The International GPS Service tracking network: Enabling diverse studies and projects through international cooperation

The International GPS Service (IGS), formulated beginning in 1989 and formalized in 1994, was founded on the collaborative operation of approximately 30 permanent GPS stations to benefit global geodynamics. The same cooperative principles, today applied to a network of over 300 stations, still serve to maximize global benefit without unnecessary duplication of investment in global infrastructure. The scope of applications of the dataset has grown to include atmospheric, oceanographic, subdaily, and low-earth orbiter activities through working groups and pilot projects fostered within the IGS in the now traditional IGS spirit of collaboration. These activities and the IGS infrastructure are viewed as critical elements to the Global Geodetic Observing System. This presentation will review the present nature of the IGS tracking network and its ability to support new applications.     

GPS/Doppler导航随机模型的移动窗口实时估计算法

引进时间遗忘因子和观测冗余度因子,有效地平衡移动窗口内不同时刻的观测数据及其冗余情况对单位权方差估值的贡献,改进单位权方差的移动开窗实时估计算法.采用载噪比模型确定观测权阵,等价权抗差估计方法处理粗差.实测车载GPS/Doppler数据的处理结果表明:采用本文算法显著提高GPS/Doppler的导航精度与可靠性.     

GPS在桥梁跨河水准测量中的应用研究

传统的跨河水准测量方法以几何光学观测为基础,受距离和气候条件的影响显著,工作效率较低.GPS技术所具有的三维定位功能,以其快速、全天候测量的优点,为跨河高程测量提供了一条新的途径.本文针对桥梁工程特点,探讨了GPS跨河水准测量的基本原理和方法,采用线性拟合模型推求跨河点之间的高程异常差,再结合GPS大地高即可求得跨河高差.在安庆长江铁路大桥精密控制网测量中,进行了二等GPS跨河水准测量试验,采用测距三角高程法进行验证,较差为4.7mm.     

Validation of MODIS integrated water vapor product against reference GPS data at the Iberian Peninsula

In this work, the water vapor product from MODIS (MODerate-resolution Imaging Spectroradiometer) instrument, on-board Aqua and Terra satellites, is compared against GPS water vapor data from 21 stations in the Iberian Peninsula as reference. GPS water vapor data is obtained from ground-based receiver stations which measure the delay caused by water vapor in the GPS microwave signals. The study period extends from 2007 until 2012. Regression analysis in every GPS station show that MODIS overestimates low integrated water vapor (IWV) data and tends to underestimate high IWV data. R² shows a fair agreement, between 0.38 and 0.71. Inter-quartile range (IQR) in every station is around 30–45%. The dependence on several parameters was also analyzed. IWV dependence showed that low IWV are highly overestimated by MODIS, with high IQR (low precision), sharply decreasing as IWV increases. Regarding dependence on solar zenith angle (SZA), performance of MODIS IWV data decreases between 50° and 90°, while night-time MODIS data (infrared) are quite stable. The seasonal cycles of IWV and SZA cause a seasonal dependence on MODIS performance. In summer and winter, MODIS IWV tends to overestimate the reference IWV value, while in spring and autumn the tendency is to underestimate. Low IWV from coastal stations is highly overestimated (∼60%) and quite imprecise (IQR around 60%). On the contrary, high IWV data show very little dependence along seasons. Cloud-fraction (CF) dependence was also studied, showing that clouds display a negligible impact on IWV over/underestimation. However, IQR increases with CF, except in night-time satellite values, which are quite stable.     

基于MapX的车辆管理系统的开发与研究

根据某省交通部门对车辆查询和管理服务的实际需求,在GIS与GPS的理论基础上,采用具有强大地图分析功能的MapX和组件技术建立了一个Client／Server模式的GIS与GPS技术相结合的车辆管理系统。简要介绍了该系统的功能和体系结构,并详细讨论了系统实现的关键技术和方法,文章最后对未来的发展趋势进行了分析展望。     

机载GPS精密单点定位性能分析

利用地面多基站RTK测量结果和精密单点定位（PPP）测量结果,分析了机载条件下PPP定位、测速性能指标.实验结果表明：机载GPS精密单点定位绝对定位精度在位置、速度上可分别达到0.182 3m和0.024 6m/s,相对定位精度在位置、速度上可分别达到0.1450m和0.024 9m/s.     

基于GPS数据的CHAMP卫星简化动力法轨道确定

利用CHAMP卫星星载GPS实测数据,通过非差简化动力学定轨的方法,计算了CHAMP卫星2008年3月3日～10日的轨道,并以GFZ的快速轨道作为参考标准,评价了本文简化动力法轨道精度.结果表明,CHAMP卫星非差简化动力学轨道1D位置精度可达到7cm,1D的速度精度可达到0.1mm/s.     

广域差分GPS系统PNP-20的接收机及配套软件的研制与应用

论述了局域差分GPS技术受到的限制和广域差分GPS的原理及技术特点,介绍了PNP20广域差分系统 工作原理,并详细叙述其主要的软、硬件的特点和各种功能,分析了该系统的各种检测数据,最后对这套系统的 应用前景和主要优、缺点进行了评述。     

新型GPS控制网布设及应用

设计出一种新型GPS控制网,通过与其他类型控制网进行比较分析,获得该新型GPS网的一些特点,并将该新型GPS控制网应用于工程实际中,实践表明:该新型GPS网,无论平面精度还是高程精度都高于设计精度,能够满足多种工程测量需要,值得借鉴。     

GPS／GLoNASS组合定位的抗差Helmert方差分量估计模型

GPS和GLONASS存在系统差异,组合定位时,采用Helmert方差分量估计可得到更加准确的结果。但GNSS观测值常受到衍射信号和多路径效应的影响,使观测值存有粗差,从而导致Helmert方差分量估计的失真。为此,将抗差Helmert方差分量估计应用于GPS／GLONASS组合单点定位,实验结果表明：抗差Helmert方差分量估计可以有效地抑制组合系统粗差观测值的影响。