全球导航卫星系统的新进展

Recent progress in global navigation of satellite system

本文综合介绍了于 2 0 0 4年 9月 2 1日至 2 4日在美国加州举行的“全球导航卫星系统” 2 0 0 4年年会(GNSS2 0 0 4 )会议的主要议题 ,并对其中我们可能关切的方面进行了重点介绍。①美国的GPS连续运行站网(CORS)。CORS由美国大地测量局 (NGS)主持运行。用户可以通过NGS网络 ,获得用户的GPS待定点相邻的CORS站 (三个以上 )的GPS相应载波相位和码距 ,以支持用户的GPS准实时或后处理定位。NGS也可以为用户通过网络提供GPS定位计算服务 ,这一服务可以在用户提供待定点的观测资料后的几个小时内完成 ,称为NGS的在线GPS定位服务。CORS目前在美国已有 5 0 0余个站。②GPS系统的进展。GPSⅡR型卫星从体形和功能方面都比较优秀 ,使GPS卫星在轨的位置误差显著降低 ,测距精度提高近一倍 ,目前GPSⅡR型卫星截止至 2 0 0 4年 1月 1日时有 9颗在轨。③利用L1 ,L2频道的GPS空基增强系统 (WAAS)。在美国大部分地区WAAS系统的水平精度可达 1～ 2m ,垂直精度可达 2～ 3m。④GPS信号的重构。美国已发展了一种高度逼真的和适应各种情况的虚拟GPS信号系统 ,这种虚拟发射装置可以是陆基的 ,空基的 ,或者星基的。GPS接收机可以利用这一虚拟的GPS信号进行精密定位。⑤Galileo卫星导航系统运行的准备工作。欧洲空间局已经重新和?

Global Navigation Satellite System 2004 Annual Symposium (ION GNSS 2004) was held in Long Beach CA,USA,Sept 21-24,by Institute of Navigation.The main topics in the GNSS 2004 are as follows.①Continuously operating reference stations (CORS).CORS is run by National Geodetic Survey (NGS),an office of National Oceanic and Atmospheric Administration (NOAA).CORS can provide GPS carrier phase and code range to the costumers in support of 3D positioning activities throughout the USA.CORS enables positioning accuracies that approach a few centimeters relative accuracy for a GPS baseline,both in horizontally and vertically.GPS user in USA may submit their static GPS data to NGS via the Web,and then the each summated data file will be processed with respect to three CORS sites,and the GPS user receives the computed position via email.Now there are more than 500 GPS CORS sites in USA.②Progress in GPS.GPSⅡR type satellite is better both in its shape and function.It reduces the errors obviously in its orbit position and the distance measurement.There are 9 GPS II R type satellites on the GPS orbit till Jan.01,2004.③Space based GPS wide area augmentation system (WAAS).The horizontal and vertical accuracies of the GPS positioning,by using of WAAS L1 and L2 band in USA,has reached 1～2m and 2～3m level respectively.④Reconstruction of GPS signal.A artificial or fictitious GPS signal system with high fidelity has been developed in USA.The fictitious signal radiation emission equipment can land base,space base or air base.GPS receiver can use the fictitious GPS signal to conduct precise positioning.⑤The preparation for Galileo system.The orbit height,constitution of signal and message,time frame and clock difference for Galileo system have been carefully studied again,and they are confirmed finally.Besides,the special attention has been paid on the joint operation with GPS system for satellite positioning customer.