VLBI相时延及其在深空探测器测定轨中的应用

甚长基线干涉测量(very long baseline interferometry,VLBI)技术是深空探测器测定轨的方法之一,也是行星无线电科学研究的重要手段.VLBI相时延通过解算相关相位的整周模糊度解算出探测器的VLBI时延观测量,可有效地降低相位随机误差的影响,从而提高时延测量的精度.本文论述了解算相位整周模糊度的条件和方法,给出相时延的解算方法,并分析比较了相时延与群时延的随机误差水平.以嫦娥二号(CE2)卫星飞往拉格朗日L2点的探测任务为例,求解了两个月内10次VLBI观测的相时延并分析了数据质量.相时延和群时延分别联合测速测距数据的定轨结果表明,在150万公里的距离上相时延用于探测器的定轨是可行的.

VLBI phase delay and its application in orbit determination of spacecraft

As one of the key technologies for orbit determination, very long baseline interferometry （VLBI） will play an important role in deep space explorations. The traditional group delay of VLBI is affected by the signal to noise ratio （SNR）. As the spacecraft going to outer space, the random error of group delay increases quickly because of the SNR getting worse and worse. In this paper, we introduce the phase delay whose random error is much smaller than that of group delay at the same SNR. We deduce the conditions and method to determine the phase ambiguity, and then give the formula of calculating phase delay. The phase delay is used to determine the orbit of Chang＇e 2 （CE2） satellite which is 1 500 000 km away from with Doppler/ranging data when it the Earth. It proves that the phase flies to the Sun-Earth Lagrangian point L2 delay is useful for orbit determination.