Studies and possible improvements on the EAL algorithm

Panfilo, G.; Arias, E. F.

doi:10.1109/tuffc.2010.1392

Cited by 16 publications

(19 citation statements)

References 5 publications

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“…The clock readings reported by these laboratories are then combined at the BIPM through an algorithm designed to optimize the frequency stability and accuracy as well as the reliability of the time scale beyond the level of performance that can be realized by any individual clock in the ensemble. The BIPM time department uses an appropriate algorithm [18][19][20][21][22][23][24][25] to generate the international reference UTC each month. The calculation of UTC is carried out in three steps:…”

Section: Utc Calculationmentioning

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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Section: Utc Calculationmentioning

confidence: 99%

The Coordinated Universal Time (UTC)

Panfilo

Arias

2019

Metrologia

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“…In the generation of a time scale, prediction of atomic clock behaviour plays an important role and it is inserted in all time scale algorithms. Many papers have already dealt with the prediction problem (see, for example, references [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]). The method used in this paper is based on the work presented in [2] and concludes the preliminary studies presented in [12,13].…”

Section: Introductionmentioning

confidence: 99%

“…Many papers have already dealt with the prediction problem (see, for example, references [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]). The method used in this paper is based on the work presented in [2] and concludes the preliminary studies presented in [12,13].…”

Section: Introductionmentioning

confidence: 99%

A new prediction algorithm for the generation of International Atomic Time

Panfilo¹,

Harmegnies²,

Tisserand³

2011

Metrologia

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In this paper we present a new prediction algorithm for the generation of International Atomic Time (TAI). The new prediction algorithm takes into account the frequency drift which affects most of the participating atomic clocks. In particular, we focus on the effect of the application of the new model on the prediction term for the frequency drift affecting the free atomic time scale (EAL). We also present its effect on TAI performance and on atomic clock weights.

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“…The most common timescale algorithms are the weighted average and Kalman filtering algorithms, from which some algorithms are modified. The classical weighted average timescale algorithms include ALGOS, which is used by the International Bureau of Weights and Measures (BIPM) [9], and AT1, which is used by the National Institute of Standards and Technology (NIST) [10], both of which include goals of setting up basic timescale equations. With the input of time deviations, the weighted average algorithm optimizes the frequency stability of the synthetic timescale by adjusting the weights of individual clocks.…”

Section: Introductionmentioning

confidence: 99%

Joint Timekeeping of Navigation Satellite Constellation with Inter-Satellite Links

Sun

Huang

Gao

et al. 2020

Sensors

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As a system of ranging and positioning based on time transfer, the timekeeping ability of a navigation satellite constellation is a key factor for accurate positioning and timing services. As the timekeeping performances depend on the frequency stability and predictability of satellite clocks, we propose a method to establish a more stable and predictable space time reference, i.e., inter-satellite link time (ISLT), uniting the satellite clocks through inter-satellite links (ISLs). The joint timekeeping framework is introduced first. Based on the weighted average timescale algorithm, the optimal weights that minimize the increment of the ISLT timescale are determined and allocated to the clock ensemble to improve the frequency stability and predictability in both the long and short term. The time deviations with respect to the system time of nine BeiDou-3 satellites through multi-satellite precise orbit determination (MPOD) are used for joint timekeeping evaluation. According to the Allan deviation, the frequency of the ISLT is more stable than the nine satellite clocks in the short term (averaging time smaller than 7000 s), and its daily stability can reach 6 × 10 −15 . Meanwhile, the short-term (two hours) and long-term (10 h) prediction accuracy of the ISLT is 0.18 and 1.05 ns, respectively, also better than each satellite clock. Furthermore, the joint timekeeping is verified to be robust against single-satellite malfunction.

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Studies and possible improvements on the EAL algorithm

Cited by 16 publications

References 5 publications

The Coordinated Universal Time (UTC)

The Coordinated Universal Time (UTC)

A new prediction algorithm for the generation of International Atomic Time

Joint Timekeeping of Navigation Satellite Constellation with Inter-Satellite Links

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