Improvement Of IGMAS Observation Quality And Research Of High-precision Ionospheric Monitoring

The international GNSS Monitoring and Assessment System(iGMAS)is an open information platform for monitoring and evaluating the operation status and performance index of GNSS system,providing GNSS observations,precision satellite orbit and clock,coordinate and velocity of station,global ionosphere model and so on.For the service of iGMAS system,high quality observations is the basic guarantee.The dissertation mainly includes improving iGMAS observation quality and precise monitoring ionosphere,conducts research deeply as follows:(1)Present a new methodology to improvement of observation quality.It proposes to equip a wave-absorbing shield around the iGMAS stations to improve the local observation environment,and then improve the quality of GNSS observation on the base of the station establishment.It designs the structure of the wave-absorbing shield suiting for tracking station.Comparing the result of eight iGMAS station in domestic before and after equiping the wave-absorbing shield,the method can weaken the multipath effectively and improve the single point position accuracy of GNSS.(2)A new high-accuracy and continuous ionosphere monitor method is proposed based on the static ionosphere pierce point(IPP)of BDS GEO satellite.Based on the static characteristic of ionospheric IPP of GEO satellites,a new high-accuracy and continuous ionosphere monitor method is proposed and studied deeply.Demonstrated the characteristics of the method using the observations from eight MGEX and iGMAS stations which distributed globally.Analyzed the monitoring accuracy for combination of BDS B1/B2,B1/B3,B2/B3 frequecies.The highest accuracy combination is verified the validitied by IGS ionosphere grid model.Analyzed the changing rules of TEC from static IPP.The results of ionospheric TEC monitoring for 3 years of fixed puncture point in the southern hemisphere,equator and northern hemisphere are given.(3)The method of global ionosphere model with higher-order ionospheric is studied.Analyzed the the effect and correction method of ionosphere high-order,established high-precision global ionospheric delay model using measurements before and after correction.Compared with IGS ionospheric products,the precision of global ionospheric delay model is improved to a certain extent using the high-order correction observation.(4)Analyzed the long-term variation of BDS DCBCompared and analyzed the long term stability of DCB of BD GEO/IGSO/MEO,GPS Block IIR-M/Block IIR/Block IIF,GLONASS satellite DCB with data of 1400 days.It is found that the DCB solution of the receivers has annual periodic variation.The changing factor is involved with yearly changing of ionosphere TEC with the preliminary analysis.