Analysis of GNSS Accuracy of Relative Positioning and Precise Positioning Based on Online Service

Nowadays, Global Positioning System (GPS) has been used effectively in several engineering applications for the survey purposes by multiple disciplines. Web-based online services developed by several organizations; which are user friendly, unlimited and most of them are free; have become a significant alternative against the high-cost scientific and commercial software on achievement of post processing and analyzing the GPS data. When centimeter (cm) or decimeter (dm) level accuracies are desired, that can be obtained easily regarding different quality engineering applications through these services. In this paper, a test study was conducted at EUROPE network; in order to figure out the accuracy analysis of the most used web based online services around the world (namely OPUS, AUSPOS,, CSRS-PPP, TRIMBLE RTX). These services use relative and precise point positioning (PPP) solution approaches. In this test study, the coordinates of fourteen IGS stations were estimated by using different online services and by The International Terrestrial Reference Frame (ITRF) web site which it taken as a reference from 24-hour GPS data in 1/1/2015 set and then the coordinate differences between the online services solution and the International Terrestrial Reference Frame ITRF result. From the evaluations, it was seen that the results for each individual differences were less than 12 mm regarding relative online service, and less than 31 mm regarding precise point positioning service. The accuracy analysis was gathered from these coordinate differences and standard deviations of the obtained coordinates from different techniques and then online services were compared to each other. The results show that the position accuracies obtained by associated online services provide high accurate solutions that may be used in many engineering applications and geodetic analysis