考虑光行时校正的高精度全球导航卫星系统测速算法

High-precision Global Navigation Satellite System Velocimetry Algorithm Considering Light Travel Time Correction

全球导航卫星系统(GNSS)测速算法认为多普勒测量值为接收机与GNSS卫星的相对运动速度在视线方向上的投影,未考虑光行时的影响,存在一个微小的系统性偏差,测速精度不高,限制了其在精密测速领域中的应用。在传统的GNSS测速算法基础上,给出了一至三阶的积分多普勒插值算法,用瞬时多普勒替代了平均多普勒,对于低轨道地球卫星(LEO)用户,使用二阶插值积分多普勒的测速精度较使用平均多普勒的测速精度提升了三个数量级;另一方面考虑了光行时的影响,修正了因收发时刻不一致引入的多普勒偏差,并分别给出了地球惯性坐标系(ECI)和地球固连坐标系(ECEF)下的修正算法,实验结果表明,光行时修正算法降低了系统性偏差,三维速度误差的均方根(RMS)降低至3.3mm·s-1,能够满足高精度测速的应用需求。

The velocimetry algorithm of the traditional global navigation satellite system(GNSS)considers the fact that the Doppler measurement value is the projection of the relative motion velocity of the receiver and GNSS satellites along the line of sight direction,without considering the influence of light travel time.As a result,there is a small systematic deviation,and the velocity estimation accuracy is not high,limiting its application in the field of precision velocity determination.In this paper,based on the velocimetry algorithm of the traditional GNSS,a first-order to third-order integral Doppler interpolation algorithm is proposed.The instantaneous Doppler is used to replace the average Doppler,and the accuracy of velocity determination using second-order interpolated integral Doppler is improved by three orders of magnitude compared with the accuracy of velocity determination using average Doppler.Besides,the influence of light travel time is considered,and the Doppler deviation caused by the inconsistency of receiving and transmitting time is corrected,and the correction algorithms in the earth inertial coordinate system(ECI)and in the earth fixed coordinate system(ECEF)are given respectively.The experimental results show that the systematic deviation is eliminated,and the root mean square(RMS)of three-dimensional velocity error is reduced to 3.3 mm·s−1,which can meet the application requirements of high-precision velocity determination.