The Basic Performance Assessment Of GNSS Open Service Signals

Global Navigation Satellite System is an important infrastructure of Navigation,positioning and timing,in recent years obtained the rapid development of Satellite Navigation System of performance evaluation is an important guarantee of the System run continuously,at the same time,also for the commanding heights of the GNSS System,because of the differences of various aspects reason,at present,the System of performance evaluation results are on their own conditions,therefore,in order to ensure the use of all kinds of users convenient,goal of open interoperability is truly achieved,It is very necessary to monitor and evaluate the current four satellite navigation systems accordingly.Based on this,a series of work has been carried out in three aspects: the accuracy of GNSS signal-in-space,the correction effect of broadcast ionospheric model and the performance of pseudo-range single point positioning.The main research contents and work of this paper are as follows:1.The current constellation and running state of GNSS are introduced in detail;The temporal and coordinate reference frames are described.The temporal and spatial reference frames are of great significance to the monitoring and evaluation and are the scale to measure the evaluation accuracy.The importance of the temporal and spatial reference frames and the impact on GNSS interoperability are pointed out.2.Accuracy analysis of the space of GNSS signals,signal-in-space continuity,availability,the precision of the spatial signal and the space three aspects such as the abnormal signals were evaluated,the results show that signal in the space continuity and usability,BDS-3 was slightly better than the BDS-2,GLONASS in addition to the individual stars,overall accuracy of the GPS and Galileo less;In terms of spatial signal accuracy,Galileo has the highest accuracy,BDS-3 is at the same level as GPS,and GLONASS has the lowest accuracy.In terms of spatial signal anomalies,GPS mainly enhanced L2P(Y)signal,while BDS mainly enhanced B3 I signal.3.The BDGIM,GPSK8,Ne Quick and BDSK8 broadcast ionospheric models in the Beidou region are described,and the revision effect of GNSS ionospheric model is evaluated based on the CODE global ionospheric grid diagram.The results show that the correction accuracy of BDGIM is the highest,and the correction effect of Nequick is better than that of GPSK8 in middle latitude and high latitude.At the same time,the correction accuracy of the Ne Quick model in each latitude zone is roughly equal,As for the impact of geomagnetic storms on the ionospheric model in the same latitude zone,it is found that the variation trend is the same,and it will have a greater impact in the middle latitude region.4.Based on the i GMAS data,the GNSS data quality and pseudo-range single point positioning performance were evaluated and analyzed,and the SNR performance and variation trend of each frequency point of each system were roughly similar;Multipath,BDS-2 are associated with high Angle of system error and the BDS B2 a has good inhibition,the four GPS multipath error of frequency from 0.19 m to 0.23 m,Galileo E1 multipath error compared with the other two frequency point there is a larger error,reached 0.26 m,GLONASS two frequency points of multipath error precision fairly;In terms of positioning,the three-dimensional position RMS of BDS,GPS(except L2C)and Galileo static pseudo-range single point positioning is better than 5m,and GLONASS is better than 10 m.