An Evaluation of Various Ionospheric Error Mitigation Methods used in Single Frequency PPP

Precise Point Positioning (PPP) using dual frequency GPS receivers is capable of providing centimetre level point positioning accuracy anywhere around the world, without the need for a base station. However, when using single frequency GPS receivers, the accuracy of the positioning decreases, particularly in the height component. One main factor for this degradation in accuracy is the unmodeled ionospheric error. This paper investigates the performance of three different ionospheric error mitigation methods used in single frequency PPP in the Australian Region. They are the GRAPHIC (GRoup And PHase Ionospheric Correction) algorithm, the Global Ionospheric Maps (GIMs) and the Klobuchar model. Numerical results show that the GRAPHIC and GIMs methods are able to provide point positioning accuracy better than 1m for session duration less than an hour using geodetic quality single frequency receivers. For 12 to 24 hours data sets, the positioning accuracy can be as good as <0.1m.