GNSS Precision Single-point Positioning Troposphere Delay Correction Scheme Study

Tropospheric delay is a key factor that interferes with the positioning accuracy of GNSS(Global Navigation and Positioning Satellite System,GNSS).In the process of GNSS satellite signals passing through the atmosphere,there will be time delay and path tortuous problems due to the interference of atmospheric refraction,which will cause the propagation delay of GNSS signals.The conventional way to address tropospheric delay errors is to implement corrections with the aid of a tropospheric delay model.At present,tropospheric empirical models are mainly constructed on the basis of global or large regions,and there will be some systematic errors if they are applied in small regions.Therefore,it is necessary to construct a regional tropospheric model by means of model function method,so as to better correct the tropospheric delay and improve the positioning accuracy.With the Caofeidian District as an example,the regional atmospheric refractive index model is constructed based on the analysis of sounding data and data fitting of relevant meteorological parameters by seasons.The four-season regional tropospheric zenith delay model is obtained by integral,and the simulation analysis is carried out.It is concluded that the summer tropospheric zenith delay model has good accuracy,which can be used as a general tropospheric model for the four seasons.This model is introduced into the GAMP(GNSS Analysis software for Multi-constellation and multi-frequency Precise positioning)tropospheric zenith delay model module,and the experimental study is carried out using Precise Point Positioning(Precise Point Positioning,PPP).Finally,the zenith delay models such as the constructed CFDQ model and the Estimate ZTD model are compared and explored.The research indicates that the CFDQ model shows obvious accuracy advantages in the static precision single-point positioning experiment in the Caofeidian District,and the accuracy of the Estimate ZTD model is close followed,the SAAS model had the worst accuracy.Judging from the comparison between the CFDQ model and the Estimate ZTD model,the difference between the coordinate residuals in the X and Y directions is only0～2.5cm;it is found that there is an error of 0～1.2cm by observing the residual error of the Z coordinate.For a more direct and comprehensive study of the positioning accuracy of the three tropospheric models at the station,the internal and external coincidence accuracy is calculated successively.It is found that the CFDQ model has the highest accuracy of inner and outer coincidence,and the optimal outer coincidence accuracy of the plane is 1.22 cm,the optimal outer coincidence accuracy of the elevation is 2.25 cm,and the optimal inner coincidence accuracy is 0.01 cm.Therefore,it can be proved that the CFDQ model is suitable for the description of the tropospheric atmosphere in the Caofeidian District.At the same time,this model has a more significant advantage in the accuracy of delay error correction in the relevant experimental process in the Caofeidian District compared with other zenith delay models.Figure 10;Table 16;Reference 57...