An Efficient and Configurable Preprocessing Algorithm to Improve Stability Analysis

Sesia, I.; Cantoni, E.; Cernigliaro, A.; Signorile, G.; Fantino, G.; Tavella, P.

doi:10.1109/tuffc.2015.2496280

Cited by 20 publications

(14 citation statements)

References 11 publications

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“…To assess the accuracy contribution of the fiber link during a clock comparison campaign, we face the difficulty of handling with irregular and non continuous data with gaps [32]. Here we follow a rigorous method based on the noise model fitting.…”

Section: Resultsmentioning

confidence: 99%

Reciprocity of propagation in optical fiber links demonstrated to 10⁻²¹

Xu¹,

Delva²,

Lopez³

et al. 2019

Opt. Express

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We present a study of the fundamental limit of fiber links using dedicated link architecture. We use an experimental arrangement that enables us to detect the forward and backward propagation noise independently and simultaneously in optical fiber and where the optical phase evolution is expected to be driven by the only contribution of the reference arms of the Michelson interferometer ensemble. In this article, we demonstrate indeed the high correlation between the optical phase evolution and the temperature variation of the interferometer ensemble, leading to a frequency offset of (4.4 ± 2.3) × 10 −21 . Using a simple temperature model and a Bayesian analysis to evaluate the model parameters, we show that the temperature effect can be compensated with post-processing, removing the frequency offset down to (0.5 ± 2.0) × 10 −21 . The residual slope of the optical phase evolution over 33 days is 350 yoctosecond/s. Using a global temperature parameter, we divide these 33 days dataset in four subsets and analyse their uncertainties. We show that they are self-consistent when the temperature is taken into account. This provides an alternative method to evaluate the accuracy of a fiber link, especially when the dataset includes large dead times. The result is finally interpreted as a test of the reciprocity of the propagation delay in an optical fiber. This unprecedented transfer capability could enable the comparisons of future optical clocks with expected performance at 10 −20 level and open new possibilities for stringent tests of special and general relativity.

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Section: Resultsmentioning

confidence: 99%

Reciprocity of propagation in optical fiber links demonstrated to 10⁻²¹

Xu¹,

Delva²,

Lopez³

et al. 2019

Opt. Express

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“…Second, to obtain the frequency offset data that we will analyze in the frequency and time-frequency domains after the preprocessing operations described in the subsequent steps, we follow the standard definition (see, for example, Kartaschoff (1978)) and differentiate the phase offset data with a sampling time T s = 300 s. Note that the differentiation process translates the random walk noise affecting the phase data into a white frequency noise, and the observed day-boundary phase jumps, resulting from the data processing applied by the analysis centers generating the clock products, into frequency outliers. Third, we filter out these and the other possible frequency outliers according to the approach described in Sesia et al (2016). Fourth, we estimate the time-varying mean ̂ (t) of the frequency offset y(t) by sliding a window made by N W = 169 samples.…”

Section: Frequency and Time-frequency Analysis Of The Galileo Satellimentioning

confidence: 99%

Time–frequency analysis of the Galileo satellite clocks: looking for the J2 relativistic effect and other periodic variations

Formichella¹,

Galleani

Signorile³

et al. 2021

GPS Solut

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When observed from the ground, the frequency of the atomic clocks flying on the satellites of a Global Navigation Satellite System is referred to as apparent frequency, because it is observed through the on-board signal generation chain, the propagation path, the relativistic effects, the measurement system, and the clock estimation algorithm. As a consequence, the apparent clock frequency is affected by periodic variations of different origins such as, for example, the periodic component of the J2 relativistic effect, due to the oblateness of the earth, and the clock estimation errors induced by the orbital estimation errors. We present a detailed characterization of the periodic variations affecting the apparent frequency of the Galileo clocks, obtained by applying time–frequency analysis and other signal processing techniques on space clock data provided by the European Space Agency. In particular, we analyze one year of data from three Galileo Passive Hydrogen Masers, flying on two different orbital planes. Time–frequency analysis reveals how the spectral components of the apparent frequency change with time. For example, it confirms that the amplitude of the periodic signal due to the orbital estimation errors depends on the angle between the sun and the orbital plane. Moreover, it allows to find a more precise estimate of the amplitude of the J2 effect, in agreement with the prediction of the general theory of relativity, and it shows that such amplitude suddenly decreases when the corresponding relativistic correction is applied to the data, thus validating the analytical formula used for the correction.

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“…(1) should be taken as a reasonable value that is not rigorously justified by reference to the probabilities derived for a Gaussian distribution. This test is commonly used in the literature [18,19], even for data that do not satisfy a Gaussian distribution. As a specific example, assume that the time difference in Eq.…”

Section: Synchronization Algorithmmentioning

confidence: 99%

“…In the second place, again in contrast to the previous discussion, there is no a priori estimate for the magnitude of the TDEV based on considerations outside of the measurement process. Finally, the outlier algorithm must function in a realtime environment, and methods that depend on a postprocessed batch analysis of a large quantity of data, such as the calculation of the median, or methods that depend on several passes through the data [18,19] either cannot be used at all or depend on too many computer cycles to be practical. (The median and the average are not significantly different when the number of outliers is less than 1 % as in the data in this study; see Fig.…”

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confidence: 99%

See 1 more Smart Citation

The Statistics of Computer Clocks and the Design of Synchronization Algorithms

Levine

2020

J. RES. NATL. INST. STAN.

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In this study, I used standard statistical tools (such as the various forms of the two-sample Allan variance) to characterize the clocks in computers, and I show how the results of this study are used to design algorithms to synchronize the computer clocks. These synchronization algorithms can be used to synchronize the time of a computer to a local reference clock or to a remote server. The algorithms by themselves are not intended to be a simple replacement for software that implements the Network Time Protocol (NTP) or any other similar application. Instead, they describe the statistical principles that should be used to design an algorithm to synchronize any computer clock by using data from any external reference received in any format. These algorithms have been used to synchronize the clocks of the computers that support the Internet Time Service operated by the National Institute of Standards and Technology (NIST), and I illustrate the performance of the algorithm with real-time data from these servers. In addition to presenting the design principles of the algorithm, I illustrate the principles with two specific examples: synchronizing a computer clock to a local reference signal, and the design of a synchronization process that is based on time-difference data received from a remote server over the public Internet. The message exchange between the local system and the remote server in this configuration is realized in NTP format, but that is not a fundamental requirement.

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An Efficient and Configurable Preprocessing Algorithm to Improve Stability Analysis

Cited by 20 publications

References 11 publications

Reciprocity of propagation in optical fiber links demonstrated to 10⁻²¹

Reciprocity of propagation in optical fiber links demonstrated to 10⁻²¹

Time–frequency analysis of the Galileo satellite clocks: looking for the J2 relativistic effect and other periodic variations

The Statistics of Computer Clocks and the Design of Synchronization Algorithms

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An Efficient and Configurable Preprocessing Algorithm to Improve Stability Analysis

Cited by 20 publications

References 11 publications

Reciprocity of propagation in optical fiber links demonstrated to 10−21

Reciprocity of propagation in optical fiber links demonstrated to 10−21

Time–frequency analysis of the Galileo satellite clocks: looking for the J2 relativistic effect and other periodic variations

The Statistics of Computer Clocks and the Design of Synchronization Algorithms

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Product

Resources

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Reciprocity of propagation in optical fiber links demonstrated to 10⁻²¹

Reciprocity of propagation in optical fiber links demonstrated to 10⁻²¹