Research On The Establishment Method Of Regional Reference Rrame

The establishment and maintenance of the earth reference frame has always been a hot and difficult subject in the field of surveying and mapping science.ITRF is currently recognized as the most accurate and widely used global reference frame in the world.However,the number of ITRF network reference stations is very limited,and the global distribution is uneven.Obviously,it is not conducive to the development of regional navigation and mapping applications,so it is established and maintained.The respective regional reference frames are very necessary.The establishment and maintenance of the research regional reference frame is of great scientific and practical significance to economic and social development.This article summarizes the theory and method of establishing and maintaining a regional reference frame,which is embodied in a set of stations with precise coordinates and velocity fields.Research is carried out around the establishment and maintenance of key technologies for regional reference frames,involving the movement of the earth's center of mass,the establishment of reference frame conversion models,and the conversion of time-varying reference frames.The main work and contributions of the paper are:1)Explained the global and regional reference frames,introduced the development status of several representative geodetic reference frames,and summarized the theory and method of establishing and maintaining the regional reference frame based on CORS,including the establishment of regional reference frames and global,The relationship between national and regional reference frames and the non-linear dynamic maintenance of regional reference frames were described.2)Introduce the current commonly used methods of noise reduction of nonlinear signals and their application status.Using IGS data to invert geocentric motion,a noise reduction method for geocentric motion time series based on variational mode decomposition(VMD)and energy entropy is proposed.Power spectrum is used to analyze the geocentric motion law and establish a model.The research results show that the noise reduction method based on VMD and energy entropy has a good noise reduction effect on the geocentric motion time series.The signal-to-noise ratio after noise reduction is between 52 and 59 d B,which is better than the noise reduction of EMD and EEMD.Method: There are two-year,annual and half-year periodic movements in all directions of the geocentric movement,and the annual periodic movement is the most significant.3)Analyze the relationship between coordinate reference frames,and elaborate the current solution method of reference frame conversion parameters.On the basis of solving the problem of large rotation angle frame conversion parameters,the Rodrigue matrix model is based on the fact that the nonlinear equations between the parameters and the initial scale values cannot be corrected,and an improved Rodrigue matrix model is proposed.The analysis results show that the accuracy of the scale parameter solved by the improved common point side length method is higher than that of the 2-norm method;the improved Rodrigue matrix model does not require linearization,and can accurately correct and improve the accuracy of the scale parameter.The method is not only suitable for Large rotation angle reference frame conversion is also applicable to small rotation angle reference frame conversion.4)Mainly introduces the reference frame conversion method that takes into account the time series changes,and deduces the three commonly used coordinate frame conversion models.Using ITRF data to solve and compare the conversion accuracy of each method,the results show that the conversion results and accuracy of the simultaneous conversion of epoch-after-frame,frame-first-epoch and epoch frame are the same;the effect of epoch conversion on coordinate conversion Far greater than the frame conversion,so the acquisition of high-precision velocity field is still the bottleneck of achieving high-precision conversion between reference frames.