“嫦娥4号”中继星开环测速方案设计与试验验证

针对深空探测器轨道测量任务高精度测速需求,提出了一种开环测速方案。首先,采用窄带模式对深空探测器下行信号进行采集记录,利用傅里叶变换+线性调频Z变换+本地重构相关联合信号处理方法,对探测器主载波信号进行处理,自适应提取探测器主载波频率;然后,基于主载波频率获取反映探测器相对于测站速度运动关系的多普勒频率,并评估多普勒频率的随机噪声水平;最后,将基于本文的多普勒频率与深空站测速基带多普勒频率、累积载波相位测速多普勒频率进行比对,并将3种多普勒频率输入探测器联合定轨程序,进一步评估本方案获取的多普勒测速绝对精度。基于"嫦娥4号"中继星在轨实测试验数据分析表明:所获得的多普勒频率提取精度为10 m Hz,优于深空站基带测速多普勒频率与累积载波相位测速多普勒频率精度;联合定轨表明:多普勒测速绝对精度为0.2 mm/s,有效验证了深空开环测速技术,为后续深空探测器轨道联合测量系统研制奠定了技术基础。

Open Loop Velocity Measurement Scheme Design and Verification of Chang'E-4 Relay Satellite

An open loop velocity measurement scheme is proposed for the high accuracy orbit measurement mission of deep space probes. Firstly,deep space probe''s downlink signal is sampled and recorded by narrow band model. Then,the probe''s carrier signal is processed to extract carrier frequency based on the combining signal processing method,which contains FFT,CZT and local re-construction algorithms. Then,the probe''s Doppler frequency is obtained and Doppler frequency''s random noise level is estimated. Finally,thethe Doppler frequency obtained by the proposed method is compared with the Doppler frequency based on the deep space station''s baseband velocity measurement and the accumulation carrier phase velocity measurement. The three types of Doppler frequency are utilized for the input observations of orbit determination system to evaluate the absolute accuracy of the three types of Doppler frequency. The real signal processing and analysis of the on-orbit CE-4 relay satellite shows that, the Doppler frequency accuracy in this paper is at the level of 10 mHz,which is better than the Doppler frequency based on the deep space station''s baseband velocity measurement and the accumulation carrier phase velocity measurement. The probe high accuracy orbit determination results show thatthe velocity measurement absolute accuracy in this paper is at the level of 0.2 mm/s. The effectiveness of the open loop measurement technology is successfully evaluated for China''s future deep space missions.