Comparison between frequency standards in Europe and the USA at the 10-15 uncertainty level
Comparison between frequency standards in Europe and the USA at the 10-15 uncertainty level
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DOI：
10.1088/0026-1394/43/1/016
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发表时间：
2006-02-01
期刊：
影响因子：
2.4
通讯作者：
Uhrich, P
中科院分区：
文献类型：
--
作者：
Bauch, A;Achkar, J;Uhrich, P
国家伽利略法拉利电子技术研究所（IEN）、国家标准与技术研究所（NIST）、国家物理实验室（NPL）、国家计量实验室和巴黎天文台/参考温度系统（OP）和德国物理技术实验室（PTB）运行基于冷原子的主频标准，能够实现SI秒的相对不确定度为1 × 10（-15）甚至更低。这些研究所在2004年10月/ 11月约25天内对其实验室中保存的选定频率参考文献进行了激烈的比较。活性氢脉泽参考标准作为各研究所喷泉频率标准的频率参考。采用了三种频率（和时间）比较技术。双向卫星时间和频率传输（TWSTFT）在每天12次等间隔测量的强化测量计划中进行。对双频全球定位系统（GPS）接收器的数据进行处理，得到两个GPS频率的代码观测的无电离层线性组合，通常称为GPS TAI P3分析。最后但并非最不重要的是，同样的GPS原始数据被单独处理，允许基于GPS载波相位（GPS CP）的频率比较。在所有方法中，这些方法在短平均时间内的相对频率不稳定性最低。使用TWSTFT和GPS CP在一天平均时间内，不稳定性处于1015年的1分之一水平。GPS TAI P3分析在平均两天或更长时间后能够提供类似质量的数据。所有技术在10（16）中少数部分的1西格玛测量不确定度范围内提供了相同的标准之间的平均频率差。评价IEN （IEN- csf1）、NPL （NPL- csf1）和OP （OP- fo2）三个喷泉的频率差异。NPL和OP之间的测量不确定度差异小于1，而IEN喷泉与其他两个喷泉相差约2西格玛。
Istituto Elettrotecnico Nazionale Galileo Ferraris (IEN), National Institute of Standards and Technology (NIST), National Physical Laboratory (NPL), Laboratoire National de Metrologie et d'Essais-Observatoire de Paris/Systemes de Reference Temps Espace (OP) and Physikalisch-Technische Bundesanstalt (PTB) operate cold-atom based primary frequency standards which are capable of realizing the SI second with a relative uncertainty of 1 x 10(-15) or even below. These institutes performed an intense comparison campaign of selected frequency references maintained in their laboratories during about 25 days in October/November 2004. Active hydrogen maser reference standards served as frequency references for the institutes' fountain frequency standards. Three techniques of frequency (and time) comparisons were employed. Two-way satellite time and frequency transfer (TWSTFT) was performed in an intensified measurement schedule of 12 equally spaced measurements per day. The data of dual-frequency geodetic Global Positioning System (GPS) receivers were processed to yield an ionosphere-free linear combination of the code observations from both GPS frequencies, typically referred to as GPS TAI P3 analysis. Last but not least, the same GPS raw data were separately processed, allowing GPS carrier-phase (GPS CP) based frequency comparisons to be made. These showed the lowest relative frequency instability at short averaging times of all the methods. The instability was at the level of I part in 1015 at one-day averaging time using TWSTFT and GPS CP. The GPS TAI P3 analysis is capable of giving a similar quality of data after averaging over two days or longer. All techniques provided the same mean frequency difference between the standards involved within the 1 sigma measurement uncertainty of a few parts in 10(16). The frequency differences between the three fountains of IEN (IEN-CsF1), NPL (NPL-CsF1) and OP (OP-FO2) were evaluated. Differences lower than the I a measurement uncertainty were observed between NPL and OP, whereas the IEN fountain deviated by about 2 sigma from the other two fountains.