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首页> 外文期刊>South African Journal of Geology: Being the Transaction of the Geological Society of South African: Syndie die Verhandelinge van die Geologiese Vereniging van Suid-Afrika >Design of the timing system for the new Lunar Laser Ranger proposed for the Matjiesfontein Space Geodetic Observatory in the Great Karoo, South Africa: preliminary results
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Design of the timing system for the new Lunar Laser Ranger proposed for the Matjiesfontein Space Geodetic Observatory in the Great Karoo, South Africa: preliminary results

机译：南非伟大的卡罗·斯卓菲恩坦空间大地测量师的新农历激光游侠时序系统设计：初步结果

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The Hartebeesthoek Radio Astronomy Observatory (HartRAO) in South Africa is developing an observational system capable of ranging picosecond laser pulses to the retro-reflectors on the Moon, a technique called Lunar Laser Ranger (LLR). The new LLR station in the Southern Hemisphere to be installed at Matjiesfontein in the Karoo, will contribute towards a better understanding of the dynamics of the Earth-Moon system. One of the most fundamental applications of the LLR system is to determine the Earth-Moon orbit parameters at high accuracy levels. As the observable of the LLR technique is the time-of-flight of the laser photons to and from the Moon, a picosecond level (1 picosecond = 10~(-12) second) accuracy timing system is one of the key design considerations required for the new LLR system. Here were present preliminary results of an integrated design of the timing sub-system for the HartRAO LLR station. All sub-systems that directly affect the timing system performance are described, including operational and environmental conditions. Based on the specifications of the equipment under consideration, preliminary results indicate that the timing sub-system will achieve a sub-picosecond Allan deviation at 1 s, phase noise of -113 dBc at 1 Hz, and a drift rate of 5 × 10~(-11) per month (free run). Furthermore, the cumulative RMS noise from the proposed system is estimated to be 21 mm per pulse. This noise level will require the station to range to the Moon for a longer period (at a rate of 5 photons per minute) in order to collect adequate photons to statistically achieve millimetre precision for normal point calculation. The current design specifications present a promising future for millimetre ranging at HartRAO.
机译：南非哈特贝斯霍郡射频天文学天文台（Hartrao）正在开发一种能够在月球上的复古反射器中的岩秒激光脉冲的观测系统，这是一种称为月球激光游侠（LLR）的技术。南半球的新LLR车站安装在卡罗的Matjiesfontein，将有助于更好地了解地球系统的动态。 LLR系统最基本的应用是以高精度水平确定地球轨道参数。随着LLR技术的可观察到的是激光光子往返月球的飞行时间，皮秒（1 picoSecond = 10〜（-12）秒）精度定时系统是所需的关键设计考虑之一对于新的LLR系统。以下是Hartrao LLR站的时序子系统的集成设计初步结果。描述了直接影响定时系统性能的所有子系统，包括操作和环境条件。基于所考虑的设备的规格，初步结果表明时序子系统将以1 Hz为-113 dBc的1 s，相位噪声达到亚皮秒偏离偏差，漂移率为5×10〜 （-11）每月（免费运行）。此外，来自所提出的系统的累积RMS噪声估计为每次脉冲21 mm。这种噪声水平将要求车站更长的时间（以每分钟的5光子的速率）到月球范围，以便收集足够的光子以统计地实现毫米精度以进行正常点计算。目前的设计规范为毫米的毫米提供了一个有希望的未来。

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