Optimization of GNSS data processing methods in Yunnan and surrounding areas

The observation data of 347 global IGS stations from 2015 to 2016 are divided into seven subnets for calculation,with using GAMIT／GLOBK software developed by the Massachusetts institute of technology, and a fixed frame of reference is obtained to calculate the coordinates of 35 GNSS reference stations of Yunnan and surrounding areas.The horizontal direction and vertical direction of the RMS of the measuring station are within 0.7 mm and 0.3 mm,The horizontal coordinate repeatability accuracy is within 5 mm, while the vertical coordinate repeatability accuracy is mostly within 2.5 cm,The comparison with the measured station coordinates, baseline length and horizontal velocity field calculated under ITRF2014 shows that there is systematic error in the station coordinates, the difference in the horizontal direction is less than 8.5 mm, and the difference in the vertical direction is less than 3 cm,the baseline length difference is within 2 mm, and the horizontal velocity field has a difference of millimeter in value, and the direction is basically the same.