伪卫星辅助的北斗定位系统的GDOP研究

我国建成的北斗导航定位系统由于卫星数目有限，不能实现实时三维无源定位．若利用地面伪卫星辅助，则能够很好地弥补这一缺陷，在地面伪卫星的作用范围内实现高精度的无源定位．卫星定位系统的精度等性能，很大程度上取决于定位卫星的数目和几何布局，而GDOP正是衡量定位卫星几何布局优劣的一个量度．本文从GDOP的角度研究了不同伪卫星位置及布局对系统定位精度的影响，得到的结论为合理设置伪卫星以进一步提高系统性能提供了有力的参考依据．

The Research on GDOP of PL-Aided Beidou Positioning System

The Beidou Positioning and Navigation System in the stand-alone mode cannot accom-plish real-time 3-D passive positioning due to the limited number of constellation,but when aidedby Pseudolites,through which the number and geometry of constellation is improved,it is capableof realizing high-precision passive positioning.Pseudo-satellites,also called pseudolites(PLs),whichare the transmitters of navigation satellite-like signals,have the similar principle and function asspaceborne satellites,hence can provide the additional ranging source and thereby improving thegeometry and increasing the accuracy,integrity,availability and reliability of the positioning results.And by simple,software only modifications,an existing satellite receiver can acquire PL signals andderive pseudoranges or carrier-phase measurements to be used in a navigation algorithm.As wellknown,such performances as accuracy of satellite-based positioning system are heavily dependenton the number and geometric distribution of satellites being tracked,and GDOP is a right measureof the geometry of the constellation.Therefore in the paper,the impacts of various locations andgeometries of PLs on the accuracy of the augmented system are comprehensively investigated basedon GDOP,and the conclusions obtained are the useful references for configuring PLs rationally as toimprove further the performances of the system.