Reseach On Real-time Precise Point Positioning Based On BeiDou Augmentation And Its Application In Mining Surface Monitoring

GNSS Real-Time Precise Point Positioning(RT-PPP)technology can obtain real-time centimeter-level positioning and decimeter navigation with only a single GNSS receiver.The technology is researching theoretically and testing currently,not a wide range or regional applications,in the military,engineering,agriculture and other fields have a wide range of application prospects and market.This paper focuses on the GPS+BDS RT-PPP technology based on Beidou enhanced,including the PPP error correction model,real-time cycle detection and repair of un-difference carrier observations,GPS+BDS precise orbit determination and forecasting,real-time satellite clock error filtering,real-time PPP robust filtering model,GPS+BDS multi-system RT-PPP.The main research content and results are as follows:(1)The characteristics and order of the three types of error sources of RT-PPP,and the error correction model or elimination method are studied.Unlike traditional PPP,RT-PPP requires special consideration of real-time orbit,real-time clock error,ERP and BDS PCO/PCV errors,especially the latter two are more likely to be ignored.(2)The nature and conditions of the conventional ionospheric-free combined cycle-slip detection method are analyzed,ie the ionospheric delay must be kept stable or slowly.A real-time cycle-slip detection method based on MW combination / ionospheric delay method is proposed for dual-frequency un-difference carrier observations.This method can be used for real-time cycle-slip detection of low-sampling un-difference observation data for 30 s.In order to ensure the success rate of real-time cycle-slip detection,this method can be used to detect cycle-slip with other combinations of observations.At the same time,increasing the setting of the satellite cutoff angle and improving the forecast accuracy of ionospheric delay,can effectively improve the success rate of the existing cycle-slip method.(3)Aiming at the observation value of the triple-frequencies un-difference carrier,a real-time cycle-slip detection and repair method based on the code-phase combination / geometry-free phase combination based on the ionospheric delay correction is proposed.The three combinations do not have the insensitive cycle-slip combination and the linearity related.At the same time,considering the influence of ionospheric delay on the accuracy of geometry-free phase combination,the geometry-free phase combination observation is modified by sliding window method to reduce the influence of ionospheric delay.The results show that any combination of different sampling rates and different types of satellites can be realized,and only the least squares solution of round estimation can be directly rounded to repair the cycle-slip,no complex search matching process.(4)The method and strategy of ambiguity fixed resolution are studied,and 55 IGS / MGEX tracking stations are used for precise orbit determination.The results show that the ambiguity fixed method of fractional deviation method can improve the accuracy of satellite precise orbit determination,43% increase in GPS satellites,and 32%,82% and 54% of BOD GEO,IGSO and MEO satellites,respectively;the orbit accuracy of GPS satellites is better than 3cm,the orbit accuracy of BDS GEO satellites better than 3m,IGSO and MEO better than 10 cm.(5)The influence of the solar radiation pressure(SRP)model on the determination and prediction of the orbit is studied.The ECOM 5 and ECOM 9 parameters are used to analyze and forecast the orbit of GPS and BDS.The results show that the ECOM 9 parameters is 10% higher than that of the ECOM 5 parameters model for orbit determination and prediction of GPS satellites.The accuracy of the two kinds of pressure models is similar,and it is also feasible to use the ECOM pressure model for BDS orbit determination.The orbital accuracy of 6h GPS satellites is better than 5cm,the orbital accuracy of 6h BDS GEO satellites better than 3m,IGSO and MEO better than 20 cm.(6)Aiming at the problem of correlation between the observation,the quality control model of the Square Root Information Filter(SRIF)is improved and the robust factor selection of the SRIF is demonstrated.The simulation results show that the improved method can reasonably choose the combination of various outliers and fix them accurately.At the same time,81 IGS / MGEX tracking station data for satellite real-time clock error filter solution and quality control.The results show that the accuracy of GPS real-time satellite clock error is better than 0.2ns,which of BDS is better than 0.3ns.As a whole the clock accuracy to achieve real-time centimeter-level precise positioning.(7)Aiming at the characteristics of accuracy and correlation between PPP carrier and code measurement,a standardized Kalman filter based on residual vector is proposed,which can effectively overcome the high precision observation that is not sensitive to outliers,and it can effectively overcome its correlation by reducing the residual vector correlation and iterative calculation.The results show that the influence of the outliers of the single satellite on the position parameter is less than 1 mm,which can effectively eliminate or reduce the influence of the abnormal outliers on the localization solution,which is based on the residual equivalent weight factor Kalman filter quality control model.(8)The accuracy of real-time PPP is studied,using GBM post,CUM-U ultra-rapid and real-time precision products with GPS and GPS+BDS combination,respectively.The results show that the GBM post,CUM-U ultra-rapid and real-time precision products get 10 cm positioning accuracy,need 15-20 min,40min and 2-3h convergence,respectively;to get the plane is better than 2cm,the elevation is better than 5cm positioning accuracy respectively,need 1h,1.5-2h and 4-5h convergence,respectively;to get mm-level positioning accuracy,respectively,3-4h,4-5h and 5-6h convergence,respectively;the same time,in the case of enough GPS satellites,single GPS and GPS+BDS combination of convergence accuracy is basically the same,but GPS+BDS combination can speed up the convergence rate.(9)The mine observation conditions better CORS station and the occlusion area of the measured data RT-PPP solution respectively.The results of CORS station show that the accuracy of 1cm or even mm level can be obtained after 4-5h convergence and the accuracy of mine surface real-time monitoring can be meeting.The results show that GPS+BDS can improve the positioning accuracy and convergence speed greatly under the condition of few GPS satellites.