Calibration of the IEN-PTB TWSTFT link with a portable reference station

Cordara, F.; Lorini, L.; Pettiti, V.; Tavella, P.; Piester, D.; Becker, Juergen; Polewka, T.; Jong, Gerrit de; Koudelka, Otto; Ressler, H.; Blanzano, B.; Karel, C.

doi:10.1049/cp:20040833

Cited by 8 publications

(8 citation statements)

References 3 publications

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“…In Figure 5, the CCD measurements together with the mean and SD values are shown. The standard deviations (SD) varied between 0.2 ns and 0.7 ns, which is a typical data scatter range also observed in the other European campaigns E2 -E3 [16,17]. We have currently no explanation why the pattern of the individual data is so different between sites, but it was found to be to some extent reproducible [16,17,18].…”

Section: Results Obtained During the Campaignmentioning

confidence: 73%

“…Reference E1 1997 TUG, DTAG, PTB [9] T1 2002 USNO, PTB [11] T2 2003 USNO, PTB [13] E2 2003 IEN, PTB [16] E3 2004 PTB, VSL, OP, NPL [17] T3 2004 USNO, PTB [14] T4 2004 USNO, PTB [14] T5 2005 USNO, PTB [14] E4 2005 PTB, SP, VSL, NPL, OP, INRIM [18] T6 2006 USNO, PTB [15] E5 2006 TUG, PTB, METAS [19] T7 2007 USNO, PTB -T8 2007 USNO, PTB -…”

Section: No Year Participating Institutesmentioning

confidence: 99%

“…The last exercise took part in November 2007. During the last few years, several European TWSTFT links, namely these between INRIM, METAS, NPL, OP, PTB, SP, the Technical University of Graz (TUG) in Austria, and VSL, were calibrated by means of TWSTFT employing the portable station of TUG [16,17,18,19] . The link calibration campaigns carried out up to now are listed in Table 1.…”

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confidence: 99%

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Time transfer with nanosecond accuracy for the realization of International Atomic Time

et al. 2008

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Two-way satellite time and frequency transfer (TWSTFT) has become an important technical component in the process of the realization of International Atomic Time. To employ the full potential of the technique, especially for true time transfer, a dedicated calibration is necessary. This consists of the calibration either of the operational link at large, including every component involved, or of the involved ground stations' internal delays only. Both modes were successfully employed by circulating and operating a portable reference station between the sites involved. In this paper, we summarize the theoretical background for the different calibration modes applied and report examples of results from the 13 calibration campaigns performed up to now in Europe and between Europe and the United States. In all of these exercises, estimated uncertainties around 1 ns were achieved. Consecutive campaigns showed a very good reproducibility at the nanosecond level. Additionally, we address and briefly discuss sources that possibly limit the uncertainty for true time transfer employing TWSTFT.

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Section: Results Obtained During the Campaignmentioning

confidence: 73%

Section: No Year Participating Institutesmentioning

confidence: 99%

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confidence: 99%

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Time transfer with nanosecond accuracy for the realization of International Atomic Time

et al. 2008

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“…These uncertainty components are also valid for the TWSTFT links, with values representing the quality of the measurement and the stability of the hardware. But the calibration of the TWSTFT links is different; the laboratories organize calibrations of their TWSTFT equipment with the support of the BIPM and of the CCTF Working Group on TWSTFT [61][62][63][64]. The operational aspects of a TWSTFT calibration campaign are described in the document 'TWSTFT calibration guidelines for UTC time links' [65].…”

Section: Characterization Of the Relative Delay Of Time-transfer Equi...mentioning

confidence: 99%

The Coordinated Universal Time (UTC)

Panfilo

Arias

2019

Metrologia

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Coordinated Universal Time (UTC) has considerably changed in recent years. The evolution of UTC follows the scientific and industrial progress by developing appropriate models, more adapted calculation algorithms, more efficient and rapid dissemination processes and a well defined traceability chain. The enormous technical progress worldwide has resulted in an impressive number of atomic clocks now available for UTC calculation. The refined time and frequency transfer techniques are approaching the accuracy requested for the new definition of the SI second. The more regular operation of primary frequency standards (PFS) increases the accuracy of UTC and opens a possible new development for time scale algorithms. From the metrological point of view all the ingredients are available for major improvements to UTC. Dissemination of UTC is done by the monthly publication of results in BIPM Circular T. This document makes a quality evaluation of local representations of UTC, named UTC(k), in national institutes, and other organizations, by giving the evolution of their offsets relative to UTC and their respective uncertainties. The clock models adopted and the time transfer techniques have progressively improved over the years, assuring the long-term stability of UTC. Each computation of UTC processes data over one month with five-day sampling and publication. A rapid solution of UTC (UTCr) has existed since 2013, and consists of the processing of daily sampled data over four consecutive weeks, computed and published weekly. It gives quick access to UTC, and allows participating laboratories to better monitor the offsets of their realizations to the reference UTC. The traditional monthly publication, containing results of all the laboratories contributing data to the BIPM for the computation of UTC was complemented after the establishment of the Mutual Recognition Arrangement of the International Committee on Weights and Measures (CIPM MRA). This time comparison, which has been the responsibility of the BIPM since 1988, added as a complement the key comparison on time defined by the Consultative Committee for Time and Frequency (CCTF) in 2006 as CCTF-K001.UTC, where the results published are those of national metrology institutes (NMIs) signatories of the CIPM MRA, or designated institutes (DIs). The traceability issues are formalized in the framework of the CIPM MRA. The development of time metrology activities in the different metrology regions, supports the actions of the BIPM time department to improve the accuracy of [UTC–UTC(k)], where the coordination with the Regional Metrology Organizations (RMOs) has a key role. This paper presents an overview of UTC.

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“…Successive campaigns with BIPM travelling receivers have been carried out since 2001 with the result that more than 50% of the GPS receiver equipment used in TAI has been calibrated (Petit et al 2001;Lewandowski & Moussay 2002, 2003aLewandowski & Tisserand 2004a,b,c). The situation for the TWSTFT links is rather different; the laboratories organize, with the support of the BIPM, calibrations of the TWSTFT equipment (Matsakis 2003;Cordara et al 2004;Piester et al in press). In the case of links between non-calibrated TW stations, a calibration by using the corresponding GPS receiver backup link is introduced to include them in the calculation of TAI.…”

Section: (I) Use Of Gps Receiver For Time Transfermentioning

confidence: 99%

The metrology of time

Arias

2005

Phil. Trans. R. Soc. A.

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Measuring time is a continuous activity, an international and restless enterprise hidden in time laboratories spread all over the planet. The Bureau International des Poids et Mesures is charged with coordinating activities for international timekeeping and it makes use of the world's capacity to produce a remarkably stable and accurate reference time-scale. Commercial atomic clocks beating the second in national laboratories can reach a stability of one part in 10(14) over a 5 day averaging time, compelling us to research the most highly performing methods of remote clock comparison. The unit of the international time-scale is the second of the International System of Units, realized with an uncertainty of the order 10(-15) by caesium fountains. Physicists in a few time laboratories are making efforts to gain one order of magnitude in the uncertainty of the realization of the second, and more refined techniques of time and frequency transfer are in development to accompany this progress. Femtosecond comb technology will most probably contribute in the near future to enhance the definition of the second with the incorporation of optical clocks. We will explain the evolution of the measuring of time, current state-of-the-art measures and future challenges.

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Calibration of the IEN-PTB TWSTFT link with a portable reference station

Cited by 8 publications

References 3 publications

Time transfer with nanosecond accuracy for the realization of International Atomic Time

Time transfer with nanosecond accuracy for the realization of International Atomic Time

The Coordinated Universal Time (UTC)

The metrology of time

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