天问一号星载USO的长期漂移标定

Estimation of USO frequency drift using one-way Doppler measurements for Tianwen 1

  • 摘要: 星载USO为发射机提供频率源,其稳定性直接影响单程多普勒测量精度,利用单程多普勒数据开展定轨计算需一并解算下行频率与标称频率的偏差。论文推导了单程多普勒观测模型及观测偏导数,分析了影响测量精度的主要误差源;对天问一号单程多普勒数据进行处理,在轨道解算的同时估计了频率偏差,并构建了USO长期漂移预报模型;给出了下行频率解算精度的影响因素,理论分析了频率解算精度。结果表明天问一号星载USO长期漂移率为(0.07575±0.00620) Hz/d。因此,本文提供了一种可行的星载USO漂移标定方法,构建了天问一号星载USO下行频率的先验模型。

     

    Abstract: Objectives The stability of Ultra Stable Oscillator (USO) which provides frequency standard and transmits downlink signal affects the accuracy of one-way Doppler measurements directly. It is a necessity to estimate the frequency bias during orbit determination with one-way Doppler measurements. Methods The one-way Doppler observation model and observation partial derivative are deduced theoretically, and the main error sources affecting the accuracy are analyzed. Then, the frequency deviation is estimated and the USO long-term drift prediction model is constructed during the execution of Tianwen-1 precise orbit determination using the one-way Doppler measurements. Finally, The frequency bias resolution accuracy is analyzed theoretically based on the analysis of its key factors. Results The results show that the USO drift rate is (0.07575±0.00620)Hz/d. Conclusions This paper provides a feasible frequency drift calibration method for Space-borne USO, and constructs a priori frequency model for space-borne USO of Tianwen 1.

     

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