GNSS Data Quality Analysis Algorithm Research And Software Implementation Of Beidou Ground-based Augmentation System

With the increasing use of the Global Navigation Satellite System(GNSS)in various fields,the requirements for providing high-precision position and timing services for GNSS are becoming higher and higher,while GNSS Observations such as pseudorange,carrier phase,navigation messages are the basis for providing high-precision GNSS position and timing services.Therefore,data quality analysis and evaluation of observations such as pseudorange,carrier phase,and navigation message are guarantees for the subsequent provision of high-quality services.The Beidou ground-based augmentation system consists of base stations,data centers,and communication network.It is an important infrastructure for the Beidou satellite navigation system to provide high-precision location services.The base station of the Beidou Ground Augmentation System National Framework has been built 150.A total of 6 multi-mode multi-frequency receivers and antenna devices provided by domestic manufacturers have been adopted.The performance indicators and stability of these domestically produced devices are different from those of GPS,so that the quality of output data(observation data and navigation message)is deviated,which leads to the complexity of data quality analysis of each satellite navigation system.The data quality is the premise of the subsequent high-quality service provided by Beidou ground-based augmentation system,and the data quality analysis method of Beidou ground-based augmentation system is carried out.Research is necessary to make up for the gap in the data quality analysis of the Beidou ground-based augmentation system,which is of great significance to ensure the continuous and stable operation of the Beidou ground-based augmentation system.Based on the above requirements,this thesis are aiming at the design and software implementation of GNSS data quality analysis algorithm for Beidou ground-based augmentation system,the multi-GNSS multi-frequency data quality analysis method is studied systematically,and the evaluation scheme for the accuracy of navigation data of each system is studied,and the Beidou ground augmentation system framework network is utilized.Base station observation data and navigation message,research and analysis of the observation data quality of the Beidou ground-based augmentation system frame network reference station,developed a GNSS data quality analysis software for the Beidou ground-based augmentation system.The main research contents and results of this thesis are as follows:(1)On the basis of studying the data quality analysis index calculation methods such as data integrity,multipath effect,signal to noise ratio,cycle slip ratio and PDOP,The effects of height angle,receiver type and base station distribution on data integrity are studied,the difference between the GPS/BDS/GLONASS multipath effects of the same base station is compared and analyzed,and the differences of multipath effects are analyzed from the aspects of base station distribution,receiver type,constellation type and frequency point.(2)The advantages and disadvantages of single-frequency,dual-frequency and three-frequency cycle slip detection are studied from the aspects of timeliness,engineering realization and detection accuracy.The wavelet analysis method and the polynomial fitting method are compared and analyzed.The results show that the wavelet analysis method can detect smaller cycle slips,but it is affected by the length of the time series and the timeliness is poor.The polynomial fitting method is easy to implement,but The detection accuracy of small cycle jump is not high,and it is prone to misjudgment.The dual-frequency comparison analysis of the ionospheric residual method and the M-W combination method shows that both of them can detect the cycle slip of more than 0.5,but cannot detect when the specific jumps of the L1 and L2 frequencies occur.Cycle slip,and the ionospheric residual method needs to accurately detect the cycle slip under the condition that the ionospheric delay changes slowly and the multipath effect is small.The three-frequency cycle slip detection without geometric distance carrier phase combination method is studied,and the optimal combination coefficient is deduced.Several combination coefficients with small comprehensive influence factors are given.The geometric distance phase combination method can theoretically detect 0.1,the insensitive cycle slip problem for a specific ratio combination coefficient,tri-band non-geometric distance carrier phase combination with M-W combination method can effectively detect such insensitive cycle slip.(3)The GPS/BDS/GLONASS broadcast ephemeris accuracy evaluation algorithm is studied.Based on the GBM precision ephemeris and clock difference products provided by MGEX,the URE of the three systems is evaluated,and the accuracy of the three-system broadcast ephemeris is statistically analyzed.The results show that the average URE 7-day average of all satellites in GPS is 0.7 meters,the average 7-day URE of all satellites in BDS is 1 meter,and the average URE 7 days of all satellites in GLONASS is 2.5 meters.(4)Data quality analysis of the data from the base stations of the Beidou ground-based augmentation system framework network from the aspects of data integrity,signal-to-noise ratio,cycle-slip ratio and multipath effect.The results show the observation data quality of the ground-based augmentation system 91% domestic frame network reference station(O/Slips>200,MP1<0.5,MP2<0.65,MP3<0.65)meets the requirements for the construction of the Beidou ground-based augmentation system.The specific influence of GPS L2 signal change on the observation data of the Beidou ground-based augmentation system base station is analyzed.(5)Develop a GNSS data quality analysis software for the Beidou ground-based augmentation system.The software includes multi-base station real-time data transmission monitoring,real-time multi-mode multi-frequency data quality analysis,real-time evaluation of global and Chinese regional PDOP,and evaluation of satellite navigation system broadcasts.The functions of the ephemeris accuracy and other functions ensure the continuous and stable operation of the Beidou ground-based augmentation system.