介绍了北斗双星定位系统的特点、 功能、 系统组成和工作原理， 说明了北斗有源定位方式在应用方面的局限性.对搞BD无源定位而言，是篇很有用的论文，在此分享。-Introduced Beidou Positioning System features, functions, composition and working principle of the system, indicating the way Beidou active positioning application limitations. Right out BD passive positioning, the paper is very useful articles in this share .