中文摘要：

针对低轨卫星快速空间几何变化和抗干扰能力强等特征,该文基于卫星工具包软件对全球导航定位系统和铱星系统星座进行了仿真,并假定铱星具有导航卫星的功能,分析铱星对GPS定位的增强作用。首先对GPS和铱星增强星座的可见卫星数量和几何精度因子值进行了分析,然后通过对不同的误差值建模,对GPS系统和铱星系统的观测值进行了仿真,分析了低轨卫星对双差定位浮点解和模糊度固定的增强作用,结果表明：低轨卫星的加入增加了可见卫星数量,几何精度因子也优于单GPS系统。单频双差模糊度浮点解的RMS值优于1周,双频双差模糊度浮点解的RMS值优于0.5周,与单GPS相比有了较明显的提高,同时,低轨卫星的加入更有利于单频短基线的模糊度固定。

英文摘要：

Aiming at rapid changes of space geometry and strong anti-interference ability of low-orbit satellite features,this paper simulated global navigation positioning system and Iridium constellation based on STK soft ware,and supposed that Iridium had the function of navigation satellites, analyzed Iridium augmented effects on GPS. First,the number of visible satellites and GDOP value were analyzed, then different error model was built based on simulated observation of GPS and Iridium system, float solution and fixed ambiguity of aumgented double differential positioning was analyzed. Results indicated that the number of visible satellites was more, and the GDOP value was better than single GPS system. The RMS value of double differential ambiguity for single frequency was better than 1 cycle,the Accuracy of double differential ambiguity for double frequency was better than 0.5 cycle, which was improved obviously comparing with GPS system. Meanwhile,augmented positioning benefited ambiguity resolution for short baselines by using LEO satellites.