基于VRS的GPS测量误差分析

系统误差包括卫星轨道误差、卫星钟差、接收机钟差及大气折射误差等。是GPS测量的主要误差源。但系统误差通常可以采用适当的方法来减弱或消除,如建立误差改正模型对观测值进行改正,或选择良好的观测条件,采用适当地观测方法,进行线性差分等.本文介绍了基于VRS的GPS测量要解决的一个主要问题即在系统运行中产生的各种误差进行改正,使之减小或者消除。并就影响VRS精度的各种误差予以分析     

南京市首级高程控制网的建立及跨江水准的研究

本文首先介绍了南京市首级高程控制网的概况,接着重点讨论了跨江水准测量方法的选择,并全面分析了测距三角高程法影响精度的三个因素,结合南京市首级高程控制网全面介绍了数据处理的有关问题。     

单频GPS接收机天线扼流圈的研制与测试

讨论了多路径效应对GPS共视比对的影响及削弱其影响的方法。结合综合原子时项目的需求,研制了适用于单频GPS接收机的天线扼流圈,并用零基线比对方法进行了测试。结果表明,研制的天线扼流圈可有效地削弱多路径效应的影响,并可明显地改善单频GPS接收机NTSCGPS-1的抗干扰能力。     

Groundwater study using remote sensing and geographic information systems (GIS) in the central highlands of Eritrea

Remote sensing, evaluation of digital elevation models (DEM), geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Eritrea. Remote sensing data were interpreted to produce lithological and lineament maps. DEM was used for lineament and geomorphologic mapping. Field studies permitted the study of structures and correlated them with lineament interpretations. Hydrogeological setting of springs and wells were investigated in the field, from well logs and pumping test data. All thematic layers were integrated and analysed in a GIS. Results show that groundwater occurrence is controlled by lithology, structures and landforms. Highest yields occur in basaltic rocks and are due to primary and secondary porosities. High yielding wells and springs are often related to large lineaments, lineament intersections and corresponding structural features. In metamorphic and igneous intrusive rocks with rugged landforms, groundwater occurs mainly in drainage channels with valley fill deposits. Zones of very good groundwater potential are characteristic for basaltic layers overlying lateritized crystalline rocks, flat topography with dense lineaments and structurally controlled drainage channels with valley fill deposits. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan.The online version of the original article can be found at     

GPS高程拟合的方式及可靠性分析

在范围不大的区域中，高程异常具有一定的几何相关性，GPS高程拟合就是利用这一原理，求解正常高。在解析法求解过程中，首先用最小二乘法确定拟合数学模型的系数，在此基础上计算出待测点的高程异常值。通过实例验证：GPS高程拟合的精度主要取决于GPS大地高的精度、重合点正常高的精度、重合点的分布及拟模型的选择。一般在重合点数量充足且分布均匀的情况下，GPS高程拟合的精度可达到四等水准网的精度要求。     

三种高程传递方法的精度分析

通过试验对悬挂钢尺、GPS测高和全站仪垂直测高三种高程传递方法进行了理论分析与精度比较,并讨论了各种方法在实际应用中的优点与局限性。     

RTK航道疏浚应用及工程坐标转换参数的获取

本文结合实时差分(RealTimeDifference)GPS定位技术在某海港航道疏浚工程中的应用,介绍了GPS导航定位测量中WGS-84坐标与工程坐标系的转换方法及应用。     

基于GIS和GPS的中铁快运信息监控系统

基于地理信息系统、卫星定位系统、无线接入技术、大型数据库以及网络等技术,建立了一个中铁快运信息监控系统,实现了对快运车辆、人员的监控调度管理及车辆人员与监控中心的互动,形成了中心监控、网络调度和计算机管理的先进中铁快运模式。