基于双星定位的载人航天应急搜救可行性研究

在载人航天应急搜救中,及时获取目标的位置信息,并准确掌握搜救载体的动态信息至关重要。目前,目标位置信息的获取主要依赖地面测控系统提供,而搜救载体的位置信息则是基于美国全球定位系统（GPS）获取的。从简化信息传输环节、增加信息传输的可靠性和保障航天员安全出发,提出了基于我国“北斗一号”卫星导航定位系统构建的载人航天应急搜救体系,并论证了该方案的可行性。     

航天GPS接收机设计

航天GPS接收机为航天器提供航迹、姿态、时问和相对距离等导航信息，提高航天嚣运行的自主性。文中介绍了清华宇航中。航天GPS接收的硬件和软件设计，给出测试结果和分析。     

GPS定位系统在公路工程测量中的应用

一、概述 GPS全球定位系统（Global Positioning System）在公路测量工程中的应用，在最近的两年得到了迅速推广，这主要依赖于GPS系统可以向全球任何用户全天候地提供高精度的三维坐标、三维速度和时间信息等技术参数。下面简述GPS的组成及工作原理。     

GPS在物理大地测量中的应用及GPS边值问题

针对GPS技术逐步用于物理大地测量的现状，从物理大地测量的基本原理及方法入手，分析了GPS对传统物理大地测量理论及方法所产生的影响、GPS在解决物理大地测量中的一些难题所发挥的作用以及对物理大地测量的一些功能所造成的变化。重点讨论了物理大地测量边值问题的基本属性的改变、第二边值问题的应用、高程系统的确定、GPS边值问题的定义、特征及求解。最后，对GPS与物理大地测量进一步结合所面临的有关问题进行了简要论述。     

GPS在地形测量中的应用

一、概述 GPS全球定位系统由空间卫星群和地面监控系统两大部分组成，测量用户还应有卫星接收设备。 （1）空间卫星群：GPS的空间卫星群由24颗高约20万公里的GPS卫星群组成，并均匀分布在6个轨道面上，各平面之间交角为60°，轨道和地球赤道的倾角为55°，卫星的轨道运行周期为11小时58分，这样可以保证在任何时间和任何地点地平线以上可以接收4到11颗GPS卫星发送出的信号。[第一段]     

GPS监控系统以及GIS在监控系统中的应用

GPS的应用日益受到人们的重视，在由GPS和无线通讯网络所构成的GPS监控系统中，GIS在其中起的作用也越发显得重要。本文从GPS监控系统开发及推广应用的角度出发，介绍GPS监控系统构成及GIS在其中的开发应用和GPS监控系统应用中需要注意的问题。     

GPS在航空重力测量中的应用

航空重力测量系统是以飞机为载体测定近地重力场的一种快速手段，GPS技术在其中起到了十分关键的作用，本文探讨了GPS在航空重力测量中的作用，并分析了一些试验结果，给出了结论。     

GPS在"数字地球"中的应用

从“数字地球”工程的引入开始，通过介绍GPS在“数字地球”工程几个领域中的应用，说明了GPS不可替代的重要地位。     

Kriging方法在GPS水准拟合中的应用

鉴于GPS水准测量在实际工程中的广泛应用,传统的曲面拟合法不能满足大区域水准拟合的精度要求。本文探讨了Kriging方法在GPS水准拟合中的应用,通过距离分组,确定变异函数,并结合实测数据对本文方法进行了测试,同时与传统曲面拟合法进行了比较,验证了Kriging方法具有拟合精度高、适用复杂的山区等特点。     

GPS与GSM在定位业务中的应用

对全球定位系统GPS（Global Positioning System)全球移动网络GSM（Global System Mobile)及AGPS（辅助GPS）技术在GSM网络定位业务中的应用进行了介绍，并给出了定位业务的几个典型应用。     

“GPS原理及应用”课程教学实践与探讨

结合山东建筑大学地理信息系统专业“GPS原理及应用”课程教学的实践,从教学内容、课堂教学、实践教学等方面对该课程教学与实践进行了探讨。     

MATLAB在GPS高程拟合中的应用

测量工作中为了得到测区内所有GPS点的正常高,必须由一些已知点及其高程异常进行拟合以求取未知点的高程异常。通过对GPS高程拟合模型的介绍,并引入MATLAB解决GPS高程拟合问题,找到了一种较好解决这类问题的方法,从而使GPS高程拟合问题变的简单易行。     

GPS tomography in the polar cap: comparison with ionosondes and in situ spacecraft data

Tomographic 4D reconstructions of ionospheric anomalies appearing in the high-latitude polar cap region are compared with plasma density measurements by digital ionosonde located near the north magnetic pole at Eureka station and with in situ plasma measurements on-board DMSP spacecraft. The moderate magnetic storm of 14–17 October 2002 is taken as an example of a geomagnetic disturbance which generates large-scale ionospheric plasma anomalies at mid-latitudes and in the polar cap region. Comparison of the GPS tomographic reconstructions over Eureka station with the ionosonde measurements of the F layer peak densities indicates that the GPS tomography correctly predicts the time of arrival and passage of the ionospheric tongue of ionization over the magnetic pole area, although the tomographic technique appears to under-estimate the value of F peak plasma density. Comparison with the in situ plasma measurements by the DMSP SSIES instruments shows that the GPS tomography correctly reproduces the large-scale spatial structure of ionospheric anomalies over a wide range of latitudes from mid-latitudes to the high-latitude polar cap region, though the tomographic reconstructions tend to over-estimate the density of the topside ionosphere at 840 km DMSP orbit. This study is essential for understanding the quality and limitations of the tomographic reconstruction techniques, particularly in high-latitude regions where GPS TEC measurements and other ionospheric data sources are limited.     

附加约束法及其在GPS快速定位中的应用

针对在短时间内GPS观测方程的法方程容易形成病态的实际,探讨用附加约束条件来消除其病态性的方法,然后用LAMBDA方法确定其整周模糊度,实际实验证明,对于单频GPS接收机,利用连续几个历元数据,使用该技术即可正确确定整周模糊度,从而实现厘米级定位。     

The application of GPS precise point positioning technology in aerial triangulation

In traditional GPS-supported aerotriangulation, differential GPS (DGPS) positioning technology is used to determine the 3-dimensional coordinates of the perspective centers at exposure time with an accuracy of centimeter to decimeter level. This method can significantly reduce the number of ground control points (GCPs). However, the establishment of GPS reference stations for DGPS positioning is not only labor-intensive and costly, but also increases the implementation difficulty of aerial photography. This paper proposes aerial triangulation supported with GPS precise point positioning (PPP) as a way to avoid the use of the GPS reference stations and simplify the work of aerial photography.Firstly, we present the algorithm for GPS PPP in aerial triangulation applications. Secondly, the error law of the coordinate of perspective centers determined using GPS PPP is analyzed. Thirdly, based on GPS PPP and aerial triangulation software self-developed by the authors, four sets of actual aerial images taken from surveying and mapping projects, different in both terrain and photographic scale, are given as experimental models. The four sets of actual data were taken over a flat region at a scale of 1:2500, a mountainous region at a scale of 1:3000, a high mountainous region at a scale of 1:32000 and an upland region at a scale of 1:60000 respectively. In these experiments, the GPS PPP results were compared with results obtained through DGPS positioning and traditional bundle block adjustment. In this way, the empirical positioning accuracy of GPS PPP in aerial triangulation can be estimated. Finally, the results of bundle block adjustment with airborne GPS controls from GPS PPP are analyzed in detail.The empirical results show that GPS PPP applied in aerial triangulation has a systematic error of half-meter level and a stochastic error within a few decimeters. However, if a suitable adjustment solution is adopted, the systematic error can be eliminated in GPS-supported bundle block adjustment. When four full GCPs are emplaced in the corners of the adjustment block, then the systematic error is compensated using a set of independent unknown parameters for each strip, the final result of the bundle block adjustment with airborne GPS controls from PPP is the same as that of bundle block adjustment with airborne GPS controls from DGPS. Although the accuracy of the former is a little lower than that of traditional bundle block adjustment with dense GCPs, it can still satisfy the accuracy requirement of photogrammetric point determination for topographic mapping at many scales.     

基于IGS超快速星历的高精度实时GPS测量

IGS的几种星历产品中,精密星历精度虽然高,但不能实时获得,并且它是影响高精度实时测量应用的主要因素。讨论几种星历产品数值上的差异,在实际计算中使用超快预报星历替代精密星历,并比较它们基线解算结果和天顶延迟解算结果。结果证明：两种星历计算的基线差别非常小,因此,在高精度GPS数据处理中可以直接使用超快预报星历,得到高精度的实时坐标。同样可以应用在GPS气象中,用超快事后星历实现对流层实时监测。