一种高准确度频标比对方法

本文利用频标信号之间的最大公因子频率和等效鉴相频率的概念,并将等效鉴相频率特性应用到频标比对上,提出了一种新的频标比对方法,基于这种新的比对方法,给出在相位比较法基础上发展的数字实现方法,实际工作情况证明,采用这种新的频标比对方法具有电路简单,可靠性高的优点,并且比以往的测量方法具有更高的测量准确度。     

频标比对测量中的数据处理方法研究

没有准确度等级更高的标准(参考源)，准确度等级相同的三台频标互比，测量其各自的日频率稳定度(均方根值)和日频率波动，这种测试和计算方法有数理统计学的根据，它的应用促进了技术创新。     

TV-Rb频标

1987年,我国中央电视台开始在电视信号中播发标准时间和标准频率[1],用户可以很方便地通过接收电视信号来获得标准时间和标准频率。我们利用中央电视台播发的彩色电视副载波443ＭＨｚ标准频率去锁定一台Ｒｂ原子频标(以下简称ＴＶＲｂ频标),获得了准确度、长期稳定度和短期稳定度均极佳的结果。近年来,社会上已有用中央电视台播发的彩色电视副载波去锁定晶振的产品出售,但由于从电视机取出的彩色电视副载波的短期稳定度不好,所以这类产品的短稳一般也不好,在1×10-9/ｓ左右。另外由于彩色副载波经常发生跳相,所以这类产品的输出也存在跳相,…     

关于频标比对器检定规程中有关问题的讨论

1 问题的提出 JJG545-88<频标比对器检定规程>是目前现行通用的规程,它的适用对象是新制造的、使用中的和修理后的PO7系列频标比对器. 笔者对于规程中的带宽检定方法以及带宽计算公式存有疑问.为方便说明问题,现将JJG545-88检定规程中有关测量带宽的检定方法和计算公式转述如下:     

中俄标准水听器在0.01Hz～1Hz频段的双边比对校准

本文叙述了中国杭州应用声学研究所与俄罗斯全俄物理技术与无线电测量科学研究院的标准水听器在0.01Hz～1Hz频率范围内的双边比对校准.通过俄方水听器在中方实验室的比对校准、中方水听器在俄方实验室的比对校准以及中俄双方专家的讨论三个阶段的工作,比对达到了令人满意的结果.     

咨询委员会关键比对导则

咨询委员会关键比对导则Ｔ．Ｊ．Ｑｕｉｎｎ起草于１９９８年５月１．引言关键比对由咨询委员会（ＣＣ）选择、实施和评定。ＣＣ所采用程序（包括比对的详细技术方案和比对周期）的设计应确保：●比对所需的测试涉及相应领域的一切主要技术；●比对结果清楚而明确；●比对...     

实用超高真空比对校准系统

介绍了一种实用超高真空相对比对校准系统。该装置具有结构简单、实用、不确定度小等优点,可以满足在10^-7～10^-5Pa范围内超高真空规的比对校准。     

中俄标准水听器在0.01～1Hz频段的双边比对校准

叙述中国杭州应用声学研究所和俄罗斯全俄物理技术与无线电测量科学研究院的标准水听器在0．01～1Hz频率范围内的双边比对校准方法和结果。在15个频率点上双方分别对5个不同水听器测得的开路电压灵敏度之差的平均值最小为0．02dB,最大也只有0．21dB,远小于双方合成的总扩展不确定度,这证明了两国在此频段内的水声声压标准装置都有很高的准确度。     

实验室型频标准确度国际专题讨论会

1991年3月10～11日在法国贝藏松(Besancon)召开了一次实验室型频标准确度国际专题讨论会。此次讨论会是由法国国家计量局时间频率基准实验室的M.Granveaud和A.Clairon以及意大利都灵工业大学教授A.De Marchi三人发起,由欧共体资助的。出席会议的有法、美、英、中、苏、德、日、意、加、瑞士等10个国家的30位学者,包括新任国际计量局时频处处长C.Thomas女士。 如所周知,频率基准是当今国际上最准确的计量基准,其准确度比其它物理量的基准要高出4、5个数量级,因此,长度及一些电磁量单位已由频率导出,并有进一步使各种计量     

两种计量比对

提出了两种计量比对的概念,即量值比对和检定/校准比对。并对两种比对的目的、特点进行了论述,对国内正在进行的各种计量比对有相当的参考价值。     

Results of Comparisons of the Working Standards of Frequency Deviation

The results of comparisons of six working standards of frequency deviation, carried out using a new comparator, are considered.     

An Optical Frequency Comb Tied to GPS for Laser Frequency/Wavelength Calibration

Optical frequency combs can be employed over a broad spectral range to calibrate laser frequency or vacuum wavelength. This article describes procedures and techniques utilized in the Precision Engineering Division of NIST (National Institute of Standards and Technology) for comb-based calibration of laser wavelength, including a discussion of ancillary measurements such as determining the mode order. The underlying purpose of these calibrations is to provide traceable standards in support of length measurement. The relative uncertainty needed to fulfill this goal is typically 10⁻⁸ and never below 10⁻¹², very modest requirements compared to the capabilities of comb-based frequency metrology. In this accuracy range the Global Positioning System (GPS) serves as an excellent frequency reference that can provide the traceable underpinning of the measurement. This article describes techniques that can be used to completely characterize measurement errors in a GPS-based comb system and thus achieve full confidence in measurement results.     

提高低温电流比较仪测量准确度的几方面措施

通过对低温电流比较仪系统及运行过程的研究，发现了氦气气压波动、冻结磁通引起的附加噪声以及线圈匝数增多时分布电容引起的电流跳跃是限制系统不确定度停留在10^-9量级而不能进一步提高的原因。提出了一种新型的气压滤波器滤除了附加噪声。还改进了电路动态特性，改善了前馈补偿环节，把匝数比提高了5倍。运行过程中的电流跳跃现象也被消除。采用这些措施后，信噪比提高了5倍，新建的低温电流比较仪的测量准确度提高到了10^-10量级。     

关于离子阱频标

本文介绍了离子阱频标的原理、现状及前景，并给出了该频标与实验室型磁选态铯束频标，光抽运铯束频标及铯原子喷泉频标的性能比较。     

电流比较仪在大电容测量中的应用

介绍了电流比较仪的基本原理和几种常见电流比较仪式电容电桥,并重点介绍了模拟大电容的组成原理及测量模拟大电容用的电流比较仪电桥,同时就测量大电容需要注意的事项,给出了简单的说明。     

Primary Atomic Frequency Standards at NIST

The development of atomic frequency standards at NIST is discussed and three of the key frequency-standard technologies of the current era are described. For each of these technologies, the most recent NIST implementation of the particular type of standard is described in greater detail. The best relative standard uncertainty achieved to date for a NIST frequency standard is 1.5×10⁻¹⁵. The uncertainties of the most recent NIST standards are displayed relative to the uncertainties of atomic frequency standards of several other countries.     

Analysis and Synthesis of a Flip-Flop Comparator

A method of constructing flip-flops with structures that are optimized for use in comparators is considered. The method enables the reliability with which the result of a comparison of flip-flop comparators is stored to be increased.     

直流大电流比较仪谐波影响问题的研究

本提出了在谐波影响下直流大电流比较仪的等效电路模型及计算方法,通过仿真给出了该模型的频率特性,通过试验数据与仿真结果的比较证实了电路模型的可行性,对研究直流大电流比较仪和电流互感器的谐波影响具有指导意义。     

A Time-Domain Comparator Based Skipping-Window SAR ADC

This paper presents an energy efficient successive-approximation register (SAR) analog-to-digital converter (ADC) for low-power applications. To improve the overall energy-efficiency, a skipping-window technique is used to bypass corresponding conversion steps when the input falls in a window indicated by a time-domain comparator, which can provide not only the polarity of the input, but also the amount information of the input. The time-domain comparator, which is based on the edge pursing principle, consists of delay cells, two NAND gates, two D-flip-flop register-based phase detectors and a counter. The digital characteristic of the comparator makes the design more flexible, and the comparator can achieve noise and power optimization automatically by simply adjusting the delay cell number. An energy efficient digital-to-analog converter (DAC) control scheme suitable for the skipping window technique is also developed to reduce the switching energy during SAR conversion. Together with the skipping-window technique, the linearity and the power consumption of the SAR ADC are improved. The impact of different window sizes on comparison cycles, DAC switching energy and the overall energy efficiency is analyzed. Simulation results show that the proposed skipping-window technique can improve the overall energy-efficiency of the SAR ADC, as well as the linearity, and the optimized window size for the overall energy efficiency will vary with the DAC switching energy.     

The special state standard of the unit of frequency deviation

The main characteristics of a new special state standard of the unit of frequency deviation are described.Translated from Izmeritelnaya Tekhnika, No. 1, pp. 36–39, January, 2005.