Investigation of reliability of the variance covariance matrices obtained from GIPSY-OASIS II v6.4 software for precise point positioning

In recent years Precise Point Positioning (PPP) technique is one of the most important subjects in Geomatic Engineering. PPP technique needs only one Global Navigation Satellite Systems (GNSS) receiver thus users have preferred it instead of traditional relative positioning technique for several applications. Nowadays, scientific software generally has been used for PPP solutions and the Variance covariance (VCV) matrices estimated from software are very optimistic. The formal errors estimated from VCV matrices have major effects on statistical interpretation. VCV matrices derived from GNSS processing software play important role for deformation analysis and scientists sometimes need to scale VCV matrices. In this study, 10 continuously operating International GNSS Service (IGS) reference stations have been considered for 11 days dated 2014. All points have been analyzed by GIPSY-OASIS II v6.4 scientific software. It is aimed to estimate scale factor for the PPP results obtained from GIPSY-OASIS II v6.4 with considering different session durations as 2, 4, 6, 8, 12 and 24 hours. According to the results, the values of the scale factors raise depending on the raises in respect of session duration