Performance Analysis Of Quasi-Zenith Satellite System

With the development of GNSS technology and the continuous improvement of various applications,the performance of satellite navigation systems has attracted the attention of users,and has become the focus of competition in various systems.QZSS is a brand new regional satellite navigation system built by Japan.It was officially launched on November 1,2018.Its coverage includes the eastern part of China and the South China Sea.It can be used as a supplement to the Beidou system in China.Study the performance evaluation method for the QZSS system and use the measured data for verification to provide support for improving the satellite navigation system evaluation indicator system.At the same time,it is very necessary for China to use QZSS system,and it can also provide some reference for the development of China Beidou system.The main research contents and results of the thesis are as follows:1.This paper summarizes the research background and the research status of global satellite navigation system monitoring and evaluation,QZSS satellite navigation system,expounds the research purpose and main content of this paper,and summarizes the composition and function of QZSS.The STK software is used to simulate the QZSS and GPS satellite constellation,and the coverage of QZSS is analyzed,and the number of visible satellites and positional accuracy factor(PDOP)of the GPS system is enhanced.2.This paper analyzes the running status of QZSS system PNT service by analyzing QZSS running status report and QZSS broadcast ephemeris parameters,and discusses the management strategy of QZSS system for satellite running status.The analysis shows that QZSS can predict the interruption 7-10 days in advance,and the planned interruption time will have a surplus,and the service can be quickly restored after the interruption.Satellite orbits and satellite clocks are adjusted during the interruption.This paper analyzes the relationship between multipath error and elevation angle of QZSS satellite and compares it with Beidou system.The results show that the QZSS satellite multipath error is negatively correlated with the satellite elevation angle;the QZSS satellite multipath error size and variation are basically the same as those of the same orbit type Beidou satellite.3.In this paper,the global ionospheric map(GIM)released by CODE is used to evaluate the performance of QZSS broadcast ionospheric correction model in the service area,and compared with GPS ionospheric correction parameters,Beidou regional model and BDGIM.The results show that the QZSS broadcast ionosphere model has the best correction effect in high latitudes.In the mid-latitude region,the BDGIM has the best correction effect,followed by the QZSS model;the QZSS model in the equatorial region has the best correction effect.4.Based on the precise ephemeris,this paper evaluates the broadcast orbit accuracy,broadcast clock error and SISRE of the QZSS.The QZSS satellite ephemeris releases a group every hour,and the orbital jump will also occur once every hour.The R,T,and N directions are generally decimeter-sized,and the individual moments exceed 1 meter.The broadcast clock error fluctuates within 4ns and the overall accuracy is better than 3ns.SISRE fluctuates within 3m,and the overall accuracy of the test period meets the SISRE?2.6m(95%)specified in the QZSS-PS.In addition,it uses SLR data to analyze QZSS ephemeris accuracy.5.This paper uses the measured data of IGS station to analyze the enhancement of GPS by QZSS,in terms of positioning accuracy,continuity and availability.The results show that in the core service area,QZSS can enhance the GPS service performance of high satellite elevation,and the higher satellite elevation,the more obvious the effect.