The Analysis of GPS Data in Different Observation Periods Using Online GNSS Process Services

Abstract

The usability and the accuracy of internet-based position determination services which have gained importance
 in recent years is one of the up-to-date subjects of studies. Online processing services have more advantages
 than commercial and scientific software; since they are easy to use, require less experience and free because
 they get quick results. In this study, GPS observation files in rinex format belonging to 6 stations were
 evaluated using Auspos, Magic-GNSS and Opus services then the results were obtained. Three systems
 showed the similar results for the results obtained according to 24-hour measurement period. In the second
 study, observation files were divided into 12, 6 and 2 hour groups and after the results were obtained they were
 compared to 24-hour results. According to the reports, it was seen that the accuracy decreased as the
 observation period got shorter. In all three systems, 24 and 12-hour observation accuracy occurs in cm
 measures. In 6 and 2 hour periods where the observation period is shorter, accuracy value reaches to 3-4 cm.
 According to these results, it is seen that although it generally depends on observation period, internet-based
 position determination services sustain adequate accuracy for basic geodetic network application that the
 topographical engineering needs.