As part of the research of modern movements of the Earth’s crust, an analysis of 7 high-precision methods for calculating GNSS positions was carried out for the convergence of their daily mean coordinates. Based on Euclidean distances, regular and maximal discrepancies between coordinates of different methods are given. According to the coordinates in the ITRF, 5 methods are stood out with regular coordinate discrepancies <1 mm, and individual maximum discrepancies up to 30 mm. The other two methods have regular discrepancies in coordinates up to 2 cm, and the maximum differences reach 1 m. For a group of stations global coordinates transformation into a local reference frame leads to the effect of coordinate stabilization and increases their relative precision in the time series. As a result of such procedure, the level of maximum coordinate discrepancies between the methods decreased to 46%. Moreover, one of the methods of calculating coordinates has improved its convergence with the other methods by 80%. Based on the Euclidean distance method, the quality of the raw data for each station was evaluated. Thus, there is a group of 8 stations, for which the convergence of coordinates in different methods are approximately at the same level, and 2-3 times better than for the other 2 stations.

In Central Asia, the level of geodynamic displacements of the Earth's crust does not significantly exceed the accuracy of their measurement methods. Therefore, we need to choose the most accurate methods of calculating coordinates for cosmogeodetic stations. In this work, based on the data of 8 days of GPS measurements at 10 stations, 7 sets of average daily geocentric XYZ coordinates were calculated using different methods. To determine the positions, we used 3 calculation methods in the GAMIT/GLOBK program, 2 methods in the Bernese GNSS software, and 2 web services. To estimate the differences between 7 coordinate sets, we used parameters based on the Euclidean distance between these coordinate samples. The difference analysis of all pair combinations for 7 coordinate sets was carried out by 3D radius vectors, individual coordinate axes, and individual observation stations. The calculations showed that the positioning accuracy and precision depended not only on the coordinate calculation method but also on the selected reference frame. Methods using the international terrestrial reference frame (ITRF) provide station positions with regular deviations of <2 mm and individual deviations up to 5 cm. Methods using the regional and "point" reference frames have regular discrepancies for individual coordinates up to 2 cm and maximum deviations up to 1 m. Converting XYZ coordinates to UVW with the local reference frame reduces the difference between UVW sets by at least 25%. Due to the spatial orientation relative to the studied stations, the X (U) coordinate is reproduced 2-3 times with smaller deviations than other coordinates. The average deviation level of coordinate sets can be an indicator of the quality of conditions for receiving a GNSS signal at one station. We have identified the station group that has a coordinate deviation level several times lower than other stations. Doi: 10.28991/CEJ-2023-09-02-04 Full Text: PDF