共查询到20条相似文献,搜索用时 93 毫秒
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本文对本地区电钢调度自动化系统的时钟现状、统一时钟的重要性及如何统一时钟进行了阐述和分析,对提高调度自动化系统的实用化功能、促进电网安全运行有普遍意义。 相似文献
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本文主要阐述了低轮廓平板动中通天线系统捕获、跟踪卫星的方法。低轮廓动中通天线利用捷联惯性系统辅助天线在初始状态下捕获卫星,利用电子波束倾斜的方法实现对信标信号和通信信号的捕获、跟踪,同时实现了当天线锁定卫星后通过接收机的差信号对惯性系统进行航向修正的功能。 相似文献
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本文主要论述了运用自行开发的计算机软件系统对网吧计时系统的检定,该套软件采用“比较法”进行检测,即将GPS卫星时钟计时间隔信号与被检系统时间计时间隔进行比较,得到被检系统时间的计时误差。并对这一检测系统进行了不确定度分析。 相似文献
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客观分析比较普通照明系统与智能照明系统的特点,运用自动化,智能化和信息化的技术手段达到节能降耗的目的。采用智能分段时钟控制照明供电,高效供电,采用高效智能节电设备优化系统供电,高效节能,采用信息化智能化软件进行远程集中监控,优化管理。从实际需求出发,进行系统架构设计,阐述了各模块的设计与实现,通过一系列的探索与实践最终实现了科学管理、高效节能的目的。 相似文献
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通过分析通信系统的高精度时频同步需求及现有检测方法的特点和适用性,选取卫星共视设备作为检测参考,对通信网络设备的频率和时间性能进行了实际检测,实现了卫星共视技术在通信同步设备检测中的应用.测试结果表明卫星共视技术能较好地满足目前通信同步网的检测需求. 相似文献
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为提高系统集成度,降低硬件开销,研究利用FPGA实现看门狗电路的方法,从而去掉硬件看门狗电路。对硬件看门狗电路的工作过程进行分析,给出利用FPGA实现看门狗电路的方法:利用FPGA的系统时钟对单片机送出的喂狗信号进行监测,当单片机由于程序跑飞而进入死循环后,喂狗信号消失,FPGA判定单片机工作异常,自动产生一个脉冲信号复位单片机。实验证明,利用FPGA实现看门狗电路定时精度更高,在1KHz系统时钟FPGA系统中,定时精度可以达到1ms。 相似文献
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星载原子钟是全球导航卫星系统的核心设备之一,其性能及钟差预报精度直接决定着导航定位授时服务的精度。针对卫星钟差组合预报技术中子模型权值难以确定的问题,将熵权法引入到北斗卫星钟差组合预报中。对卫星钟差数据中的粗差、钟跳等异常值进行相频域组合探测,并使用滑动拉格朗日内插法进行修补,得到“干净”钟差序列。以灰色模型和二次多项式模型作为基础模型,构建基于信息熵这一新的评价指标的钟差组合模型,建立北斗卫星钟差熵权组合预报模型。使用武汉大学IGS数据中心发布的北斗精密钟差数据产品,分别进行了连续多天的短期预报和中长期预报试验,多天的平均试验结果验证了熵权组合模型在北斗卫星钟差预报精度和稳定性方面较传统组合模型均存在一定优势。 相似文献
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A three-way time transfer system for comparing a satellite clock and a ground clock is described. It eliminates not only distance variations like a two-way system but also ionospheric signal delay by the third way. The accuracy of such a system is limited of course by signal-to-noise ratio but essentially by controlling the equipment delay times 相似文献
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Experimental demonstration of a compact and high-performance laser-pumped rubidium gas cell atomic frequency standard 总被引:2,自引:0,他引:2
Affolderbach C. Droz F. Mileti G. 《IEEE transactions on instrumentation and measurement》2006,55(2):429-435
The authors present a compact high-performance laser-pumped Rubidium atomic frequency standard exploiting the advantages of laser optical pumping for improved stability. The clock is based on an industrial Rb clock with the lamp assembly removed and optically pumped by light from a compact frequency-stabilized laser head. The modification of the buffer gas filling in the clock resonance cell reduces instabilities on medium-term timescales arising from the ac Stark effect and temperature variations. The frequency stability of the demonstrator clock was measured to be better than 4/spl times/10/sup -12//spl tau//sup -1/2/ up to 10/sup 4/ s, limited by the local oscillator (LO) quartz and RF loop electronics. Long-term drifts under atmosphere amount to 2-6/spl times/10/sup -13//day only, comparable to or lower than that for lamp-pumped clocks under similar conditions. Typical signal contrasts lie at around 20%, corresponding to a shot-noise limit for the short-term stability of 2/spl times/10/sup -13//spl tau//sup -1/2/. The results clearly demonstrate the feasibility of a laser-pumped Rb clock reaching <1/spl times/10/sup -12//spl tau//sup -1/2/ in a compact device (< 2 L, 2 kg, 20 W), given the optimization of the implemented techniques. Compact high-performance clocks of this kind are of high interest for space applications such as telecommunications, science missions, and future generations of satellite navigation systems [GPS, global orbiting navigation satellite system (GLONASS), European satellite navigation system (GALILEO)]. 相似文献
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回顾了中国科学院精密测量科学与技术创新研究院对钙离子光频标钟跃迁绝对频率的测量工作,并对测量结果被国际计量委员会(CIPM)下属的时间频率咨询委员会(CCTF)采纳的情况进行了总结和描述。在2011~2020年间,利用实验室型光频标和可搬运光钟,采用基于飞秒光梳和卫星链路的方案溯源到国际秒定义,及基于飞秒光梳直接溯源到中国计量科学研究院铯喷泉微波钟的方案,多次测量了钙离子光频标钟跃迁绝对频率,测量不确定度从10-15量级逐步提高到10-16量级,共计4个测量结果被CCTF采纳。参与钙离子光频标钟跃迁频率国际推荐值的计算,分别于2012年、2015年、2017年和2021年先后四次更新了钙离子光频标钟跃迁频率推荐值。钙离子光频标钟跃迁于2021年被推荐为新增的“秒的次级表示”。 相似文献
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In Global Navigation Satellite Systems (GNSS), atomic clocks are fundamental for their excellent stability. Being the distance measured from the time, any error on the measure of time leads to an error in the positioning: accurate and stable atomic clocks need to be employed on board satellites. Hence, the on board clock behaviour has to be continuously monitored and any malfunctioning has to be immediately detected. In this work, we illustrate a software tool developed at the National Institute of Metrological Research (INRIM) for GNSS clock characterization and monitoring. In particular we focus on the functionality of frequency drift estimation and removal, including the uncertainty evaluation. Actually, the frequency drift evaluation and the monitoring of its evolution over time is extremely important in GNSS applications to ensure the adequacy of the timing system to the integrity requirements of the positioning service. The software has been optimized for space clock data, which are different from the ones from timing laboratories, since often present missing data and outliers. The tool allows to easily handle satellite clock data, and get a quick estimate and graphic representation of clock key parameters, such as the clock frequency drift. 相似文献