Abstract
Abstract One of the main error sources in GNSS positioning comes from the ionosphere, an atmospheric layer that stays in the signal path between the satellite and the receiver. For single frequency positioning, the ionospheric effects can be minimized by using an ionospheric model e.g. Klobuchar or NeQuick G. These models are respectively associated to GPS and Galileo systems through their navigation messages, which broadcast coefficients that describe the worldwide ionospheric behavior, and the calculated ionospheric delay is then applied in the pseudorange observations. In this paper, it is presented a comparison between these two models in multi-GNSS (GPS and Galileo) single frequency point positioning, considering two Brazilian stations at different magnetic latitudes, and covered months of weak and strong ionospheric activity from 2013 to 2018. The results indicate a better performance of NeQuick G model compared to the Klobuchar. Considering all the analyzed periods and stations, Klobuchar improves the positioning accuracy in 16% and 50% in periods of weak and strong ionospheric activity, respectively, while NeQuick G improves the accuracy in 31% and 55%.
Highlights
Global Navigation Satellite System (GNSS) based positioning has been increasingly used for a wide range of purposes
Considering all the periods and stations, the largest improvement in positioning error is of 65%, for POAL station, October 2014, when the tridimensional RMS drops from 16.9 m when no ionospheric model is applied to 6.0 m with NeQuick G model
Two Brazilian stations located in different parts of the country were selected, and the analyzed period covered a time gap of 6 years, picking up days from 2013 to 2018, considering seasonal and long period variations that affect the ionosphere
Summary
Global Navigation Satellite System (GNSS) based positioning has been increasingly used for a wide range of purposes. It was initiated in the seventies, when the first GPS (Global Positioning System) satellites were launched by the United States Department of Defense (US DoD) (HoffmannWellenhof, Lichtenegger and Wasle 2008). Galileo is a new GNSS initiated in the nineties, developed and maintained by the European Union for civil purposes. The ionosphere is one of the main error sources in signal propagation. The range of the ionospheric error is proportional to the Total Electron Content (TEC) along the signal path, which varies depending on observation latitude, local time, season, geomagnetic activity, solar cycle, and other anomalies and irregularities (Seeber 2003). Different methods can be adopted to minimize the ionospheric effect in positioning, such as the use of dualfrequency technique, augmentation system, global/regional TEC map, or an ionospheric model
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