GPS Solutions

, Volume 17, Issue 1, pp 63–73 | Cite as

Galileo single frequency ionospheric correction: performances in terms of position

  • Benoît BidaineEmail author
  • Matthieu Lonchay
  • René Warnant
Original Article


For GPS single frequency users, the ionospheric contribution to the error budget is estimated by the well-known Klobuchar algorithm. For Galileo, it will be mitigated by a global algorithm based on the NeQuick model. This algorithm relies on the adaptation of the model to slant Total Electron Content (sTEC) measurements. Although the performance specifications of these algorithms are expressed in terms of delay and TEC, the users might be more interested in their impact on positioning. Therefore, we assessed the ability of the algorithms to improve the positioning accuracy using globally distributed permanent stations for the year 2002 marked by a high level of solar activity. We present uncorrected and corrected performances, interpret these and identify potential causes for Galileo correction discrepancies. We show vertical errors dropping by 56–64 % due to the analyzed ionospheric corrections, but horizontal errors decreasing by 27 % at most. By means of a fictitious symmetric satellite distribution, we highlight the role of TEC gradients in residual errors. We describe mechanisms permitted by the Galileo correction, which combine sTEC adaptation and topside mismodeling, and limit the horizontal accuracy. Hence, we support further investigation of potential alternative ionospheric corrections. We also provide an interesting insight into the ionospheric effects possibly experienced during the next solar maximum coinciding with Galileo Initial Operation Capability.


Galileo Positioning Ionospheric correction Single frequency NeQuick model Data ingestion 



The work presented is part of B. Bidaine’s PhD thesis in progress under a F.R.S.-FNRS fellowship (Belgian National Fund for Scientific Research). We would like to acknowledge S. Radicella and B. Nava from ICTP in Trieste for providing us NeQuick latest version; R. Prieto-Cerdeira and R. Orus from ESA/ESTEC for the TEC data as well as the official NeQuick version for Galileo.


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Benoît Bidaine
    • 2
    Email author
  • Matthieu Lonchay
    • 2
  • René Warnant
    • 1
  1. 1.Geomatics UnitUniversity of Liège (ULg)LiègeBelgium
  2. 2.Geomatics UnitUniversity of Liège (ULg) / Fund for Scientific Research - FNRSLiègeBelgium

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