This research work provides an overview of the comparison of EGNOS, Global Maps
and experimental data position errors over the Southern part of the ECAC region, on the basis
of TEC values. It is well known that ionospheric conditions represent the main factor that influences
GNSS positioning accuracy at the frequency operation. The satellite signals experience a
delay when passing through the ionosphere. This delay depends on several factors such as
geographical location of the receiver, solar and geomagnetic activity, season and hours of the
day. It results in range errors that can vary from few meters to tens of meters. To overcome
this problem, augmentation system (SBAS) based on geostationary satellites support have
been developed. These systems use a grid-based model to determine the delay introduced by
the ionosphere. Since the delay magnitude depends linearly on the total number of free
electrons in the ionosphere, the delay model corresponds to values of Total Electron Content
(TEC). Performances of such systems are challenged in areas of large ionospheric variability
like those found at low latitude or under space weather events, such as geomagnetic storms.
The European augmentation system is EGNOS. The objective of the present study is to
evaluate on a quantitative level EGNOS performance on both delay (TEC) and positioning
domains by adequate comparisons with independent data and the use of well provided tools
like gLAB.
