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
非差模糊度经过未校准硬件延迟小数部分(fractional cycle bias,FCB)产品改正后恢复整周特性,能够显著缩短精密单点定位(precise point positioning,PPP)的初始化时间。服务端采用非组合模型估计FCB产品时,由于电离层误差的影响,原始频...非差模糊度经过未校准硬件延迟小数部分(fractional cycle bias,FCB)产品改正后恢复整周特性,能够显著缩短精密单点定位(precise point positioning,PPP)的初始化时间。服务端采用非组合模型估计FCB产品时,由于电离层误差的影响,原始频点L1和L2的FCB无法准确分离,因此提出一种基于消电离层组合FCB产品的非组合PPP部分模糊度固定方法。由于传统服务端消电离层组合FCB产品算法与用户端非组合模糊度固定算法具有一致性,可采用星间单差的宽巷和原始频点模糊度构建窄巷模糊度,利用消电离层组合FCB产品进行分步模糊度固定。采用全球120个MGEX(multi-GNSS experiment)测站作为服务端生成消电离层组合FCB和非组合FCB产品,再选取全球未参与服务端解算的10个测站进行评估验证。实验结果表明,相对于使用传统非组合FCB的模糊度固定方法,静态情况下,所提方法收敛精度平均提升25.0%,收敛时间缩短21.1%;仿动态条件下,所提方法收敛精度平均提升26.7%,收敛时间缩短17.9%。展开更多
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.
