Performance Comparison of Selected Ionospheric Models for GNSS Positioning

An evaluation of ionospheric corrections derived from the two global total electron content (TEC) maps, Neustrelitz DLR/GIM and Center for Orbit Determination in Europe CODE/GIM, for the mitigation of ionospheric threats to precise GNSS positioning, has been carried out. Investigations to both models have been performed using the following empirical procedures: calculation of station coordinates for each observation epoch; calculation of the time series of interpolated TEC values for all observation epochs using both the CODE and DLR maps; calculation of TEC values from the recorded GPS observations at selected stations; comparison and analysis of all three sets of TEC values, Rate of TEC (ROT) values and the time series of station coordinates to identify source of anomalous signals. The paper presents the first results of investigations using GPS data recorded during a period with quiet ionosphere and a period with high ionospheric irregularities.