嫦娥三号多普勒测速数据时标偏差补偿

Compensation for time-tag bias of Doppler measurement from Chang'e-3 probe

―数据分析表明我国嫦娥三号月球探测器多普勒测速数据存在周期性系统差.根据多普勒测速模型和轨道信息,辅助多普勒测速信息含量分析,推导出周期性系统差产生的原因是测量数据的时标存在偏差,进而提出了自校准和差分统计校准两种补偿时标偏差的方法.计算结果表明,两种方法计算的嫦娥三号多普勒测速数据时标偏差一致.补偿时标偏差后,多普勒测速数据残差均方根(RMS)从1.5 cm/s降低到0.3 mm/s,无明显周期性系统差.以测距和甚长基线干涉(VLBI)测量数据联合定轨的结果为基准,利用时标偏差补偿后的多普勒测速数据联合VLBI测量数据进行定轨,其精度与基准轨道精度一致,位置偏差仅为2.5 m;利用时标偏差补偿后的多普勒测速数据联合测距数据进行定轨,与基准轨道的位置偏差为25 m;单独利用时标偏差补偿后的多普勒测速数据进行定轨,与基准轨道的位置偏差为200 m.

Data analysis shows there are periodic systematic errors in the Doppler measurement of the Chang’e-3 lunar probe. According to the Doppler measurement model and orbit information, as well as analysis of the Doppler information, periodic variation in the residuals is related to bias of the time-tag of the measurements.In this paper, self-calibration and differential statistical calibration methods are proposed to compensate this time-tag bias. The time-tag biases of the Jiamusi and Kashi deep space station estimated by these methods were 25 ms and 10 ms, respectively. The root mean square of the Doppler residual was reduced from 1.5 cm/s to 0.3 mm/s after the time-tag bias was compensated. The periodic variation in the residual was removed. In addition,the application of Doppler data in orbit determination was analyzed. Based on the orbit determination of ranging and VLBI data, the position error was only 2.5 m of the orbit determination using the compensated Doppler and VLBI data. The position deviation of the orbit determination obtained using the Doppler and ranging data was 25 m, and the position error of the orbit determination via Doppler data was 200 m.