共查询到20条相似文献,搜索用时 109 毫秒
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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。 相似文献
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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: 相似文献
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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... 相似文献
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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。 相似文献
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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。 相似文献
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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 相似文献
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A. V. Myl'nikov 《Measurement Techniques》2003,46(6):612-615
The results of comparisons of six working standards of frequency deviation, carried out using a new comparator, are considered. 相似文献
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Jack A. Stone Patrick Egan 《Journal of research of the National Institute of Standards and Technology》2010,115(6):413-431
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. 相似文献
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D. B. Sullivan J. C. Bergquist J. J. Bollinger R. E. Drullinger W. M. Itano S. R. Jefferts W. D. Lee D. Meekhof T. E. Parker F. L. Walls D. J. Wineland 《Journal of research of the National Institute of Standards and Technology》2001,106(1):47-63
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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献