GPS广播星历的时间序列分析

Time Series Analysis of GPS Broadcast Ephemeris

选取6颗GPS卫星近15年的广播星历进行研究,分析每颗卫星的轨道长半轴、扁率、参考时刻的轨道倾角、升交点赤经、近地点角距和真近点角距等开普勒六参数的时间序列,统计其最值及趋势项,通过功率谱分析,计算每个序列的主要周期项。结果表明:卫星轨道长半轴、扁率、轨道倾角、近地点角距有明显的趋势项,升交点赤经每周会产生一次7°左右的跳变,真近点角没有明显的趋势项。功率谱分析表明开普勒六参数均具有明显的周期项。

The time series of broadcast ephemeris for last 15 years are studied.Six GPS satellites are selected,which include 1 Block II,2 Block IIA,2 Block IIR,and 1 Block IIR-M.We focus on six Kepler parameters,which include semi-major axis of orbital ellipse（a）,eccentricity of the orbit（e）,inclination（i）,the right ascension of the ascending node（Ω）,argument of perigee（ω） and true anomaly（M）.The chart of time series are shown in the paper,the maximum values and the trends of the series are found.Obviously trends are existed in the time series of a,e,i,Ω,and ω.The time series are transformed into frequency domain using the FFT.There is a main period of about 280 days in the a,e,ω,and M,140 days in the i and 1 month in the Ω.