As one of the Analysis Centers(AC)of the International GNSS Service(IGS),Wuhan University(WHU)has been contributing to the IGS by providing ultra-rapid as well as rapid orbit and clock solutions for the established GP...As one of the Analysis Centers(AC)of the International GNSS Service(IGS),Wuhan University(WHU)has been contributing to the IGS by providing ultra-rapid as well as rapid orbit and clock solutions for the established GPS and GLONASS since 2012.In the same year,the IGS initiated the Multi-GNSS Experiment(MGEX)to support the analysis of the emerging GNSS systems and prepare the IGS for Multi-GNSS,which includes GPS,GLONASS,the European Galileo system,the Chinese Beidou Navigation Satellite System(BDS),the Japanese Quasi-Zenith Satellite System(QZSS)and the Indian Regional Navigation Satellite System(IRNSS/NaVIC).The major products,i.e.,orbits,Earth Orientation Parameters(EOPs),satellite clock as well as attitude have also been provided by WHU since 2012.More recently,WHU has engaged the third reprocessing of IGS for generating the highly accurate station coordinates as inputs for establishment of the International Terrestrial Reference Frame(ITRF)2020 during 2019—2020.This article presents the recent major advancements of the IGS AC at Wuhan University,including precise products,real-time products,bias products,antenna phase center calibration,and the non-linear motion modeling for GNSS Reference Stations.展开更多
Since the frst pair of BeiDou satellites was deployed in 2000,China has made continuous eforts to establish its own independent BeiDou Navigation Satellite System(BDS)to provide the regional radio determination satell...Since the frst pair of BeiDou satellites was deployed in 2000,China has made continuous eforts to establish its own independent BeiDou Navigation Satellite System(BDS)to provide the regional radio determination satellite service as well as regional and global radio navigation satellite services,which rely on the high quality of orbit and clock products.This article summarizes the achievements in the precise orbit determination(POD)of BDS satellites in the past decade with the focus on observation and orbit dynamic models.First,the disclosed metadata of BDS satellites is presented and the contribution to BDS POD is addressed.The complete optical properties of the satellite bus as well as solar panels are derived based on the absorbed parameters as well the material properties.Secondly,the status and tracking capabilities of the L-band data from accessible ground networks are presented,while some low earth orbiter satellites with onboard BDS tracking capability are listed.The topological structure and measurement scheme of BDS Inter-Satellite-Link(ISL)data are described.After highlighting the progress on observation models as well as orbit perturbations for BDS,e.g.,phase center corrections,satellite attitude,and solar radiation pressure,diferent POD strategies used for BDS are summarized.In addition,the urgent requirement for error modeling of the ISL data is emphasized based on the analysis of the observation noises,and the incompatible characteristics of orbit and clock derived with L-band and ISL data are illuminated and discussed.The further researches on the improvement of phase center calibration and orbit dynamic models,the refnement of ISL observation models,and the potential contribution of BDS to the estimation of geodetic parameters based on L-band or ISL data are identifed.With this,it is promising that BDS can achieve better performance and provides vital contributions to the geodesy and navigation.展开更多
The Fractional Cycle Bias(FCB)product is crucial for the Ambiguity Resolution(AR)in Precise Point Positioning(PPP).Different from the traditional method using the ionospheric-free ambiguity which is formed by the Wide...The Fractional Cycle Bias(FCB)product is crucial for the Ambiguity Resolution(AR)in Precise Point Positioning(PPP).Different from the traditional method using the ionospheric-free ambiguity which is formed by the Wide Lane(WL)and Narrow Lane(NL)combinations,the uncombined PPP model is flexible and effective to generate the FCB prod-ucts.This study presents the FCB estimation method based on the multi-Global Navigation Satellite System(GNSS)precise satellite orbit and clock corrections from the international GNSS Monitoring and Assessment System(iGMAS)observations using the uncombined PPP model.The dual-frequency raw ambiguities are combined by the integer coefficients(4,−3)and(1,−1)to directly estimate the FCBs.The details of FCB estimation are described with the Global Positioning System(GPS),BeiDou-2 Navigation Satellite System(BDS-2)and Galileo Navigation Satellite System(Galileo).For the estimated FCBs,the Root Mean Squares(RMSs)of the posterior residuals are smaller than 0.1 cycles,which indicates a high consistency for the float ambiguities.The stability of the WL FCBs series is better than 0.02 cycles for the three GNSS systems,while the STandard Deviation(STD)of the NL FCBs for BDS-2 is larger than 0.139 cycles.The combined FCBs have better stability than the raw series.With the multi-GNSS FCB products,the PPP AR for GPS/BDS-2/Galileo is demonstrated using the raw observations.For hourly static positioning results,the performance of the PPP AR with the three-system observations is improved by 42.6%,but only 13.1%for kinematic positioning results.The results indicate that precise and reliable positioning can be achieved with the PPP AR of GPS/BDS-2/Galileo,supported by multi-GNSS satellite orbit,clock,and FCB products based on iGMAS.展开更多
基金National Natural Science Foundation of China(Nos.42030109,42074032)Program for Hubei Provincial Science and Technology Innovation Talants(No.2022EJD010)。
文摘As one of the Analysis Centers(AC)of the International GNSS Service(IGS),Wuhan University(WHU)has been contributing to the IGS by providing ultra-rapid as well as rapid orbit and clock solutions for the established GPS and GLONASS since 2012.In the same year,the IGS initiated the Multi-GNSS Experiment(MGEX)to support the analysis of the emerging GNSS systems and prepare the IGS for Multi-GNSS,which includes GPS,GLONASS,the European Galileo system,the Chinese Beidou Navigation Satellite System(BDS),the Japanese Quasi-Zenith Satellite System(QZSS)and the Indian Regional Navigation Satellite System(IRNSS/NaVIC).The major products,i.e.,orbits,Earth Orientation Parameters(EOPs),satellite clock as well as attitude have also been provided by WHU since 2012.More recently,WHU has engaged the third reprocessing of IGS for generating the highly accurate station coordinates as inputs for establishment of the International Terrestrial Reference Frame(ITRF)2020 during 2019—2020.This article presents the recent major advancements of the IGS AC at Wuhan University,including precise products,real-time products,bias products,antenna phase center calibration,and the non-linear motion modeling for GNSS Reference Stations.
基金sponsored by the National Natural Science Foundation of China(41974035,42030109)Yong Elite Scientists Sponsorship Program by CAST(2018QNRC001).
文摘Since the frst pair of BeiDou satellites was deployed in 2000,China has made continuous eforts to establish its own independent BeiDou Navigation Satellite System(BDS)to provide the regional radio determination satellite service as well as regional and global radio navigation satellite services,which rely on the high quality of orbit and clock products.This article summarizes the achievements in the precise orbit determination(POD)of BDS satellites in the past decade with the focus on observation and orbit dynamic models.First,the disclosed metadata of BDS satellites is presented and the contribution to BDS POD is addressed.The complete optical properties of the satellite bus as well as solar panels are derived based on the absorbed parameters as well the material properties.Secondly,the status and tracking capabilities of the L-band data from accessible ground networks are presented,while some low earth orbiter satellites with onboard BDS tracking capability are listed.The topological structure and measurement scheme of BDS Inter-Satellite-Link(ISL)data are described.After highlighting the progress on observation models as well as orbit perturbations for BDS,e.g.,phase center corrections,satellite attitude,and solar radiation pressure,diferent POD strategies used for BDS are summarized.In addition,the urgent requirement for error modeling of the ISL data is emphasized based on the analysis of the observation noises,and the incompatible characteristics of orbit and clock derived with L-band and ISL data are illuminated and discussed.The further researches on the improvement of phase center calibration and orbit dynamic models,the refnement of ISL observation models,and the potential contribution of BDS to the estimation of geodetic parameters based on L-band or ISL data are identifed.With this,it is promising that BDS can achieve better performance and provides vital contributions to the geodesy and navigation.
基金The National Key Research and Development Program of China(2018YFC1505102)the Programs of the National Natural Science Foundation of China(41774025,41731066)+2 种基金the Special Fund for Technological Innovation Guidance of Shaanxi Province(2018XNCGG05)the Special Fund for Basic Scientific Research of Central Colleges(CHD300102269305,CHD300102268305)the Grand Projects of the BDS-2 System(GFZX0301040308)supported this study.
文摘The Fractional Cycle Bias(FCB)product is crucial for the Ambiguity Resolution(AR)in Precise Point Positioning(PPP).Different from the traditional method using the ionospheric-free ambiguity which is formed by the Wide Lane(WL)and Narrow Lane(NL)combinations,the uncombined PPP model is flexible and effective to generate the FCB prod-ucts.This study presents the FCB estimation method based on the multi-Global Navigation Satellite System(GNSS)precise satellite orbit and clock corrections from the international GNSS Monitoring and Assessment System(iGMAS)observations using the uncombined PPP model.The dual-frequency raw ambiguities are combined by the integer coefficients(4,−3)and(1,−1)to directly estimate the FCBs.The details of FCB estimation are described with the Global Positioning System(GPS),BeiDou-2 Navigation Satellite System(BDS-2)and Galileo Navigation Satellite System(Galileo).For the estimated FCBs,the Root Mean Squares(RMSs)of the posterior residuals are smaller than 0.1 cycles,which indicates a high consistency for the float ambiguities.The stability of the WL FCBs series is better than 0.02 cycles for the three GNSS systems,while the STandard Deviation(STD)of the NL FCBs for BDS-2 is larger than 0.139 cycles.The combined FCBs have better stability than the raw series.With the multi-GNSS FCB products,the PPP AR for GPS/BDS-2/Galileo is demonstrated using the raw observations.For hourly static positioning results,the performance of the PPP AR with the three-system observations is improved by 42.6%,but only 13.1%for kinematic positioning results.The results indicate that precise and reliable positioning can be achieved with the PPP AR of GPS/BDS-2/Galileo,supported by multi-GNSS satellite orbit,clock,and FCB products based on iGMAS.
