Estimation of relative ionospheric delay by GNSS Algorithm for Accuracy and Safety

In this paper, a GNSS software package named GAFAS (GNSS Algorithm For Accuracy and Safety) is introduced. GAFAS is a general-purpose software package developed since 2005. It is written in C/C++ language being purposed to build diversified GNSS infrastructure and user applications. Currently, GAFAS is upgrading its capability in medium/long baseline integer ambiguity resolution for more accurate ionospheric delay estimation. To verify the validity of its concept, an experiment was performed with real measurements.