MGEX广播星历轨道和钟差的精度评估

为了对MGEX提供的广播星历产品进行精度评估，本文推导了广播星历计算卫星在地固坐标系下位置的数学模型，归纳了精密星历对广播星历进行评估的基本原理和方法，借助MGEX系统提供广播星历产品，对比分析了MGEX系统提供的GPS卫星广播星历轨道及钟差的误差平均值和RMS值。试验结果表明：除个别卫星轨道误差RMS超过4 m，钟差误差平均值大于8 ns外，MGEX提供的7 d和27 d的广播星历产品的轨道精度都优于3 m，钟差误差小于6.5 ns。本文为使用MGEX广播星历的用户提供了参考依据。

Accuracy evaluation of MGEX broadcast ephemeris orbit and clock correction

In order to evaluate the accuracy of the broadcast ephemeris provided by MGEX, the mathematical model of calculating the position of the satellite in the earth fixed coordinate system is derived, and the basic principle and method of evaluating the broadcast ephemeris by the precise ephemeris are summarized. With the help of the broadcast ephemeris products provided by MGEX system, the mean value and RMS value of orbit and clock error of GPS satellite broadcast ephemeris provided by MGEX system are compared and analyzed. The experimental results show that except the mean value of clock error is greater than 8 ns and the orbit error RMS of individual satellite is more than 4 m, the orbit precision of 7 d and 27 d broadcast ephemeris provided by MGEX is better than 3 m, and the clock error is less than 6.5 ns, which provides reference for users using MGEX broadcast ephemeris.