We present two efficient approaches,namely the epoch-differenced(ED) and satellite-and epoch-differenced(SDED) approaches,for the estimation of IFCBs of the two Block IIF satellites.For the analysis,data from 18 stati...We present two efficient approaches,namely the epoch-differenced(ED) and satellite-and epoch-differenced(SDED) approaches,for the estimation of IFCBs of the two Block IIF satellites.For the analysis,data from 18 stations from the IGS network spanning 96 d is processed.Results show that the IFCBs of PRN25 and PRN01 exhibit periodical signal of one orbit revolution with a magnitude up to 18 cm.The periodical variation of the IFCBs is modeled by a sinusoidal function of the included angle between the sun,earth and the satellite.The presented model enables a consistent use of L1/L2 clock products in L1/L5-based positioning.The algorithm is incorporated into the MGPSS software at SHAO(Shanghai Astronomical Observatory,Chinese Academy of Sciences) and is used to monitor the IFCB variation in near real-time.展开更多
Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. I...Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring （RAIM） method earmot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias （RCB） is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites.展开更多
A new prediction method based on the nonlinear autoregressive model is proposed to improve the accuracy of medium-term and long-term predictions of Satellite Clock Bias(SCB).Forecast experiments for three time periods...A new prediction method based on the nonlinear autoregressive model is proposed to improve the accuracy of medium-term and long-term predictions of Satellite Clock Bias(SCB).Forecast experiments for three time periods were implemented based on the precision SCB published on the International GNSS Server(IGS)server.The results show that the medium-term and long-term prediction accuracy of the proposed approach is significantly better compared to other traditional models,with the training time being much shorter than the wavelet neural network model.展开更多
针对牵引式欺骗对授时接收机危害性强且难以检测的问题,基于授时欺骗的实施原理分析了授时解的变化规律,利用欺骗实施后钟差必然累积异常的特点,提出了一种钟差构造检验统计量的授时欺骗检测与识别方法。分析了该方法的检测性能,并通过...针对牵引式欺骗对授时接收机危害性强且难以检测的问题,基于授时欺骗的实施原理分析了授时解的变化规律,利用欺骗实施后钟差必然累积异常的特点,提出了一种钟差构造检验统计量的授时欺骗检测与识别方法。分析了该方法的检测性能,并通过蒙特卡罗仿真验证了理论的正确性。最后使用软件接收机对TEXBAT(Texas spoofing test battery)授时欺骗场景数据进行测试验证了该方法的有效性。由于不需要接收机添加额外的硬件且在无位置信息辅助的情况下该算法依然能够检测欺骗,因此对全球卫星导航系统授时安全具有较高的应用价值。展开更多
Over the past years the International Global Navigation Satellite System(GNSS)Monitoring and Assessment System(iGMAS)Wuhan Innovation Application Center(IAC)dedicated to exploring the potential of multi-GNSS signals a...Over the past years the International Global Navigation Satellite System(GNSS)Monitoring and Assessment System(iGMAS)Wuhan Innovation Application Center(IAC)dedicated to exploring the potential of multi-GNSS signals and providing a set of products and services.This contribution summarizes the strategies,achievements,and innovations of multi-GNSS orbit/clock/bias determination in iGMAS Wuhan IAC.Both the precise products and Real-Time Services(RTS)are evaluated and discussed.The precise orbit and clock products have comparable accuracy with the precise products of the International GNSS Service(IGS)and iGMAS.The multi-frequency code and phase bias products for Global Positioning System(GPS),BeiDou Navigation Satellite System(BDS),Galileo navigation satellite system(Galileo),and GLObal NAvigation Satellite System(GLONASS)are provided to support multi-GNSS and multi-frequency Precise Point Positioning(PPP)Ambiguity Resolution(AR).Compared with dual-frequency PPP AR,the time to first fix of triple-frequency solution is improved by 30%.For RTS,the proposed orbit prediction strategy improves the three dimensional accuracy of predicted orbit by 1 cm.The multi-thread strategy and high-performance matrix library are employed to accelerate the real-time orbit and clock determination.The results with respect to the IGS precise products show the high accuracy of RTS orbits and clocks,4–9 cm and 0.1–0.2 ns,respectively.Using real-time satellite corrections,real-time PPP solutions achieve satisfactory performance with horizontal and vertical positioning errors within 2 and 4 cm,respectively,and convergence time of 16.97 min.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41204034,41174023 and 11173049)the Opening Project of Shanghai Key Laboratory of Space Navigation and Position Techniques (Grant No. Y224 353002)
文摘We present two efficient approaches,namely the epoch-differenced(ED) and satellite-and epoch-differenced(SDED) approaches,for the estimation of IFCBs of the two Block IIF satellites.For the analysis,data from 18 stations from the IGS network spanning 96 d is processed.Results show that the IFCBs of PRN25 and PRN01 exhibit periodical signal of one orbit revolution with a magnitude up to 18 cm.The periodical variation of the IFCBs is modeled by a sinusoidal function of the included angle between the sun,earth and the satellite.The presented model enables a consistent use of L1/L2 clock products in L1/L5-based positioning.The algorithm is incorporated into the MGPSS software at SHAO(Shanghai Astronomical Observatory,Chinese Academy of Sciences) and is used to monitor the IFCB variation in near real-time.
基金Project(20090580013) supported by the Aeronautic Science Foundation of ChinaProject(ZYGX2010J119) supported by the Fundamental Research Funds for the Central Universities,China
文摘Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring （RAIM） method earmot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias （RCB） is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites.
基金2022 Basic Scientific Research Project supported by Liaoning Provincial Education Department(No.LJKMZ20221686)。
文摘A new prediction method based on the nonlinear autoregressive model is proposed to improve the accuracy of medium-term and long-term predictions of Satellite Clock Bias(SCB).Forecast experiments for three time periods were implemented based on the precision SCB published on the International GNSS Server(IGS)server.The results show that the medium-term and long-term prediction accuracy of the proposed approach is significantly better compared to other traditional models,with the training time being much shorter than the wavelet neural network model.
文摘针对牵引式欺骗对授时接收机危害性强且难以检测的问题,基于授时欺骗的实施原理分析了授时解的变化规律,利用欺骗实施后钟差必然累积异常的特点,提出了一种钟差构造检验统计量的授时欺骗检测与识别方法。分析了该方法的检测性能,并通过蒙特卡罗仿真验证了理论的正确性。最后使用软件接收机对TEXBAT(Texas spoofing test battery)授时欺骗场景数据进行测试验证了该方法的有效性。由于不需要接收机添加额外的硬件且在无位置信息辅助的情况下该算法依然能够检测欺骗,因此对全球卫星导航系统授时安全具有较高的应用价值。
基金National Natural Science Foundation of China(No.41974027)National Key Research and Development Program of China(2021YFB2501102)Sino-German mobility programme(Grant No.M-0054).
文摘Over the past years the International Global Navigation Satellite System(GNSS)Monitoring and Assessment System(iGMAS)Wuhan Innovation Application Center(IAC)dedicated to exploring the potential of multi-GNSS signals and providing a set of products and services.This contribution summarizes the strategies,achievements,and innovations of multi-GNSS orbit/clock/bias determination in iGMAS Wuhan IAC.Both the precise products and Real-Time Services(RTS)are evaluated and discussed.The precise orbit and clock products have comparable accuracy with the precise products of the International GNSS Service(IGS)and iGMAS.The multi-frequency code and phase bias products for Global Positioning System(GPS),BeiDou Navigation Satellite System(BDS),Galileo navigation satellite system(Galileo),and GLObal NAvigation Satellite System(GLONASS)are provided to support multi-GNSS and multi-frequency Precise Point Positioning(PPP)Ambiguity Resolution(AR).Compared with dual-frequency PPP AR,the time to first fix of triple-frequency solution is improved by 30%.For RTS,the proposed orbit prediction strategy improves the three dimensional accuracy of predicted orbit by 1 cm.The multi-thread strategy and high-performance matrix library are employed to accelerate the real-time orbit and clock determination.The results with respect to the IGS precise products show the high accuracy of RTS orbits and clocks,4–9 cm and 0.1–0.2 ns,respectively.Using real-time satellite corrections,real-time PPP solutions achieve satisfactory performance with horizontal and vertical positioning errors within 2 and 4 cm,respectively,and convergence time of 16.97 min.
