共查询到18条相似文献,搜索用时 521 毫秒
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守时型原子钟主要包括氢原子钟和铯原子钟,为进一步探究不同类型守时原子钟计算时间尺度相关性能,本文开展全氢钟及氢铯联合时间尺度研究。首先依据国际权度局(Bureau International des Poids et Mesures, BIPM)发布的d公报将氢原子钟进行分类,针对分类结果分别运用原子时尺度理论方法计算全氢钟时间尺度,并给出分析结果。随后计算全铯钟时间尺度,并分析探究两种不同的氢铯联合钟组时间尺度。结果表明,基于频率漂移量较小的氢钟组形成的时间尺度波动范围小,且稳定度优于频率漂移量较大的氢钟组形成的时间尺度。氢铯联合形成的时间尺度稳定度优于全铯钟时间尺度,不同的氢铯联合钟组计算得到的时间尺度结果相近。 相似文献
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地方原子时算法研究 总被引:1,自引:0,他引:1
产生和保持一个稳定、准确、可靠的时间尺度是所有时间实验室追求的目标.传统的ALGOS算法主要考虑时间尺度的长期稳定度,而地方原子时尺度需兼顾长、短期的稳定度.通过对原子钟噪声模型的分析研究,在保证地方原子时尺度长期稳定度不降低的条件下,提出适合中国科学院国家授时中心(National Time Service Center,NTSC)守时钟类型单一、钟性能相近的时间实验室计算地方时间尺度TA(NTSC)的一套完整算法.应用NTSC 2008年全年所有参加国际原子时(International Atomic Time,TAI)计算的钟的数据进行新算法的验证计算,得到的TA(NTSC)的短期稳定度指标与长期稳定度指标均有提高.研究结果适用于与NTSC守时系统结构相似的时间实验室的原子时尺度计算. 相似文献
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《天文学报》2018,(6)
主动型氢原子钟是时间尺度建立和保持的主要频率源,具有短期稳定度高及相位噪声低等特性,目前在国际原子时TAI (International Atomic Time)及各地方时间尺度中的作用日益重要.首先结合主动型氢原子钟内部状态参数,分析状态参数与氢原子钟比对数据的相关性,提出了氢原子钟性能监测方法.其次,针对氢原子钟性能特点,在衡量氢原子钟性能最主要的两方面,即频率稳定度及"可预测性"方面,给出了氢原子钟性能评估方法,并利用该方法对目前国际通用的两种主动型氢原子钟(CH1-75型及MHM-2010型)进行性能评估.原子钟状态参数与比对数据联合分析结果表明,状态参数监测可以有效预报钟性能的变化.原子钟频率稳定度及"可预测性"评估结果表明,中、长期稳定度越高的原子钟"可预测性"也越好. BIPM (Bureau International des Poids et Measures)权重验证结果表明,基于BIPM公布数据以及基于2次模型两种预报方法计算出来的钟"可预测性"均与BIPM公布的权重相吻合,可以作为钟"可预测性"的定量评估方法. 相似文献
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由单脉冲星定义的脉冲星时受几种噪声源的影响,为削弱这些影响得到一种更稳定的时间尺度,采取将多颗脉冲星定义的单脉冲星时进行综合的分析方法得到综合脉冲星时.用两种方法:经典加权算法和小波分解算法,对PSRB1855 09和PSR B1937 21两颗脉冲星进行综合计算并做出比较,经典加权算法无法兼顾脉冲星不同频率上的稳定度,而用小波分析的方法对PSR B1855 09和PSR B1937 21两颗脉冲星进行综合,能够有效抑制不同频率上噪声的影响,达到更好的效果. 相似文献
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原子钟通过稳定的频标来测量时间,但频标输出信号会受到不同来源噪声的影响,因此原子钟间相位偏差可以看作服从幂律∑hαfα的连续随机过程。该随机过程并非平稳的,一般是通过高阶的差分使得序列平稳化,常用的时域频率稳定度评估方法便是采用此种思路。幂律噪声实际是对白噪声过程进行微分和积分得来,不同幂律的噪声对应不同的随机微分方程,实际上幂律噪声的仿真也是通过白噪声基于此实现的。首先介绍了不同幂律噪声的鉴定方法,并结合文献给出常见幂律噪声对应的微分方程;然后介绍了不同频率稳定度评估方法之间的关系和其相应的传递函数,并简单总结了其置信区间的计算方法。该文的工作有助于构建原子钟随机模型和频率稳定度评估方法。 相似文献
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由单颗脉冲星定义的脉冲星时受多种噪声源的影响,其短期和长期稳定度都不够好.为了削弱这些噪声源对单脉冲星时的影响,可以采取合适的算法对多个单脉冲星时进行综合得到综合脉冲星时,从而提高综合脉冲星时的长期稳定度.文中介绍4种综合脉冲星时算法:经典加权算法、小波分析算法、维纳滤波算法和小波域中的维纳滤波算法,将这4种算法分别应用于Arecibo天文台对两颗毫秒脉冲星PSR B1855+09和PSRB1937+21观测得到的计时残差并作出比较. 相似文献
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原子钟噪声的蒙特卡络模拟方法 总被引:1,自引:0,他引:1
讨论了原子钟噪声的蒙特卡络模拟方法.具体过程是:先产生模拟所需的正态分布随机数,从实际钟的阿仑方差估算出噪声电平,然后用1组递点函数产生高质量的模拟钟时差的随机序列.在对1台商品铯钟进行具体模拟后,给出了真实数据与模拟值的阿仑方差之问的相符程度,最后对实际问题进行了分析. 相似文献
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《Chinese Astronomy and Astrophysics》2019,43(2):292-304
Active hydrogen maser is the main frequency standard for establishing and maintaining the time scale. It has the characteristics of high short-term stability and low phase noise. At present, it plays an increasingly important role in the international atomic time (TAI) and various local time scales. Firstly, in combination with the internal state parameters of an active hydrogen maser, the correlation between the internal state parameters and the comparison data of a hydrogen maser is analyzed, and a method for the performance monitoring of a hydrogen maser is proposed. Secondly, according to the characteristics of hydrogen maser performance, a method for evaluating the performance of a hydrogen maser is given. The hydrogen maser performance includes mainly two aspects, namely the frequency stability and predictability. The performances of two types of active hydrogen masers (CH1-75 and MHM-2010) are evaluated by this method. The correlation analysis of the atomic clock state parameters and comparison data shows that the state parameter monitoring can effectively predict the variation of the hydrogen maser performance. The evaluation results of atomic clock frequency stability and predictability show that the atomic clock with a higher medium-and-long term frequency stability has a better predictability. There are two methods for the predictability evaluation, one is based on the data published by BIPM (Bureau International des Poids et Measures), and another one is based on the quadratic model. Both methods are consistent with the weights published by BIPM. Therefore, the two methods can be used as a quantitative method to evaluate the predictability of a hydrogen maser. 相似文献
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The real-tine and accurate knowledge of the operation of an atomic clock is of great significance to satellite navigation and time keeping. In the light of the problems which exist in the real-time solution of the atomic clock operating parameters by means of the standard Kalman filtering, the method for applying the adaptive Kalman filtering model based on the prediction residual to the real-time solution of the clock parameters is proposed. An adaptive factor is constructed by the model based on the standard Kalman filtering model so that the accurate and reliable estimates of the operating parameters may be given rather fast after the frequency modulation or phase modulation of the atomic clock. Finally, in combination with the 3 computational examples of the work on the navigation and time keeping, the effectiveness of the method is verified. 相似文献
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Wang Ji-gang Hu Yong-huiHe Zai-min Wu Jian-feng Ma Hong-jiaoWang Kang 《Chinese Astronomy and Astrophysics》2011,35(3):318
The prediction of the clock errors of atomic clocks plays an important role in the work on time and frequency. Each of the prediction models often used at present has its own merits and shortages. A combination of the predicted results obtained by means of these models can be used to synthesize the characteristics of various kinds of prediction models. In the light of the problem which occurs when the linear combination model is used to make the prediction of clock errors, the concept of learning weight is proposed and the modified combination prediction model is made by taking advantage of various kinds of pieces of accuracy information. For verifying the efficiency of this method the clock error sequences of the IGS (International GNSS Service) of 4 GPS satellites are selected and the predicted results of the quadratic polynomial and grey model are combined. The result shows that the modified model can further improve the stability and accuracy based on the guarantee of the reliability. 相似文献
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Because of the effects of various kinds of noises and other factors, the state of running of an atomic clock is quite complicated. In order to precisely predict the exact variation in frequency or clock rate of the atomic clock, it is necessary to study and make a reliable prediction model and via the model the clock rate of the atomic clock is predicted so as to be adopted in the monitoring of the coordinated local time and the calculation of the local atomic time. The problem how to utilize the grey model and autoregressive model to predict the clock rate of the atomic clock is discussed. The synthesized model of the two models is proposed and researched. It is tested and verified in combination with the actual data of the atomic clocks at National Time Service Center, and the computational methods of predicting the accuracies of the models corresponding to different atomic clocks are given. 相似文献
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用脉冲星钟作航天器时间标准 总被引:3,自引:0,他引:3
在介绍参考坐标系和时间标准的基础上,讨论了用脉冲星为航天器导航的时间标准问题。利用X射线脉冲星实现航天器自主导航,星载钟的任何误差都会直接影响航天器位置测量。脉冲星钟具有较高的长期频率稳定度,适合用作各类航天器的时间标准。重点讨论了时间标准误差对航天器定位的影响;给出了用脉冲星钟作航天器时间标准的物理实现方法。 相似文献