbit and clock determination data, b) Reduction of ground segment infrastructure, c) Enhancement of satellite autonomy, d) Increment of update rate of navigation data, e) Reduction of operational cost To accomplish such challenging objectives it is envisaged the utilization of inter-satellite ranging and communication links and auxiliary on-ground and on-board orbit and clock determination processing capabilities. The analyzed architecture is based on the ability of the: 1) Satellites to perform spacecraft-to-spacecraft double-frequency pseudorange measurements 2) Ground stations and satellites to perform MEO-GSS and GSS-MEO double frequency pseudorange measurements. 3) On-ground orbit and clock determination function to process optimally the observables described in the two bullets above. 4) On-board orbit and clock determination function to process a sub-set of the observables described above, sufficient to ensure a certain minimum level of performances, enabling spacecraft autonomy In order to assess quantitatively the system design, a sophisticated SW tool has been developed, which generates synthetic measurements, and determines from them the orbit and clock parameters. In addition the project has devoted a significant effort to the evaluation of the inter-satellite ranging signal, and to transmission and reception units, including antennas.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	2538 - 2546
Cite this article:	Sánchez, M., Pulido, J.A., Amarillo, F., Gerner, J.L., "The ESA "GNSS+" Project. Inter-satellite Ranging and Communication Links in the Frame of the GNSS Infrastructure Evolutions," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 2538-2546.
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