Global Navigation Satellite System precise positioning using carrier phase measurements requires reliable ambiguity resolution.It is challenging to obtain continuous precise positions with a high ambiguity fixing rate...Global Navigation Satellite System precise positioning using carrier phase measurements requires reliable ambiguity resolution.It is challenging to obtain continuous precise positions with a high ambiguity fixing rate under a wide range of dynamic scenes with a single base station,thus the positioning accuracy will be degraded seriously.The Forward-Backward Combination(FBC),a common post-processing smoothing method,is simply the weighted average of the positions of forward and backward filtering.When the ambiguity fixing rate of the one-way(forward or backward)filter is low,the FBC method usually cannot provide accurate and reliable positioning results.Consequently,this paper proposed a method to improve the accuracy of positions by integrating forward and backward AR,which combines the forward and backward ambiguities instead of positions-referred to as ambiguity domain-based integration(ADBI).The purpose of ADBI is to find a reliable correct integer ambiguities by making full use of the integer nature of ambiguities and integrating the ambiguities from the forward and backward filters.Once the integer ambiguities are determined correctly and reliably with ADBI,then the positions are updated with the fixing ambiguities constrained,in which more accurate positions with high confidence can be achieved.The effectiveness of the proposed approach is validated with airborne and car-borne dynamic experiments.The experimental results demonstrated that much better accuracy of position and higher ambiguity-fixed success rate can be achieved than the traditional post-processing method.展开更多
The integer least squares(ILS)estimation is commonly used for carrier phase ambiguity resolution(AR).More recently,the best integer equivariant(BIE)estimation has also attracted an attention for complex application sc...The integer least squares(ILS)estimation is commonly used for carrier phase ambiguity resolution(AR).More recently,the best integer equivariant(BIE)estimation has also attracted an attention for complex application scenarios,which exhibits higher reliability by a weighted fusion of integer candidates.However,traditional BIE estimation with Gaussian distribution(GBIE)faces challenges in fully utilizing the advantages of BIE for urban low-cost positioning,mainly due to the presence of outliers and unmodeled errors.To this end,an improved BIE estimation method with Laplacian distribution(LBIE)is proposed,and several key issues are discussed,including the weight function of LBIE,determination of the candidates included based on the OIA test,and derivation of the variance of LBIE solutions for reliability evaluation.The results show that the proposed LBIE method has the positioning accuracy similar to the BIE using multivariate t-distribution(TBIE),and significantly outperforms the ILS-PAR and GBIE methods.In an urban expressway test with a Huawei Mate40 smartphone,the LBIE method has positioning errors of less than 0.5 m in three directions and obtains over 50%improvements compared to the ILS-PAR and GBIE methods.In an urban canyon test with a low-cost receiver STA8100 produced by STMicroelectronics,the positioning accuracy of LBIE in three directions is 0.112 m,0.107 m,and 0.252 m,respectively,with improvements of 17.6%,27.2%,and 26.1%compared to GBIE,and 23.3%,28.2%,and 30.6%compared to ILS-PAR.Moreover,its computational time increases by 30–40%compared to ILS-PAR and is approximately half of that using TBIE.展开更多
This paper presents the technical basis for wide area real time decimetre positioning services using multiple carrier signals transmitted by future GNSS such as modernized GPS and Compass systems. The first step is to...This paper presents the technical basis for wide area real time decimetre positioning services using multiple carrier signals transmitted by future GNSS such as modernized GPS and Compass systems. The first step is to form two ionosphere-reduced extra-widelanes (EWL) that have the minimal total noise levels in cycles, considering the effects of the ionospheric and tropospheric delays, orbital error, and phase noise terms in various observational environments. The proposed three carrier ambiguity resolution approach can determine the integer ambiguities of the selected EWL signals with geometry-free and geometry- based estimations respectively over the distances of typically hundreds of kilometres. With two ambiguity-fixed EWL signals, the kinematic positioning solutions can be achieved in decimetre level accuracy. A semi-simulation method is employed to generate three frequency Compass data to demonstrate the above expected performance for decimetre positioning services. Both theoretical and experimental results have demonstrated the overall 3D root mean square accuracy of better than 15 cm obtained through with a phase smoothing process over 120 epochs. The dominating error factor in this positioning result is the residual tropospheric biases, which would become less correlated as the baselines grow beyond hundreds of kilometres. With respect to dual-frequency based precise point positioning and wide area differential positioning solutions, a major advantage of using the third frequency signals is the convergence time being shorten from tens of minutes to a few minutes. In addition, due to the instant ambiguity resolution capability, phase breaks or cycle slips no longer affect the continuity of the solutions. This reliable decimetre positioning capability introduces a significant improvement to safety-of-life, liability-critical and professional applications.展开更多
哨兵(Sentinel)-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为研究基于全球导航卫星系统多星座的低轨卫星精密定轨提供了契机。固定载波相位模糊度可提升低轨卫星的定轨精度,利用在轨实测数据研究GPS/Galileo双系统组合以及模糊度固...哨兵(Sentinel)-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为研究基于全球导航卫星系统多星座的低轨卫星精密定轨提供了契机。固定载波相位模糊度可提升低轨卫星的定轨精度,利用在轨实测数据研究GPS/Galileo双系统组合以及模糊度固定对低轨卫星运动学定轨精度的影响。分别采用欧洲定轨中心(Center for Orbit Determination in Europe,CODE)、法国国家空间研究中心(Centre National d’Etudes Spatiales,CNES)、德国地学研究中心(German Research Centre for Geosciences,GFZ)和中国武汉大学(Wuhan University,WHU)发布的观测值偏差及对应的精密星历和钟差产品开展单接收机模糊度固定。结果表明:GPS/Galileo双系统组合可明显改善定轨几何构型。双系统组合浮点解轨道三维精度优于30 mm,相对于GPS单系统提升超过20%。模糊度固定显著提升了运动学定轨精度,组合固定解轨道精度优于20 mm,相对于GPS提升30%。基于CODE、CNES和GFZ产品的GPS和Galileo单系统模糊度固定率分别优于93%和95%,WHU产品的Galileo固定率则偏低。利用卫星激光测距(satellite laser ranging,SLR)观测数据对运动学定轨结果进行检核,单系统固定解轨道SLR残差均方根误差(root mean square,RMS)为13~15 mm,双系统组合固定解RMS则达到12~14 mm,提升超过10%。展开更多
基金the National Science Fund for Distinguished Young Scholars(Grant No.41825009)the Funds for Creative Research Groups of China(Grant No.41721003)Changjiang Scholars program.
文摘Global Navigation Satellite System precise positioning using carrier phase measurements requires reliable ambiguity resolution.It is challenging to obtain continuous precise positions with a high ambiguity fixing rate under a wide range of dynamic scenes with a single base station,thus the positioning accuracy will be degraded seriously.The Forward-Backward Combination(FBC),a common post-processing smoothing method,is simply the weighted average of the positions of forward and backward filtering.When the ambiguity fixing rate of the one-way(forward or backward)filter is low,the FBC method usually cannot provide accurate and reliable positioning results.Consequently,this paper proposed a method to improve the accuracy of positions by integrating forward and backward AR,which combines the forward and backward ambiguities instead of positions-referred to as ambiguity domain-based integration(ADBI).The purpose of ADBI is to find a reliable correct integer ambiguities by making full use of the integer nature of ambiguities and integrating the ambiguities from the forward and backward filters.Once the integer ambiguities are determined correctly and reliably with ADBI,then the positions are updated with the fixing ambiguities constrained,in which more accurate positions with high confidence can be achieved.The effectiveness of the proposed approach is validated with airborne and car-borne dynamic experiments.The experimental results demonstrated that much better accuracy of position and higher ambiguity-fixed success rate can be achieved than the traditional post-processing method.
基金funded by the National Key R&D Program of China(Grant No.2021YFC3000502)the National Natural Science Foundation of China(Grant No.42274034)+2 种基金the Major Program(JD)of Hubei Province(Grant No.2023BAA026)the Special Fund of Hubei Luojia Laboratory(Grant No.2201000038)the Research project of Chongqing Administration for Marktet Regulation,China(Grant No.CQSJKJ2022037).
文摘The integer least squares(ILS)estimation is commonly used for carrier phase ambiguity resolution(AR).More recently,the best integer equivariant(BIE)estimation has also attracted an attention for complex application scenarios,which exhibits higher reliability by a weighted fusion of integer candidates.However,traditional BIE estimation with Gaussian distribution(GBIE)faces challenges in fully utilizing the advantages of BIE for urban low-cost positioning,mainly due to the presence of outliers and unmodeled errors.To this end,an improved BIE estimation method with Laplacian distribution(LBIE)is proposed,and several key issues are discussed,including the weight function of LBIE,determination of the candidates included based on the OIA test,and derivation of the variance of LBIE solutions for reliability evaluation.The results show that the proposed LBIE method has the positioning accuracy similar to the BIE using multivariate t-distribution(TBIE),and significantly outperforms the ILS-PAR and GBIE methods.In an urban expressway test with a Huawei Mate40 smartphone,the LBIE method has positioning errors of less than 0.5 m in three directions and obtains over 50%improvements compared to the ILS-PAR and GBIE methods.In an urban canyon test with a low-cost receiver STA8100 produced by STMicroelectronics,the positioning accuracy of LBIE in three directions is 0.112 m,0.107 m,and 0.252 m,respectively,with improvements of 17.6%,27.2%,and 26.1%compared to GBIE,and 23.3%,28.2%,and 30.6%compared to ILS-PAR.Moreover,its computational time increases by 30–40%compared to ILS-PAR and is approximately half of that using TBIE.
基金financial supports from the Austrialia Cooperative Research Centre for Spatial Information (CRCSI) Project (Grant No. P1.04)the Key Laboratory of Advanced Engineering Sur-veying of SBSM (Grant No. TJES0809)
文摘This paper presents the technical basis for wide area real time decimetre positioning services using multiple carrier signals transmitted by future GNSS such as modernized GPS and Compass systems. The first step is to form two ionosphere-reduced extra-widelanes (EWL) that have the minimal total noise levels in cycles, considering the effects of the ionospheric and tropospheric delays, orbital error, and phase noise terms in various observational environments. The proposed three carrier ambiguity resolution approach can determine the integer ambiguities of the selected EWL signals with geometry-free and geometry- based estimations respectively over the distances of typically hundreds of kilometres. With two ambiguity-fixed EWL signals, the kinematic positioning solutions can be achieved in decimetre level accuracy. A semi-simulation method is employed to generate three frequency Compass data to demonstrate the above expected performance for decimetre positioning services. Both theoretical and experimental results have demonstrated the overall 3D root mean square accuracy of better than 15 cm obtained through with a phase smoothing process over 120 epochs. The dominating error factor in this positioning result is the residual tropospheric biases, which would become less correlated as the baselines grow beyond hundreds of kilometres. With respect to dual-frequency based precise point positioning and wide area differential positioning solutions, a major advantage of using the third frequency signals is the convergence time being shorten from tens of minutes to a few minutes. In addition, due to the instant ambiguity resolution capability, phase breaks or cycle slips no longer affect the continuity of the solutions. This reliable decimetre positioning capability introduces a significant improvement to safety-of-life, liability-critical and professional applications.
文摘哨兵(Sentinel)-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为研究基于全球导航卫星系统多星座的低轨卫星精密定轨提供了契机。固定载波相位模糊度可提升低轨卫星的定轨精度,利用在轨实测数据研究GPS/Galileo双系统组合以及模糊度固定对低轨卫星运动学定轨精度的影响。分别采用欧洲定轨中心(Center for Orbit Determination in Europe,CODE)、法国国家空间研究中心(Centre National d’Etudes Spatiales,CNES)、德国地学研究中心(German Research Centre for Geosciences,GFZ)和中国武汉大学(Wuhan University,WHU)发布的观测值偏差及对应的精密星历和钟差产品开展单接收机模糊度固定。结果表明:GPS/Galileo双系统组合可明显改善定轨几何构型。双系统组合浮点解轨道三维精度优于30 mm,相对于GPS单系统提升超过20%。模糊度固定显著提升了运动学定轨精度,组合固定解轨道精度优于20 mm,相对于GPS提升30%。基于CODE、CNES和GFZ产品的GPS和Galileo单系统模糊度固定率分别优于93%和95%,WHU产品的Galileo固定率则偏低。利用卫星激光测距(satellite laser ranging,SLR)观测数据对运动学定轨结果进行检核,单系统固定解轨道SLR残差均方根误差(root mean square,RMS)为13~15 mm,双系统组合固定解RMS则达到12~14 mm,提升超过10%。
