Achieving traceability to UTC through GNSS measurements

Defraigne, Pascale; Achkar, Joseph; Coleman, Michael J.; Gertsvolf, Marina; Ichikawa, Ryuichi; Levine, Judah; Uhrich, Pierre; Whibberley, Peter; Wouters, Michael J.; Bauch, A.

doi:10.1088/1681-7575/ac98cb

Cited by 8 publications

(3 citation statements)

References 9 publications

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“…for the timing signals generated by GNSS disciplined oscillators. For a demonstration of metrological traceability as proposed in [24], the approach described in this paper and its uncertainties would have to be formally approved under the international conventions. Moreover, the BIPM's insight and verification possibilities on section 4 data is not on a par (and will not be in the foreseeable future) with what is done for section 1 (UTC-UTC(k) values, basis of the Key Comparison 'CCTF-K001.UTC'), which involves constant dialogue and technical information sharing with the operators of UTC(k) timescales.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Monitoring of the offset between UTC and its prediction broadcast by the GNSS

Defraigne,

Pinat,

Petit

et al. 2023

Metrologia

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We present a new approach to report in the Section 4 of BIPM Circular T daily values of the offset between UTC and the predictions of UTC broadcast by the GNSS, this quantity we name bUTC_GNSS. In this approach, the determination of UTC - bUTC_GNSS is based on data collected by several multi-GNSS stations in selected time laboratories worldwide. Test computations over a 7-month period from July 2022 to January 2023 show that the offset between UTC and bUTCGNSS was between 30 and 50 ns for GLONASS, between 5 and 20 ns for BeiDou, and between -5 and +5 ns for GPS and Galileo. We derive the uncertainty on the reported values, which is 4.1 ns for BeiDou and GPS, 3.7 ns for Galileo and 6.6 ns for GLONASS and show that, over the test period, the reported values of UTC-bUTC_GNSS and the solutions obtained from each multi-GNSS station are all consistent within the 1-sigma uncertainties.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Monitoring of the offset between UTC and its prediction broadcast by the GNSS

Defraigne,

Pinat,

Petit

et al. 2023

Metrologia

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“…Those form together with previous papers of this work's authors [23][24][25] the foundation of this report. Based on already available guidelines [26,27] we illustrate in the next section a full scheme for traceable frequency measurements with counters in a calibration laboratory. We choose the GNSS-DO setup, which is often used in industry laboratories, because of the above-mentioned advantage.…”

Section: Introductionmentioning

confidence: 99%

Traceable frequency measurements with counters

Piester,

Staliuniene,

Bauch

2024

Meas. Sci. Technol.

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Received signals from Global Navigation Satellite Systems (GNSS) are nowadays widely used by industry laboratories for ensuring metrological traceability for their respective range of calibration services in the field of time and frequency. Usually, a local frequency standard is steered by continuous GNSS signal reception providing at its output stable and accurate reference signals for the laboratory measurement equipment, in general for synthesizers and counters. Reception of GNSS signals is surely an adequate and practical tool for the purpose, however further steps are needed to establish traceability in a strict metrological sense. Based on already available guidelines and publications, this paper is a contribution to the discussion how metrological traceability to internationally accepted standards can be established in a calibration laboratory. We restrict the discussion to equipment in common use which may not necessarily be of the highest sophistication. In this spirit, we develop a detailed scheme for an uncertainty budget comprising all links of the traceability chain from the device under test to the SI second, the scale-unit of Coordinated Universal Time. Then we go through and apply this scheme step by step to a demonstration setup for frequency measurements with a counter with varying operational parameters. In this framework, a novel approach to distinguish between components of statistical measurement uncertainty is introduced. Furthermore, the limiting uncertainty contributions are discussed and based on a suitable set of parameters an expression for the best measurement capability is given. With this scheme at hand a user may develop an uncertainty budget adapted to his own setup, especially if acceptance from a national accreditation body is sought.

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“…Moreover, in terms of the definition in International Vocabulary in Metrology (VIM) for traceability, the metrology traceability must be acquired through constructing a documented unbroken chain of calibrations, each contributing to the measurement uncertainty. 10 For a standalone GPSDO disciplined by GPS, to achieve the metrology traceability, establishing the unbroken calibration link with UTC is required as described in Defraigne et al, 11 which is the task for the task group of Consultative Committee for Time and Frequency (CCTF) Working Group (WG) on Global Navigation Satellite System (GNSS). Thus, referenced to GPSDO, the traceability of the measurement and evaluation for NTP timing service cannot be declared.…”

Section: Introductionmentioning

confidence: 99%

Performance characterization of network timing with remote traceability via GNSS time transfer

Liang

Yang

Fang

et al. 2023

Measurement and Control

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One credible method for performance evaluation of network timing service was proposed, based on one kind of disciplined time standard with GNSS time transfer, NIMDO. The performance of the NTP timing service were characterized over multiple baselines on both the Internet and the Intranet, and the network delay and the timing offset were analyzed in detail. The results show that on the Internet the averaged timing offsets via the NTP servers are roughly hundreds of μs to several ms level, and on the Intranet the averaged timing offsets via the NTP servers are at about 20 μs level. NTP timing service was mainly affected by white phase noise, and flicker phase noise at the different sites. The maximum change of the timing offset was one-half of the maximum change of RTDelay. The uncertainties have been separately evaluated as less than 30 ms on the Internet and less than 60 μs on the Intranet for NTP timing service.

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Achieving traceability to UTC through GNSS measurements

Cited by 8 publications

References 9 publications

Monitoring of the offset between UTC and its prediction broadcast by the GNSS

Monitoring of the offset between UTC and its prediction broadcast by the GNSS

Traceable frequency measurements with counters

Performance characterization of network timing with remote traceability via GNSS time transfer

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