论文标题
案例研究分析，用于设计带有Earth-GPS的时间转移的月球导航卫星系统
A Case Study Analysis for Designing a Lunar Navigation Satellite System with Time-Transfer from Earth-GPS
论文作者
论文摘要
最近，人们对使用Smallsat平台的未来月球导航卫星系统（LNSS）越来越感兴趣，以实现成本效益和快速部署。但是，对于基于小的LNS，包括机载时钟和轨道类型，许多设计选择尚未完成。与传统的Earth-GP相比，设计LNSS带来了独特的挑战：（a）船时钟的限制尺寸，重量和功率（交换），从而限制了正时稳定性； （b）有限的月球地面监测站，这使得对稳定的LNSS卫星轨道更加偏爱。 在目前的工作中，我们分析了与船时钟相关的不同设计注意事项与使用Earth-GPS时间转移的LNSS设计的不同设计注意事项之间的权衡。我们提出的时间传输架构将间歇性可用的地球GPS信号结合在定时过滤器中，以减轻车载时钟的成本和交换要求。具体而言，我们进行了多种案例研究，具有不同等级的低S型钟和各种先前研究的月球轨道类型。我们估计LUNAR用户当量范围误差（UERE）度量，以表征从LNSS卫星传输的信号的范围准确性。使用Analytical Graphics，Inc。（AGI）的Systems工具套件（STK）的模拟设置，我们在LNSS设计的各种案例研究中评估了Lunar Uere，以证明与传统的Earth-GPS相当的性能，即使在使用板上的低swap时，也可以证明其性能。我们进一步执行灵敏度分析，以调查不同案例研究中月球UERE度量的变化，因为Earth-GPS测量更新速率变化了。
Recently, there has been a growing interest in the use of a SmallSat platform for the future Lunar Navigation Satellite System (LNSS) to allow for cost-effectiveness and rapid deployment. However, many design choices are yet to be finalized for the SmallSat-based LNSS, including the onboard clock and the orbit type. As compared to the legacy Earth-GPS, designing an LNSS poses unique challenges: (a) restricted Size, Weight, and Power (SWaP) of the onboard clock, which limits the timing stability; (b) limited lunar ground monitoring stations, which engenders a greater preference toward stable LNSS satellite orbits. In this current work, we analyze the trade-off between different design considerations related to the onboard clock and the lunar orbit type for designing an LNSS with time-transfer from Earth-GPS. Our proposed time-transfer architecture combines the intermittently available Earth-GPS signals in a timing filter to alleviate the cost and SWaP requirements of the onboard clocks. Specifically, we conduct multiple case studies with different grades of low-SWaP clocks and various previously studied lunar orbit types. We estimate the lunar User Equivalent Range Error (UERE) metric to characterize the ranging accuracy of signals transmitted from an LNSS satellite. Using the Systems Tool Kit (STK)-based simulation setup from Analytical Graphics, Inc. (AGI), we evaluate the lunar UERE across various case studies of the LNSS design to demonstrate comparable performance as that of the legacy Earth-GPS, even while using a low-SWaP onboard clock. We further perform sensitivity analysis to investigate the variation in the lunar UERE metric across different case studies as the Earth-GPS measurement update rates are varied.
