Noise Analysis And Periodic Study Of Coordinate Time Series Data In CORS Station

The large amount of observation data accumulated by global IGS base stations and regional continuous operation reference stations(CORS)provides a rich source of data for geodesy and geodynamics research.The base station coordinate time series data obtained by high-precision GNSS data processing software can reflect the continuity and stability of the station.However,the lack of understanding of the widely existing noise information and seasonal cycle changes in the coordinate timing directly affects the accuracy of the coordinate solution.For example,in previous studies,it was assumed that only white noise in the coordinate time series would cause the position and velocity estimation error of the base station to be too small;the selected coordinate timing length is not enough to cause the base station elevation direction coordinate to be insufficient for periodic analysis.The solution error is too large.Based on this background,this paper selects the observation data of 16 stations from Hong Kong CORS station from May 2014 to August 2017 for 40 months,and the CORS coordinate time series data obtained by GAMIT/GLOBK software for data processing.Using different methods to comprehensively analyze the noise characteristics and periodic features in coordinate timing,it has the scientific problems of obtaining high precision Hong Kong CORS station position and motion speed accuracy,improving the crustal deformation monitoring accuracy in Hong Kong and promoting the study of block motion in South China.Certain research significance.The main research contents are as follows:(1)According to the acquisition of coordinate time series of Hong Kong CORS station,the use method and data processing flow of GAMIT/GLOBK software are studied,and the detailed baseline solution strategy and network adjustment scheme are designed.The results show that the single-day solution of the coordinates obtained by data processing can reach millimeter precision.(2)For the abnormal point in the coordinate sequence of the Hong Kong CORS station,the appropriate gross error elimination method is used for processing.For the case of missing data,the cubic polynomial interpolation method is used for interpolation,and the coordinate timing consistent with the trend term of the original coordinate time series is obtained.Finally,zero-average processing is performed,and a coordinate time series with uniform sampling and zero-mean characteristics is obtained.(3)The method of power spectrum analysis is used to obtain the 0.5-year and 1-year period items of the three coordinate components of most reference stations in the coordinate time series of Hong Kong CORS station.The least squares method is used to invert the spectral index.By analyzing the spectral index values,it is determined that the CORS station coordinate time series contains not only pure white noise,but also colored noise,and the colored noise is mainly flicker noise and random walk noise.(4)The maximum likelihood estimation method is used to analyze the CORS station coordinate time series under 14 noise models.According to the optimal noise evaluation criterion,the optimal noise model of the Hong Kong CORS station is determined mathematically,and the noise characteristics are found to be diversified.The influence law of different noise models on parameter estimation is analyzed.The linear velocity of each CORS station under the optimal noise model is obtained,and the velocity field in the horizontal direction of the Hong Kong CORS station is established.(5)Wavelet multiresolution analysis is used to analyze the coordinate time series in the elevation direction of Hong Kong CORS station from the perspective of time domain and frequency domain.The results show that the position change of CORS station in the elevation direction has large summer variation and small winter variation.Seasonal features.According to the principle of wavelet denoising,hard threshold denoising and soft threshold denoising are performed on the coordinate timing in the elevation direction,and the difference between them is analyzed according to the noise quality evaluation index.