Robust power spectrum estimation on height time series of national CORS stations

In order to find periodic motion characteristics of height time series clearly, the methods of robust least square iteration and power spectrum estimation are used to analyze height time series of Chinese 6 IGS tracking stations lasting nearly 11 years. The accurate main period item and amplitude of height direction motion of base stations are isolated using the power spectrum estimation method. With sequential robust iteration other periods and amplitudes are isolated. Reference station height motion is got more clearly through analyzing the seasonal changes and long-period term items. It has nearly one year period motion and the second main period item which exceeds one year. The semi-year period item has only small proportions.