低轨卫星广播星历参数设计

Design of Broadcast Ephemeris Parameters for LEO Satellites

导航增强卫星从高轨拓展到低轨(LowEarthOrbit,LEO),需要针对低轨卫星设计可靠的广播星历参数模型。传统的广播星历主要针对中高轨卫星设计,如果直接用于受摄动力更复杂的LEO卫星,星历拟合的URE精度难以达到要求。针对低轨卫星的受力特性,在ECEF坐标系内分别利用多项式和多项式+周期项2种方案来进行经验力(除地球扁率以外的摄动力)建模,设计了2种基于轨道列表型的16参数广播星历参数模型;将拟合时间设定为卫星的地面最大可见时间,以减少用户更新星历频率。300~1500km高度的轨道拟合实验表明,利用多项式+周期项建立经验力的16参数星历拟合精度更高,其R/T/N三个方向拟合误差分别优于10/10/3cm,URE优于9cm。

It is necessary to design a reliable broadcast ephemeris for LEO satellite when the navigation augmentation satellites expand from high orbit to low orbit. The traditional broadcast ephemeris is mainly designed for medium and high orbit satellites. If it is directly used for LEO satellites with more complex perturbations,it will be difficult for the URE accuracy of ephemeris fitting to meet the requirements. Considering the force characteristics of LEO satellites,the empirical force (perturbation force except the earth oblateness) is modeled by using polynomial and periodic terms in ECEF coordinate system,and two 16-parameter broadcast ephemeris parameter models based on orbital list are designed. The fitting time is set as the maximum visible time of the satellite to the ground to reduce the user’s ephemeris updating frequency. The orbital fitting experiments at altitudes of 300 ~ 1 500 km show that the 16 - parameter ephemeris using polynomial plus periodic term to establish empirical force has higher fitting accuracy,and the fitting errors of R / T / N in three directions are better than 10/ 10/ 3 cm respectively,and the URE is better than 9 cm.