Investigation of GNSS velocities accuracies using combinations of different campaign numbers and measurement times

In this research, a study was carried out on determining parameters affecting the horizontal and vertical velocity accuracy of the GNSS sites. Some data combinations consisting different number of campaign, measurement times and periods created using six TUSAGA-Active stations and all data were processed with the GAMIT/GLOBK software to obtain velocities and accuracies. All results were analyzed changing the parameters step by step and visualized to making interpretation easily. The RMSE values for each combination were used for all comparisons and interpretations. In combinations of 2 campaigns, it was observed that RMSE values for measurement time ≥ 4 (MT≥4) improved when the second campaign measure was fixed and the first campaign measure and year interval were increased. When the first campaign is kept constant, measurement time of the second campaign and the time between campaigns are increased (at least two hours measurement period), it is seen that the interval between campaigns should be 4 years for the RMSE<1. In combinations of three campaigns, the RMSE values improved as time between campaigns and measurement times increased. However, the increase in the number of campaigns was not as effective as the time between campaigns and measurement time in the improvement of the RMSE values. As the time between campaigns increases, the RMSE values for different campaign numbers improve. This shows that it is possible to achieve high velocity accuracy by measuring 1 more campaign GNSS observation at a GNSS site have being the GNSS data belong the past years.