03. GNSS CORS data and precise ephemeris for building a ground control network in geodesy works

Abstract

In this study, data from two national GNSS CORS stations (CRRS and DNRS) together with precise ephemeris data are used to calculate the coordinates of 14 points of the GNSS network in Phu Yen, Dak Lak, Khanh Hoa. The research results show that the point position errors of 14 GNSS points have a uniform, averaging about 4.1 cm. TN4-02-11 is the worst point which is 5.0 cm of the positioning error. TN4-02-04 and TN4-02-08 are the best points that are 3.1 cm of the positioning error. The TN4-02-03 - TN4-02-04 is the worst baseline which the relative mean square errors and azimuth errors being 1/189458 and 1.21”, respectively. It can be seen that, although the GNSS network has long baselines (the longest is nearly 464 km), due to using precise
ephemeris in processing data, the GNSS network still ensures the service requirements for surveying, designing and constructing work. In Vietnam, the system of national GNSS CORS stations has been completed and used. Besides, precise ephemeris is supported by International GNSS Service. So that the accuracy of the GNSS network fully meets the tasks of geodetics in general, and geodesy in particular.