Robust clock ensemble for time and frequency reference system

Wang, Qinghua; Droz, Fabien; Rochat, P.

doi:10.1109/fcs.2015.7138861

Cited by 9 publications

(4 citation statements)

References 1 publication

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“…Fault detection in clock ensembles is further discussed in [23][24][25] using Kalman filters. Instead, the methods in [26][27][28] use least-squares fitting, standard deviation computed on sliding windows, and infinite impulse response filters.…”

Section: State Of the Artmentioning

confidence: 99%

Detection and identification of faults in clock ensembles with the generalized likelihood ratio test

2022

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In this paper we propose an approach for performing fault detection and identification in clock ensembles based on the generalized likelihood ratio test. We show that by applying a set of purposefully-designed statistical tests, one can successfully detect faults occurring in a clock of the ensemble, and identify which measurement in the ensemble is most likely to have triggered the detection. We first develop the theoretical framework for the characterization of the detectors and their performance, and validate the derivations via Monte Carlo simulations. Then, we apply the statistical tests to an ensemble of cesium clocks, aiming at detecting and identifying three types of non-nominal behaviors. The faulty conditions are obtained by injecting a pattern of phase steps, a phase and frequency drift, and an oscillatory phase component.

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Section: State Of the Artmentioning

confidence: 99%

Detection and identification of faults in clock ensembles with the generalized likelihood ratio test

2022

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“…The results and experiences gathered for an onboard timing system led us to propose a Robust Clock Ensemble (RCE) solution for the next generation of PTF, which aims to integrate time generation as well as measurement and control subsystems (Wang et al, 2015). The ONCLE-based solution aims to improve the performance of GST, real-time clock anomaly detection, and automatic fault compensation (or clock switch-over).…”

Section: Proposal Of Robust Clock Ensemble For Next Generationmentioning

confidence: 99%

ONCLE (One Clock Ensemble) for Galileo’s Next-Generation Robust Timing System

Wang¹,

Rochat²

2022

navi

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The generation of the clock ensemble output (or timescale), based on a pool of clocks that shows better performance in terms of accuracy, stability and reliability, is a concept that has been successfully implemented over many years. The fundamental concept of the timescale is the weighted average of the N clocks to optimize the ensemble performance with regard to different individual clock performances (Brown, 1991;Stein, 2003;Thomas et al., 1994).To improve the robustness of the timing system, the identification of clock anomalous behavior has been of great interest. There is a large body of technical literature on detecting discontinuities in time series using various methods based on sliding square windows and Kalman filters (

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“…[6][7][8] Usually, the noise characteristics of different atomic clocks are assumed to be independent of each other. [9][10][11] With the increasing demand for high-precision time services, this assumption should be carefully reconsidered and revised.…”

Section: Introductionmentioning

confidence: 99%

A redundant subspace weighting procedure for clock ensemble

Xu 徐,

Chen 陈,

Liu 刘

et al. 2024

Chinese Phys. B

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A redundant-subspace-weighting (RSW) based approach is proposed to enhance the frequency stability of the time scale of a clock ensemble. In this approach, multiple overlapping subspaces are constructed in the clock ensemble, and the weight attributed to each clock in this ensemble is defined using the spatial covariance matrix. Superimposition averaging of different subspace covariances somewhat reduces the correlations between clocks located in the same laboratory. After optimizing the parameters of this weighting procedure, the frequency stabilities of virtual clock ensembles are significantly improved in most cases.

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Robust clock ensemble for time and frequency reference system

Cited by 9 publications

References 1 publication

Detection and identification of faults in clock ensembles with the generalized likelihood ratio test

Detection and identification of faults in clock ensembles with the generalized likelihood ratio test

ONCLE (One Clock Ensemble) for Galileo’s Next-Generation Robust Timing System

A redundant subspace weighting procedure for clock ensemble

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