北斗卫星导航定位系统星座复杂、不同种类卫星高度差异较大，本文将全局性非线性最小二乘算法(Bancroft算法)应用到北斗单点定位中，Bancroft算法主要依据四维空间下的一种Lorentz内积实现，将Bancroft算法中的Lorentz内积方程写成误差方程形式，推导此方程的权，得到一种新的北斗观测值定权公式。为了验证上述定权方法，基于伪距相位差值(CC组合)组合观测值分析了北斗GEO、IGSO和MEO卫星的测距信号质量，基于多路径(MP组合)组合观测值分析了多路径效应对单点定位的影响。结果表明，新算法提高了北斗单点定位精度。

The constellation of BeiDou Navigation Satellite System is composed of Geostationary Earth Orbit (GEO) satellites and Non-Geostationary Earth Orbit (Non-GEO) satellites. In consideration of the huge difference between GEO satellites altitude and Non-GEO satellites altitude, the global nonlinear least squres algorithm(Bancroft algorithm) is applied for BDS single point positioning in this paper. The Bancroft algorithm based on the Lorentz inner product is mainly in four dimensional space. A new algorithm to get the BDS observation weight is introduced by transforming Lorentz inner product into error equation, and then weight of the error equation is deduced. In order to testify the method, a code-minus-phase combination (CC) of BDS measurements is used to determine the code noise of GEO and Non-GEO satellites, a multipath combination (MP) is introduced to extract the multipath of pseudorange and improve the accuracy of single point positioning. The result indicates that new algorithm can improve the accuracy of BDS single point positioning.