| By the end of 2019,the basic networking satellites of Beidou navigation satellite navigation system have been launched and officially provide basic navigation services to the world.It can be predicted that BDS-2 and BDS-3 will coexist in the future.BDS-2 and BDS-3 have the same constellation structure,and they all have the GEO /MEO / IGSO satellites.BDS-3 adds B1 C and B2 a frequency points which are compatible with GPS / Galileo satellite.With the continuous development of BDS-3satellite and the completion of BDS-3 satellite networking,it is very important to comprehensively evaluate the performance of BDS-3 satellite.At the same time,by comparing the pseudo-range multipath errors of BDS-2 and BDS-3,it is found that there is a systematic error in the pseudo-range multipath errors of BDS-2 satellite,which decreases with the increase of satellite altitude angle.This error is called the pseudo-range multipath error at the satellite end.The existence of the pseudo-range multipath deviation at the satellite end of BDS seriously affects the positioning accuracy of BDS.This paper mainly analyzes the data quality of all BDS-3 satellites at present,then studies the pseudo-range multipath deviation of BDS-2 GEO / IGSO /MEO satellites and its correction model,and finally applies the model to BDS single-frequency precise single point positioning experiment for verification,the research methods and conclusions are as follows:(1)In this paper,a set of BDS/GNSS observation data quality analysis software is developed based on data integrity rate,signal-to-noise ratio,multipath effect and ionospheric delay.The quality evaluation and analysis of BDS2/BDS-3 satellite multi-frequency observation data are realized.And the software can process the observation data of the GPS/GLONASS/Galileo system at the same time.Through the software,the quality of BDS-3 GEO/IGSO/MEO satellite observation data was analyzed from four aspects: data integrity rate,SNR,pseudo-range multipath deviation and ionospheric delay.The processing results were compared with the same type of BDS-2 satellite and the GPS/Galileo overlap frequencies.The quality of BDS-3 satellite has been found to be comparable to that of the GPS/Galileo satellite.(2)This paper analyzes the correlation between the pseudo-range multipath deviation and the elevation of BDS satellite.The influence of time and station position on the pseudo-range multipath deviation also has been analyzed.Based on the analysis of the correlation between the pseudo-range multipath deviation andsatellite elevation of BDS-2 IGSO/MEO satellite,this paper proposes to establish a three-frequency correction model of BeiDou IGSO/MEO satellite observation data by using the method of weighted piecewise curve modeling.The experimental results show that the pseudo-range multipath deviation between IGSO and MEO satellite is obviously weakened after correction.For the pseudo-range multipath deviation of GEO satellite,this paper proposes a modeling method based on Tikhonov regularization.The RMS of the modified MP sequence of GEO satellite decreased by 35.9%/29.8%/35.8% on the frequency of B1/B2/B3 respectively.(3)In order to verify the feasibility of the pseudo-range multipath deviation correction strategy proposed in this paper,three sets of single-frequency PPP positioning schemes are designed.The results show that: by correcting the pseudo-range multipath deviation of IGSO/MEO satellite,the positioning accuracy of N/E direction is improved by 20.2%/13.4% on average,and that of U direction is improved by 62.8% on average.The positioning accuracy in the U direction will be improved to 70% while correcting the pseudo-range multipath deviation of GEO/IGSO/MEO satellites.Therefore,the modified model of the observed values of Pseudo-range observation of BDS-2 satellite proposed in this study can effectively reduce the influence of these pseudo-range multipath deviations. |
PDF Full Text Request