Data Quality Evaluation And Research On Velocity Determination Based On Multi-GNSS

At present,GNSS navigation and positioning technology has been very advanced,and the accuracy of navigation and positioning has been able to reach centimeter or even millimeter level.Intensive IGS monitoring sites and CORS sites have been built wroldwide,which is a technical guarantee for high-precision GNSS measurement.In addition,these intensive monitoring stations also meet the requirements for high precision position and speed in the fields of meteorological observation,airborne gravity measurement,and instantaneous crustal deformation monitoring.High precision GNSS data quality is the prerequisite for high precision navigation and positioning,so it is very necessary to evaluate the quality of the observation data before GNSS data processing,and it can provide reference experience for the later data processing.Nowdays,several commonly used GNSS speed measuring methods can be divided into position difference method,original Doppler observation velocity and carrier phase to derive Doppler observation velocity according to the observation object,and there are single station and relative velocity measurement according to the velocity measurement mode.This paper focuses on the two problems mentioned above.The main contents and achievements of this paper are as follows:(1)First,it introduced the necessity and the important application areas of data quality evaluation.On this basis,it introduces a GNSS data quality processing software TEQC.It introduces several major functional modules,running environment of TEQC,and the operating process of interface TEQC,and introduces what information is contained in the result files generated by TEQC,and analyzes the results of data quality evaluation in theory.This paper also analyzes the well-known software of several GNSS data quality evaluation compiled by experts and institutions at home and abroad for the shortage of TEQC.For example,the GFZRNX software of the German geoscience center can switch between RINEX 2/3 versions,so it can be used with TEQC.In addition,I can also apply the application to the SNR statistics.(2)Second,this paper studied the theory of several common GNSS velocity measurement methods mainly.A multi-GNSS combined velocity measurement model based on the original Doppler observation value and the carrier phase to derive Doppler observation value is set up.In combination with the experimental data,a set of GNSS software compiled by myself is used to calculate the data,and analysises the accuracy of the original Doppler observation velocity,carrier phase to derive Doppler observation velocity and a combine of both two observations velocity of multi-GNSS.The results show that the multi-GNSS combined to measure velocity increases the number of available satellites,improves the geometric structure of the satellite,increases the accuracy and reliability of the velocity measurement,and the multi-GNSS system combination can significantly improve the accuracy of the original Doppler velocity measurement and phase difference derived from the Doppler velocity measurement,at the same time,it can also improve the precision of the original Doppler observation velocity measurement and carrier phase to derive Doppler observation velocity measurement;the combination of the original Doppler and the phase derivation of the Doppler observation value can effectively improve the velocity measurement accuracy of the GNSS single system,but the combination effect of the multi system can improve the velocity measurement accuracy in a degree.