中文摘要：

针对因北斗地球静止轨道（GEO）卫星的小倾角特性,经典全球卫星定位系统（GPS）广播星历拟合算法不能直接应用于北斗GEO卫星这一问题,提出了一种基于无奇点变换的北斗GEO卫星广播星历直接拟合算法.该算法采用一组无奇点轨道根数代替经典轨道根数,解决了由GEO轨道的小倾角特性引起的经典广播星历拟合过程中法化矩阵奇异的问题;同时,避免了接收机GEO广播星历参数用户算法中坐标旋转的过程,减少了GEO用户算法的计算步骤.经仿真验证：该算法可很好地适用于北斗GEO卫星广播星历拟合,且拟合精度高,完全满足接收机导航定位的精度.但对于圆地球轨道（MEO）和倾斜地球同步轨道（IGSO）卫星,该算法实用性较差,仍须进一步研究和改进.

英文摘要：

The classic global positioning system（GPS）broadcast ephemeris fitting algorithm cannot be directly applied to BeiDou geostationary earth orbit（GEO）satellite because of its small inclination angle.Aim at this limitation,a broadcast ephemeris direct fitting algorithm of BeiDou GEO satellite was presented based on non-singular transformation.In this method,the classical orbit elements were replaced by a non-singular orbit elements,making all the broadcast ephemeris parameters definitely defined,and then the problem that coefficient matrix was non-positive was solved.Since this approach avoided the coordinate rotation process in the ephemeris algorithm of BeiDou GEO satellite for user, then the calculating steps were decreased and the GEO ephemeris algorithmic efficiency was enhanced. The simulation results show that this algorithm with high accuracy is well fit for broadcast ephemeris fitting algorithm of BeiDou GEO satellite,which can meet the requirement of the users fully.As for the BeiDou medial earth orbit（MEO）and inclined geosynchronous orbit（IGSO）satellite,the adaptability and utilization of this algorithm are poor,and it need further discussion and to be improved.