摘要
现在通用的X射线脉冲星导航的3维观测方程,是以3颗脉冲星发射的脉冲到达航天器和太阳系质心的时间偏差为观测量建立起来的.在实际测量过程中,这个观测量是通过比较航天器探测到的脉冲观测轮廓与相应脉冲星的标准轮廓得到的,而在累积观测轮廓的同时也得到了观测轮廓的周期,因此根据Doppler速度测量方程,就能够确定航天器的速度矢量.本文首先导出Doppler速度测量方程,提出在观测轮廓的积累过程中考虑航天器的速度和加速度,得到的观测轮廓的周期不同于标准轮廓.这样,将探测3颗脉冲星得到的观测轮廓与相应的标准轮廓进行比较时,可以同时获得脉冲到达航天器和太阳系质心的时间偏差和频率漂移6个观测量,从而确定航天器的3维位置和3维速度.由于信息量增加一倍,6维观测方程比现行观测方程更为精确和完整.
3-D measurement equation in XNAV is discussed widely, which shows the relation between the observation and location of the spacecraft, using the deviations of TOAs–––relative to 3 pulsars–––between spacecraft and SSB as its observations. The deviation can be worked out from the comparison between the observation profiles and the standard profiles. Actually, during the epoch-folding process required for the observation profile, we also get the period of the profile. Then from Doppler velocity measurement formula, the velocity of the spacecraft can be determined. In the first part of this paper, we present the Doppler velocity measurement formula, and argue that when the acceleration of the spacecraft is considered, the period of the observation profile is different from the standard profile. Thus we can get 6 observations from comparison： 3 for TOA deviation, 3 for frequency drifting, and we can use these 6 observations together to determine the 3-D position and 3-D velocity of the spacecraft. Since the information we exploit is doubled, the 6-D measurement equation is of higher precision and integrity.
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2010年第5期644-650,共7页
Scientia Sinica Physica,Mechanica & Astronomica
