The maritime navigation accuracy requirements for radionavigation systems such as GPS are specified by the International Maritime Organization (IMO). Maritime navigation usually consists of three major phases identifi...The maritime navigation accuracy requirements for radionavigation systems such as GPS are specified by the International Maritime Organization (IMO). Maritime navigation usually consists of three major phases identified as Ocean/Coastal/Port approach/Inland waterway, in port navigation and automatic docking with an accuracy requirement that ranges from 10 m to 0.1 m. With the advancement in autonomous GPS positioning techniques such as Precise Point Positioning (PPP) and with the advent of the new IGS-Real-Time-Service (RTS), it is necessary to assess the possibility of a wider role of the PPP-based positioning technique in maritime applications. This paper investigates the performance of an autonomous real-time PPP-positioning solution by using the IGS- RTS service for maritime applications that require an accurate positioning system. To examine the performance of the real-time IGS-RTS PPP-based technique for maritime applications, kinematic data from a dual frequency GPS receiver is investigated. It is shown that the real-time IGS-RTS PPP-based GPS positioning technique fulfills IMO requirements for maritime applications with an accuracy requirement ranges from 10 m for Ocean/Coastal/Port approach/Inland waterways navigation to 1.0 m for in port navigation but cannot fulfill the automatic docking application with an accuracy requirement of 0.10 m. To further investigate the real-time PPP-based GPS positioning technique, a comparison is made between the real-time IGS-RTS PPP-based positioning technique and the real-time PPP-based positioning by using the predicted part of the IGS Ultra-Rapid products and the real-time GPS positioning technique with the Wide Area Differential GPS service (WADGPS). It is shown that the IGS-RTS PPP-based positioning technique is superior to the IGS-Ultra-Rapid PPP-based and WADGPS-based positioning techniques.展开更多
We elaborate an error budget for the long-term accuracy of IGS(International Global Navigation Satellite System Service) polar motion estimates, concluding that it is probably about 25-30 μas(1-sigma)overall, alt...We elaborate an error budget for the long-term accuracy of IGS(International Global Navigation Satellite System Service) polar motion estimates, concluding that it is probably about 25-30 μas(1-sigma)overall, although it is not possible to quantify possible contributions(mainly annual) that might transfer directly from aliases of subdaily rotational tide errors. The leading sources are biases arising from the need to align daily, observed terrestrial frames, within which the pole coordinates are expressed and which are continuously deforming, to the secular, linear international reference frame. Such biases are largest over spans longer than about a year. Thanks to the very large number of IGS tracking stations, the formal covariance errors are much smaller,around 5 to 10 μas. Large networks also permit the systematic frame-related errors to be more effectively minimized but not eliminated. A number of periodic errors probably also influence polar motion results, mainly at annual, GPS(Global Positioning System) draconitic, and fortnightly periods, but their impact on the overall error budget is unlikely to be significant except possibly for annual tidal aliases. Nevertheless, caution should be exercised in interpreting geophysical excitations near any of the suspect periods.展开更多
当前,在低轨导航增强、对地观测和科学应用等领域,低轨卫星对轨道参数的精度和实时性提出了更高的要求。利用国际GNSS服务组织实时服务(international global navigation satellite system service real-time service,IGS-RTS)播发的GP...当前,在低轨导航增强、对地观测和科学应用等领域,低轨卫星对轨道参数的精度和实时性提出了更高的要求。利用国际GNSS服务组织实时服务(international global navigation satellite system service real-time service,IGS-RTS)播发的GPS卫星轨道与钟差改正数,针对极区实时改正数接收中断情况下实现厘米级星载GPS实时定轨的关键问题开展研究。首先分析了实时改正数及其短时外推引起的星历综合误差的变化特性;然后以此为依据,在星载GPS实时精密定轨数学模型中构建分段随机游走的伪模糊度参数随机模型,以减小星历综合误差对实时精密定轨的影响,从而实现厘米级精度的实时定轨。采用自主研制的实时精密定轨软件SATODS,使用GPS广播星历与CLK93实时产品,对为期一周的重力场恢复和气候实验(gravity recovery and climate experiment,GRACE)C卫星的GPS双频实测数据模拟在轨实时精密定轨处理。实验结果表明,在考虑极区改正数接收中断的情况下,所提实时精密定轨方法可以达到7.04 cm的位置精度以及0.20 mm/s的速度精度,所提方法具有可行性和有效性。展开更多
以IGS(international GPS service)发布的电离层TEC(total electron content)资料为样本,用时间序列模型对全球的电离层总电子含量进行了预报。在时间序列预报模型中,不同的定阶方法导致不同的预报结果;实践证明本文使用的BIC定阶准则...以IGS(international GPS service)发布的电离层TEC(total electron content)资料为样本,用时间序列模型对全球的电离层总电子含量进行了预报。在时间序列预报模型中,不同的定阶方法导致不同的预报结果;实践证明本文使用的BIC定阶准则较好地实现了电离层总电子含量的预报。结果表明:对10d左右的预报时间段,时间序列模型的TEC计算结果相对精度高,预报相对精度优于60%的网格点数在总网格点数中所占百分比可达90%以上。展开更多
文摘The maritime navigation accuracy requirements for radionavigation systems such as GPS are specified by the International Maritime Organization (IMO). Maritime navigation usually consists of three major phases identified as Ocean/Coastal/Port approach/Inland waterway, in port navigation and automatic docking with an accuracy requirement that ranges from 10 m to 0.1 m. With the advancement in autonomous GPS positioning techniques such as Precise Point Positioning (PPP) and with the advent of the new IGS-Real-Time-Service (RTS), it is necessary to assess the possibility of a wider role of the PPP-based positioning technique in maritime applications. This paper investigates the performance of an autonomous real-time PPP-positioning solution by using the IGS- RTS service for maritime applications that require an accurate positioning system. To examine the performance of the real-time IGS-RTS PPP-based technique for maritime applications, kinematic data from a dual frequency GPS receiver is investigated. It is shown that the real-time IGS-RTS PPP-based GPS positioning technique fulfills IMO requirements for maritime applications with an accuracy requirement ranges from 10 m for Ocean/Coastal/Port approach/Inland waterways navigation to 1.0 m for in port navigation but cannot fulfill the automatic docking application with an accuracy requirement of 0.10 m. To further investigate the real-time PPP-based GPS positioning technique, a comparison is made between the real-time IGS-RTS PPP-based positioning technique and the real-time PPP-based positioning by using the predicted part of the IGS Ultra-Rapid products and the real-time GPS positioning technique with the Wide Area Differential GPS service (WADGPS). It is shown that the IGS-RTS PPP-based positioning technique is superior to the IGS-Ultra-Rapid PPP-based and WADGPS-based positioning techniques.
文摘We elaborate an error budget for the long-term accuracy of IGS(International Global Navigation Satellite System Service) polar motion estimates, concluding that it is probably about 25-30 μas(1-sigma)overall, although it is not possible to quantify possible contributions(mainly annual) that might transfer directly from aliases of subdaily rotational tide errors. The leading sources are biases arising from the need to align daily, observed terrestrial frames, within which the pole coordinates are expressed and which are continuously deforming, to the secular, linear international reference frame. Such biases are largest over spans longer than about a year. Thanks to the very large number of IGS tracking stations, the formal covariance errors are much smaller,around 5 to 10 μas. Large networks also permit the systematic frame-related errors to be more effectively minimized but not eliminated. A number of periodic errors probably also influence polar motion results, mainly at annual, GPS(Global Positioning System) draconitic, and fortnightly periods, but their impact on the overall error budget is unlikely to be significant except possibly for annual tidal aliases. Nevertheless, caution should be exercised in interpreting geophysical excitations near any of the suspect periods.
文摘当前,在低轨导航增强、对地观测和科学应用等领域,低轨卫星对轨道参数的精度和实时性提出了更高的要求。利用国际GNSS服务组织实时服务(international global navigation satellite system service real-time service,IGS-RTS)播发的GPS卫星轨道与钟差改正数,针对极区实时改正数接收中断情况下实现厘米级星载GPS实时定轨的关键问题开展研究。首先分析了实时改正数及其短时外推引起的星历综合误差的变化特性;然后以此为依据,在星载GPS实时精密定轨数学模型中构建分段随机游走的伪模糊度参数随机模型,以减小星历综合误差对实时精密定轨的影响,从而实现厘米级精度的实时定轨。采用自主研制的实时精密定轨软件SATODS,使用GPS广播星历与CLK93实时产品,对为期一周的重力场恢复和气候实验(gravity recovery and climate experiment,GRACE)C卫星的GPS双频实测数据模拟在轨实时精密定轨处理。实验结果表明,在考虑极区改正数接收中断的情况下,所提实时精密定轨方法可以达到7.04 cm的位置精度以及0.20 mm/s的速度精度,所提方法具有可行性和有效性。
文摘以IGS(international GPS service)发布的电离层TEC(total electron content)资料为样本,用时间序列模型对全球的电离层总电子含量进行了预报。在时间序列预报模型中,不同的定阶方法导致不同的预报结果;实践证明本文使用的BIC定阶准则较好地实现了电离层总电子含量的预报。结果表明:对10d左右的预报时间段,时间序列模型的TEC计算结果相对精度高,预报相对精度优于60%的网格点数在总网格点数中所占百分比可达90%以上。
文摘为了完善当前智能交通的不足,设计了一种垃圾车的监控装置。该装置通过全球定位系统(Global Positioning System,GPS)模块获取定位信息后,将数据通过串口发送给STM32进行压缩编码和数据封装处理,再发送给通用分组无线服务(General Packet Radio Service,GPRS)模块通过传输控制协议/网际协议(Transmission Control Protocol/Internet Protocol,TCP/IP)与服务器建立连接将定位信息发送到服务器,配合互联网软件,监控城市垃圾运输车行为与位置。测试结果表明,设计的监控装置能实现设计目标,具有较强的实用性。