Analysis of the EGNOS quality parameters during high ionosphere activity

Today, one of the key problems of global navigation satellite systems (GNSS) positioning with single-frequency receivers is the variability of the ionospheric delay. Satellite-based augmentation systems (SBAS) could overcome this problem since they generate the real time (updated every 5 min) ionospheric delay corrections but these can be unstable during space weather disturbances. The aim of this article is to present the quality of European Geostationary Navigation Overlay Service (EGNOS) positioning during two one-week observation periods in March 2015 and September 2017, in which the last two strongest geomagnetic storms took place. In order to perform a reliable analysis, the study was conducted at four IGS stations in different geographical latitudes located near the EGNOS availability border. The analyses and graphs of important navigation parameters were made using Septentrio Post Processing SDK and PEGASUS software which were developed in accordance with relevant aviation guidelines. The results showed an improvement in the quality of positioning in 2017, which could indicate positive impact of the new EGNOS software release. Nevertheless, even with the latest software, EGNOS positioning may still be unstable during geomagnetic storms, especially in the northern and southern borders of service coverage.