原子钟相位一时间起伏周期的小波分析

文中根据小波变换的奇异性检测原理，分析了环境温度变化对原子钟特性的影响。基于小波变换的信号重建原理，将温度变化引起原子钟相位-时间起伏进行时-频域分离。用小波变换理论分析了由于昼夜温度变化引起原子钟周期性波动的原因，结合传统的港分析方法，认证了原子钟相位－时间起伏的周期性。结果表明：在有环境温度调节的环境中，氢原子钟的相位－时间起伏标准差41ns左右，在一般环境中，她原子钟的相位一时间起伏标准差21us左右。改善环境条件可以提高原子钟的频率稳定度。     

守时系统钟组规模技术验证

通过分析氢原子钟和铯原子钟的频率稳定度和影响原子钟性能的噪声类型,将两种元素原子钟的仿真运行与实际运行数据进行对比。应用ALGOS算法对各类钟组配置进行原子时计算和溯源周期为五天的时标计算和性能分析以及无溯源条件下的自主守时性能。结果表明：溯源状态下,氢钟占比越高,钟组频率稳定度和时间稳定度越好,且自主守时能力也相对越强。氢钟作为守时钟组可得到较好的钟组性能,而铯钟的价格更具优势,所以可按实际使用需求选择原子钟。     

传输高稳定原子钟信号的光纤模拟通信系统

采用光纤模拟通信技术,对某微波通信站高稳定的原子钟信号进行光纤传输,设计专用光纤模拟通信设备,并分析影响原子钟信号短期频率稳定度的主要因素,同时给出减少影响的有效方法。通过设备研制和实验对比．结果证明,经光纤模拟传输后,原子钟信号的短期频率稳定度达到某微波通信站的应用要求。     

传输高稳定原子钟信号的光纤模拟通信系统

采用光纤模拟通信技术,对某微波通信站高稳定的原子钟信号进行光纤传输,设计专用光纤模拟通信设备.并分析影响原子钟信号短期频率稳定度的主要因素.同时给出减少影响的有效方法.通过设备研制和实验对比.结果证明.经光纤模拟传输后.原子钟信号的短期频率稳定度达到某微波通信站的应用要求.     

被动型氢原子钟单频调制原理分析

单频调制技术具有调制频率高、环路参数限制小的优点,对降低原子钟环路噪声、提高中短期频率稳定度具有重要的意义。文章基于被动型氢原子钟,讨论了频调制技术的应用并进行了相应的理论计算分析,为今后该技术的进一步应用提供参考。     

氢钟频移校准与相位无损切换

为满足VLBI等高精度空间测量技术对时间频率稳定度和准确度提出的更高要求,深空测控系统都配置了高性能的氢原子钟。但由于部件老化、环境变化等影响,氢原子钟输出频率会发生漂移变化,需要对此频移进行校准;同时备份原子钟需要追踪并保持与主钟的输出相位一致,必须进行相位的无损切换才能保障时频信号的连续性。分析了氢原子钟的工作原理和调频移相技术,设计了一种氢钟追踪外部授时系统进行频率漂移校准、主备钟相位无损切换的工程实施方法。应用结果表明,72 h测试时间内,与GPS相比,氢钟的稳定度由原来1.1×10-13提高到3.2×10-14,主备氢钟相位差由原来1.03o减小至0.08o,满足了VLBI长时间高精度测量的精度需求。     

综合原子时软件中联合守时方法的探究

<正>综合原子时软件采用加权平均算法，以各钟频率稳定度作为取权依据，根据原始钟差测量数据和利用原子钟模型预报的钟差改正数据计算产生综合原子时，再经过频率驾驭实现向外部标准时间溯源。同时，通过计算各原子钟的频率稳定度、频率偏差、频率漂移、数据质量、预报质量等指标对原子钟性能进行评估^[1]。     

卫星导航系统星载钟时域频率稳定度探讨

介绍了四大卫星导航系统采用的时间系统,分析了频率标准的时域频率稳定度研究内容、研究方法,推导了其实用计算方法和公式,主要对近十年以来研究GNSS星载原子钟频率稳定度的测算数据进行了梳理和归纳总结,对比分析了各个导航系统星载原子钟的频率稳定度,综合数据表明大部分星载钟天稳均可达到10^-14量级,其中GPS星载铷钟和Galileo星载PHM钟稳定性最好。     

星载MEMS原子钟稳频系统的优化及实验研究

简要介绍CPT原子钟工作原理,讨论原子频标的两个重要指标:短期稳定性和频率漂移.对CPT原子钟的锁频伺服控制电路进行系统分析和优化设计,并通过饱和吸收稳频实验验证所设计伺服控制电路的稳频性能,100 s的频率稳定度达到1.6×10-12,有望进一步提高频率稳定性.     

星载MEMS原子钟稳频系统的优化及实验研究

简要介绍CPT原子钟工作原理,讨论原子频标的两个重要指标：短期稳定性和频率漂移。对CPT原子钟的锁频伺服控制电路进行系统分析和优化设计,并通过饱和吸收稳频实验验证所设计伺服控制电路的稳频性能．100s的频率稳定度达到1．6×10^-12,有望进一步提高频率稳定性。     

氢脉泽中四极磁态选择器的设计及其应用

氢脉泽是一种中、长期稳定度最高的原子频率标准.其中原子磁态选择器的改进设计可以改善氢脉泽的工作参数及其体积与重量,从而改进氢脉泽的品质与工作寿命等,同时也可以改进氢脉泽的长期性能,并给出了磁态选择器的设计与实验结果.     

The optically pumped rubidium maser

The optically pumped rubidium maser oscillator is the most recent addition to a growing number of atomic frequency standards. It is the first atomic frequency standard which is small enough and simple enough to be considered as a replacement for crystal oscillators. These factors and the extreme phase stability which results from the maser action make this device unique among all frequency standards. The device generates a microwave output at the ground-state hyperfine frequency of Rb⁸⁷(6835 Mc/s). The maser consists of a microwave cavity filled with Rb⁸⁷vapor and nitrogen gas. Oscillation occurs when the vapor is illuminated with filtered rubidium resonance radiation. The power output of the maser is 10^-10watts, and higher powers can be expected. In this paper the physical principles and construction of the device are described. The effects of optical pumping, buffer gas, and temperature on the maser are discussed, and experimental results are given. The short-term stability for observation times of about one second is expected to be about one part in 10¹². This may be increased by an order of magnitude by increasing the powser output to 10^-8watts. The long-term stability is expected to be comparable to that obtained in the passive rubidium standard (about one part in 10¹¹per month). These slow fluctuations arise from pressure shifts, light shifts, cavity pulling, and changes in the chemical composition of the buffer gas. The long-term stability can be improved by using the rubidium maser as the flywheel for an atomic beam frequency standard. Such a combination could be expected to have both long-term and short-term stabilities as great as one part in 10¹³.     

基于异频相位处理的新型氢原子频标锁相系统

 在等效鉴相频率的基础上,提出了一种新型氢原子频标锁相系统的设计方案.利用频率信号间相位差变化的规律性,无需频率归一化便可完成相互间的线性相位比对即异频鉴相.将异频鉴相应用于主动型氢原子频标的锁相环路中,通过参考信号和被锁信号间等效鉴相频率的合理选择,可以做到异频率信号间的直接鉴相并能获得很高的锁相精度.实验结果表明了该设计方案的科学性和先进性,其锁相精度可达10-12/s量级,与传统氢原子频标锁相系统相比具有电路简单,锁相精度高,附加噪声小,可以异频直接锁相等特点,因而在导航定位、空间技术、通讯、计量、精密时频测控等领域获得广泛应用.     

Efficiency of a single-hyperfine-state selector for hydrogen masers

The influence of the beam composition on the long-term stability of the hydrogen maser is considered. A device which removes 85% of the atoms in the undesirable state F = 1 mF = 1, and does not affect the atoms involved in the clock transition, is described. The operating conditions are given.     

Frequency comparison of five commercial cesium standards with a NASA experimental hydrogen maser

Recent long-term phase comparisons between five commercial cesium beam frequency standards and a NASA experimental hydrogen maser, NX-1, have yielded a value for the frequency of the hydrogen maser of 1 420 405 751.7767±0.0024 hertz which is 6.77×10^-12±1.66 lower than that given by Vessot et al. in 1966.     

Large storage box hydrogen maser

An atomic hydrogen maser has been operated that confines atoms in a volume whose linear dimensions are approximately ten times larger than those of previous masers of this type. The uncertainties associated with the wall frequency shift, presently the principal limiting factor in the absolute accuracy of frequency measurements with the hydrogen maser, should be reduced with this device, since the fraction of time an atom spends on the storage box wall is inversely proportional to the diameter of the box. Oscillations are achieved by the use of two resonant cavities coupled by a high-gain amplifier. The strong field maintained in one cavity prestimulates the atoms to radiate at an enhanced rate in the weak field of the other. With enough gain, self-sustained oscillation can be achieved at normal hydrogen fluxes and normal cavityQ-factor values. The theory of the two-cavity large storage box maser is considered and preliminary results are discussed.     

Frequency instability measurement system of cryogenic maser oscillator

The frequency stability measurement of a new kind of secondary frequency standard, the whispering gallery mode maser oscillator, is reported. Based on a very simple design the beatnote comparison with a state-of-the-art cryogenic sapphire resonator oscillator gave a preliminary result of 10^-14 frequency instability at 1 s integration time. The measurement is limited by the microwave synthesis chain used to evaluate the maser stability.     

Frequency stabilized ammonia laser system for probing the 24 THzclock transition of a trapped barium ion

The design, performance and frequency stability of an optically pumped ammonia laser operating on the sP(8,6) transition of ¹⁵NH₃ at 12.48 μm wavelength are discussed. The short term frequency stability was tested by heterodyning two similar lasers. An Allan deviation of 2·10^-11 for averaging times from 10^-4 s to 1 s was achieved for the free running laser. Absolute values of the laser frequency were obtained by measuring against the NRC H4 hydrogen maser standard with the help of the NRC frequency chain. A scan across a narrow fine-structure transition in a single trapped barium ion provided a final test for the overall stability