Periodicity Systematic Error Analysis of GPS in Nonlinear Variations of Station Coordinates

Analysing the mechanism of nonlinear variations in GPS stations coordinates time series is an effective way to improve the coordinates accuracy of GPS stations. The constellation design characteristic of GPS may cause the periodic variations of GPS stations coordinates and affect the precision of GPS stations coordinates. In order to analyze the systematic error of the GPS, the spectrum analysis was applied to detect the periodic terms of the GPS and VLBI vertical coordinates time series in the selected 6 amalgamated stations, the amplitude and initial phase of periodic terms were extracted. The annual terms were commonly found in the coordinates time series of GPS and VLBI, the annual terms’ changing trend of GPS and VLBI were basically same, and the systematic error was commonly found between GPS and VLBI. Meanwhile, it was also found that the systematic error of the semi-annual terms exist between the two technologies in some amalgamated stations, which may be related to the systematic error of GPS itself and the false periodic terms caused by the data’s quality problems.