Research On Interpolation And Extrapolation Of Precision Ephemeris In Post Processed Kinematic

Real-time kinematic,which is based on carrier phase observations,is a real-time dynamic positioning technology and has an important position in the fields of GPS research and application.It can obtain real-time position of moving objects by establishing wireless communication links between reference stations and mobile stations.In the absence of real-time positioning,GPS dynamic positioning post-processing can be used,which is a dynamic relative positioning technique for post-processing with carrier phase observations.It does not require a real-time data communication chain and can collected data back to the room for processing.The advantage of GPS dynamic post-processing is not only to avoid the possible problem,but also use of more sophisticated error models and precision ephemeris.The interval of 15min's ephemeris epoch,including satellite position and satellite clock error,is provided by IGS station.In fact,we need 10 seconds,5 seconds,1 second or even higher sampling rate.So improved precision ephemeris interpolation to reduce the error of dynamic post-processing is the key means.This paper introduces the research status,principle and algorithm of dynamic post processing,explains the error term and the correction method to reduce the measurement accuracy.The Lagrange interpolation,Newton interpolation and Chebyshev interpolation model are studied and calculated in this paper.Aiming at the problem of Longge phenomenon in the application of the above three interpolation methods in precision ephemeris interpolation,the sliding interpolation algorithm is used to improve the accuracy of precision ephemeris interpolation.The main work of this paper is as follows:(1)In this paper,the Chebyshev interpolation method is studied,and the relationship between the interpolation order and the number of sample points,the position of the interpolation point,the interpolation order and the interpolation interval are studied.The accuracy of the model is obtained.The results of interpolation based on the improved interpolation algorithm of three kinds of interpolation models can meet the requirements of GPS dynamic post-processing.The three improved models have the same interpolation accuracy when the interpolation order is the same.In terms of interpolation efficiency,the Chebyshev polynomial is optimal,followed by the Newton polynomial,the Lagrangian polynomial is the lowest.(2)In this paper,the extrapolated interpolation algorithm is used to solve the problem of interpolation blind field.When the extrapolated interpolation method is used to solve the problem,the precision ephemeris is simply extrapolated from the polynomial And extrapolate the length of extrapolations.The results show that the extrapolation accuracy is related to the selection of polynomial order and decreases with the increase of extrapolated epoch.