第一类无奇点变量的广播星历参数拟合算法

摘要

Broadcast ephemeris parameters are an important part of the navigation message,and usually can be obtained by parameter fitting the precise ephemeris.Most scholars adopt broadcast ephemeris parameters fitting algorithm based on Kepler elements,but research shows that the fitting accuracy of this method is poor in the case of small eccentricity.This paper gives broadcast ephemeris parameters fitting algorithm based on the first class of no singularity variables.The simulation shows that the algorithm can effectively avert the fitting accuracy loss caused by small eccentricity,fitting accuracy can reach millimeters;In addition,this paper discusses the adaptability of the algorithm in the case of small inclination,the simulation shows that the fitting algorithm is not suitable for small inclination.In the end,combining with the engineering application of autonomous navigation,this paper analyzes the extrapolation capability of navigation data and gives an initial scheme in which the fitting arc length of autonomous navigation data is for 2 hours,and the update interval is 15 minutes.%广播星历参数是卫星导航电文的重要内容,一般通过对精密星历进行参数拟合得到,广播星历参数的拟合大多采用基于开普勒根数形式的广播星历参数拟合算法,研究表明,该方法在小偏心率轨道情形下,拟合精度较差。文章给出了基于第一类无奇点变量形式的广播星历参数拟合算法,仿真结果表明,采用第一类无奇点变量,可以有效解决小偏心率引起的拟合精度损失问题,拟合精度可达毫米级;此外,讨论了小倾角情况下算法的适应性,仿真结果表明,基于第一类无奇点变量的广播星历参数的拟合算法不能很好地适应小倾角情况;最后,对导航电文的外推能力进行了分析