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

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.