Ionospheric corrections for precise positioning with single-frequency GNSS receivers, a long distance away from the nearest network receiver

Abstract

We intend to present results of a study where precise ionospheric corrections have been generated and then used to assist Global Navigation Satellite System (GNSS) positioning with data from high-end single-frequency receivers. The data used in the tests were from CORSnet-NSW (Australia) and from the NGS CORS (USA). The motivation has been twofold: (a) to use new techniques for estimating corrections for the ionospheric delay in L1, with moderate levels of scintillation and travelling ionospheric disturbance (TID), and test them in single-frequency positioning solutions; (b) to help make the most of good L1-only receivers that can be considerably less expensive than dual-frequency ones. The emphasis is on wide-area L1-only applications, such as point positioning, supported by a sparse CORS-type network where the stations are separated by distances of up to several hundred kilometres. In order to maximise the accuracy and consistency of the ionospheric corrections for single-frequency precise GNSS users, the following approach will be considered: the TOMION tomographic model of the ionospheric electron content, which simultaneously solve the main model unknown parameters in a wide area GNSS network (like carrier phase ambiguities and zenith tropospheric delays). This will be adopted in order to provide the main “lineal” ionospheric corrections to the users (following e.g. Colombo O.L., Hernandez-Pajares M., Juan J.M. & Sanz J. (2002) Wide-area, carrier-phase ambiguity resolution using a tomographic model of the ionosphere, Navigation, 49(1), 61-69). Moreover, the potential benefits for single-frequency precise GNSS users of adapting existing models of the predominant ionospheric waves (the Medium Scale Travelling Ionospheric Disturbances, MSTIDs) will be specifically assessed in this work taking into account recent findings (Hernandez-Pajares M., Wielgosz P., Paziewski J., Krypiak-Gregorczyk A., Stepniak K., Bosy J., Kaplon J., Hadas T., Orus-Perez R., Monte-Moreno E., Yang H., Garcia-Rigo A. & Olivares-Pulido G. (2015) New approaches in Medium Scale Travelling Ionospheric Disturbances modelling, Geophysical Research Abstracts, Vol. 17, EGU General Assembly 2015).