GPS + Galileo Single-frequency Relative Positioning with Low-cost Receivers

Cécile Deprez and René Warnant

Abstract:	During the past decade, Galileo (Europe) and BeiDou (China) satellite systems have been expanded, bringing their total number of in-orbit satellites to 26 and 35, respectively. In combination with GPS (USA), the redundancy of observations has increased, improving the precision, availability and robustness of satellite positioning worldwide. Low-cost single-frequency receivers could largely benefit from these combinations of GNSS, as for instance in the case of safety-of-life applications, for which system failure may be critical. In this contribution, we tested the possibility of improving the positioning performances of single-frequency lowcost receivers by using a tight combination of Galileo E1 + GPS L1 frequency. We evaluated positioning precisions of u-blox EVK M8T receivers, which cost a few hundred USDs, in multi-GNSS relative positioning based on code and phase double differences (DD). We compared the results obtained with those of geodetic receivers, which cost thousands of USDs. The use of a unique-pivot satellite for both constellations in GPS L1 + Galileo E1 double differences introduces differential receiver hardware delays between GPS and Galileo, also called Inter-System Biases (ISBs). We studied both ISBs between low-cost receivers and ISBs between lowcost and geodetic receivers in an ISBs-float short baseline double difference model. We then quantified the positioning precision improvement brought by multi-GNSS single-frequency ISBs-fixed solutions with respect to ISBs-float solutions and multi-GNSS double differences where ISBs are ignored.
Published in:	Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018) September 24 - 28, 2018 Hyatt Regency Miami Miami, Florida
Pages:	3956 - 3966
Cite this article:	Deprez, Cécile, Warnant, René, "GPS + Galileo Single-frequency Relative Positioning with Low-cost Receivers," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 3956-3966. https://doi.org/10.33012/2018.16078
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