Orbit and clock analysis of BDS-3 satellites using inter-satellite link observations
Orbit and clock analysis of BDS-3 satellites using inter-satellite link observations
复制标题
利用星间链路观测对 BDS-3 卫星进行轨道和时钟分析
DOI：
10.1007/s00190-020-01394-4
复制
发表时间：
2020-07-08
影响因子：
4.4
通讯作者：
Liu, Jingnan
中科院分区：
文献类型：
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作者：
Xie, Xin;Geng, Tao;Liu, Jingnan
中国目前正专注于其BDS-3系统的建立，自2018年底以来，由18颗中地球轨道卫星和1颗地球静止轨道卫星组成的BDS-3星座已能够提供初步的全球服务。这些BDS-3卫星配备了卫星间链路(ISL)和新的高质量星载时钟。在这项研究中，我们分析了由18颗MEO卫星和一颗GEO卫星的Ka波段ISL测量确定的BDS-3轨道和时钟。使用的是2019年1月1日至2月12日43天的ISL数据。BDS-3ISL测量采用双单向测距模型。在将双向观测转换为同一历元后，通过对双单向观测的相加和相减，分别得到了Ka波段无时钟观测和无几何观测。在定轨中引入了一个具有Ka波段双向观测的锚站，以提供定向约束。利用Ka波段无钟观测值，确定了BDS-3卫星的轨道。结合轨道估计了ISL的硬件时延，得到的硬件时延估计相当稳定，标准偏差约为0.03 ns。通过轨道重叠差、与L波段精密轨道的比较以及卫星激光测距验证，对Ka波段轨道进行了评估。结果表明，MEO卫星的径向轨道误差为2-4 cm，GEO卫星的径向轨道误差为8-10 cm。此外，通过增加一个锚点站和减少锚点站的数据量来考察其对地面的锚定能力。利用Ka波段无几何观测值估算了BDS-3卫星钟表，拟合后的ISL残差的均方根值约为5 cm。对Ka频段的时钟偏差进行了分析，并与L频段的精密时钟进行了比较。在不考虑轨道误差的情况下，S平均间隔大于5000的Ka频段时钟的艾伦偏差优于L频段时钟。此外，在L频段时钟的艾伦偏差中出现的一个显著的凸起在Ka频段时钟中几乎消失。最后，对L频段和Ka频段时钟的周期变化进行了检测。
China is currently focusing on the establishment of its BDS-3 system, and a BDS-3 constellation with 18 satellites in medium Earth orbit (MEO) and one satellite in geostationary Earth orbit (GEO) has been able to provide preliminary global services since the end of 2018. These BDS-3 satellites feature the inter-satellite link (ISL) and new high-quality onboard clocks. In this study, we present the analysis of BDS-3 orbits and clocks determined by Ka-band ISL measurements from 18 MEO satellites and one GEO satellite. The ISL data of 43 days from 1 January to 12 February 2019 are used. The BDS-3 ISL measurement is described by a dual one-way ranging model. After converting bidirectional observations to the same epoch, Ka-band clock-free and geometry-free observables are obtained by the addition and subtraction of dual one-way observations, respectively. One anchor station with Ka-band bidirectional observations is introduced into the orbit determination to provide the orientation constraints. Using Ka-band clock-free observables, BDS-3 satellite orbits are determined. The ISL hardware delays are estimated together with orbits, and the resulting hardware delay estimates are quite stable with STD of about 0.03 ns. The Ka-band orbits are evaluated by orbit overlap differences, comparison with L-band precise orbits, and satellite laser ranging validation. The results indicate that the radial orbit errors are on the 2-4 cm level for MEO satellites and 8-10 cm for the GEO satellite. In addition, we investigate the ground anchoring capability by adding one anchor station and reducing the amount of data of the anchor station. Using Ka-band geometry-free observables, BDS-3 satellite clocks are estimated and the RMS of post-fit ISL residuals is about 5 cm. The Ka-band clock offsets are analyzed and compared with L-band precise clocks. Independent of orbit errors, the Allan deviation of Ka-band clocks for averaging interval longer than 5000 s is superior to that of L-band clocks. Furthermore, a pronounced bump, which appears in the Allan deviation of L-band clocks, almost vanishes in Ka-band clocks. Finally, the periodic variations are detected for L-band and Ka-band clocks.