【作者】 史峰；

【导师】 姚连璧；

【作者基本信息】 同济大学 ， 地图制图学与地理信息工程， 2007， 硕士

【摘要】 自上世纪80年代初GPS系统投入运行以来，伴随着电子、计算机以及通讯技术的不断发展，GPS的应用领域不断拓广，从早期的军事、航海、测绘、地质等专业领域，逐渐向基于位置服务(LBS)、交通调度管理、土地资源调查、物流等与人们日常生活密切相关的领域发展。但由于GPS定位受到卫星分布、信号遮挡、大气延迟、多径效应等各种复杂的因素的影响，其定位的精度及完整性并不能满足很多应用要求。对于GPS移动定位用户而言，虚拟参考站技术和卫星增强系统是应用价值较高的两种改善GPS定位精度和完整性的方式。虚拟参考站技术(Virtual Reference Station，VRS)是在持续运行参考站系统(CORS)基础上发展起来的一种实时动态定位系统。VRS技术通过Internet实时的向其流动站用户播发根据其多基站网络计算得出GPS差分改正信息，这些差分信息是针对流动站当前位置的改正信息，这样就如同在流动站的附近虚拟出了一个新的基准站，流动站与基准站的距离大大缩短，定位的精度和稳定性都得到提高。卫星增强系统(Satellite Based Augmentation Systems，SBAS)是一种基于卫星的GPS增强系统，SBAS通过增加额外卫星的方式为移动用户提供差分改正数据以及更多的可用的定位卫星。本论文研究的目的就是结合VRS以及SBAS技术，探讨如何在PDA平台上为GPS移动定位用户提供可靠、稳定和较高精度的定位服务。论文首先回顾了GPS定位增强方式的发展，并结合移动定位的特点对各种增强方式进行了讨论和比较。接着对VRS和SBAS的基本原理、工作方法以及移动定位的误差源等进行了分析。在此基础上，论文在Windows Mobile5.0平台的PDA上利用GPS中间件技术和蓝牙GPS(SiRFIII芯片)实现了基于SBAS的GPS移动定位软件。在研究RTCM数据格式、NTRIP通讯协议以及Windows Mobile5.0 Internet通讯基础上，利用Ashtech Z-Xtreme GPS接收机开发了RTK移动定位软件。最后分别使用两套系统在同济大学校内控制点进行了定位试验，对系统的定位精度及可靠性进行了分析。更多还原

【Abstract】 Since the fully operation of GPS system in 1990s, with the development ofelectronics, computer and communication technologies, GPS’s application fieldsexpanded from professional ones such as military, marine navigation, survey andgeology to some daily applications such as LBS (Location Based Service), trafficcontrol, land resource survey and logistics etc. But due to the complex influencefactors of distribution of GPS satellites, signal obstruction, atmospheric delay andmultipath etc, the accuracy and integrity of GPS positioning is insufficient for manyrequirements. For the mobile user of GPS positioning, VRS (Virtual ReferenceStation) and SBAS (Satellite Base Augmentation System) are two useful techniquesto improve the positioning quality.VRS is a kind of real time kinematic positioning technique developed fromCORS (Continuously Operating Reference Stations).VRS system continuouslycomputing differential corrections based on the data collected from multi-referencestation network and send these corrections to rover users under certain protocol viaInternet. Since these corrections are provided according to the current positions ofrover users, i.e. the ’Virtual’ reference station is installed just near the rover user,the degradation of accuracy caused by the less correlation between rover-referencestations are substantially avoided, and integrity and accuracy are improved as a result.SBAS is a kind of satellite base GPS augmentation technique. Mobile users canreceive differential corrections from extra GEO satellites, and these satellitesthem-selves also transmit ranging signals on the same frequency as GPS L1, thusboth the accuracy and integrity will be enhanced.The aim of this dissertation is to provide a reliable, stable and high precisionmobile positioning service for various mobile applications by the combination ofVRS and SBAS. Firstly, several kinds of GPS augmentation techniques are reviewed,and the characteristics of these techniques are discussed according to the special needof mobile positioning. Then the basic concepts of VRS and SBAS are introduced, as well as the operation model and systematic error source. Based on these theories, aSBAS GPS mobile positioning system is developed utilizing the GPS IntermediateDriver and a SiRFIII chipset on a Widows Mobile 5.0 platform PDA. Based onresearches of format of RTCM data, NTRIP protocol and Windows Mobile 5.0Internet communication, a high precision RTK mobile positioning system isdeveloped on PDA with Ashtech Z-Xtreme receiver. In the finality, the precision andintegrities of the two systems are analyzed by the data collected from a field testconducted in the campus of Tongji University.更多还原