Performance evaluation of GPS and GLONASS systems, combined and individually, in precise point positioning.

The aim of this paper is to analyse the performance of the GLONASS (Global'naya Navigatsionnay Sputnikovaya Sistema), GPS (Global Positioning System) and the combined use of both systems at different latitudes, by using the service Precise Point Positioning CSRS-PPP. For this purpose, 16 stations from the IGS (International GNSS Service) network were selected, from which were used the GNSS data in RINEX format of August 2014 and edited by using TEQC (Translation, Editing and Quality Check) to obtain files with intervals of 30 and 45 minutes, which only contain GPS data, GLONASS data and both systems data. The estimated coordinates in CSRS-PPP were compared with the reference coordinates obtained from the site of ITRF (International Terrestrial Reference Frame), enabling the accuracy calculation of the PPP by using GPS and GLONASS data, separated and combined. After the accuracies calculation for each day of august, outliers were detected and discarded by using boxplot method with the R software. It was found that GPS and GLONASS when used jointly, for all the stations, have enabled more accurate results. In addition, one may noticed the GLONASS potentiality, which presented superior performance when compared to GPS in most stations.