Fidelity - Progress Report on Delivering the Prototype Galileo Time Service Provider

Achkar, Joseph; Tuckey, Philip; Ullrich, P.; Valat, David; Batchelor, A. J.; Burden, G.; Bauch, A.; Piester, D.; Cordara, F.; Tavella, P.; Davis, John; Delporte, J.; Jones, Richard H.; Levin, Todd; Staton, G.; Nawrocki, Jerzy

doi:10.1109/freq.2007.4319114

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…Within Europe, the EGNOS GNSS augmentation system is traceable to UTC through UTC(OP) (Delporte et al 2009). The European Galileo system is considering a somewhat different approach based on a Time Service Provider that would combine the UTC(k) time scales of four or more European national laboratories (Achkar et al 2007).…”

Section: Linkage Of Gnss Time Scales To Utcmentioning

confidence: 99%

Local representations of UTC in national laboratories

2011

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Local representations of the international time scale, Coordinated Universal Time (UTC), are maintained by approximately 69 national measurement institutes and other time laboratories. These laboratories contribute their clock and time transfer measurements for use in the computation of UTC. Although local representations of UTC, commonly called UTC(k) time scales, vary considerably, for example in the numbers of atomic clocks available, they also share many characteristics. In this paper, we examine the rationale and requirements for maintaining a local representation of UTC. Its applications might range from underpinning the reference time scale of a Global Navigation Satellite System to providing traceability for frequency and time dissemination services. We address the practical aspects of setting up and operating a UTC(k) time scale, including the equipment and algorithms that generate the time scale, optimize its performance and measure its offset from the similar time scales maintained by other laboratories. We conclude by considering briefly some future developments that may have an impact on the laboratories operating local representations of UTC.

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Section: Linkage Of Gnss Time Scales To Utcmentioning

confidence: 99%

Local representations of UTC in national laboratories

2011

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“…This is of even more relevance as UTC(PTB) shall be used as one of the time references for the generation or validation of the Galileo System Time (GST) of the European satellite navigation system Galileo [17]. The timing system is at the heart of every navigation system.…”

Section: Time Scale Predictionmentioning

confidence: 99%

“…To give an example, PTB stated a few years ago that {UTC−UTC(PTB)} could be predicted with 40 ns uncertainty (95% confidence) 20 days after the last published value in Circular T. Inspection of figure 7 reveals that this capability has been substantially improved after the new realization scheme was implemented. This is of even more relevance as UTC(PTB) shall be used as one of the time references for the generation or validation of the Galileo System Time (GST) of the European satellite navigation system Galileo [17]. The timing system is at the heart of every navigation system.…”

Section: Time-scale Predictionmentioning

confidence: 99%

Generation of UTC(PTB) as a fountain-clock based time scale

et al. 2012

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The Physikalisch-Technische Bundesanstalt (PTB) has substantially improved the quality of its local time scale UTC(PTB), which is the national realization of the international time reference Coordinated Universal Time (UTC). It serves as basis for PTB's time services, for local clock comparisons and for international time comparisons. Since February 2010 UTC(PTB) has been realized using an active hydrogen maser (AHM) steered in frequency via a phase micro stepper according to an algorithm which combines the frequency comparison data between the AHM and primary and commercial caesium clocks of PTB. Thereby the long-term stability and accuracy of PTB's primary clocks, in particular its fountain clock CSF1, were combined with the short-term frequency stability of the AHM. CSF1 data were used to calculate the steering on all days except of 6 days during 15 months. During the time between July 2010 and July 2011, the time difference between UTC(PTB) and UTC was always less than 6 ns and the monthly mean rate differences never exceeded 0.16 ns/day.

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“…The considerations here concern only the numbering of seconds of the GST and not other characteristics of GST. Already at the very beginning of the Galileo project, it was decided that GST would fulfil all international recommendations [13,14] except that, in the same way as GPS time, it should be a continuous time without leap seconds.…”

Section: Galileo System Time (Gst)mentioning

confidence: 99%

GNSS times and UTC

Lewandowski

Arias

2011

Metrologia

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Global Navigation Satellite Systems (GNSSs) use internal reference time scales: GPS Time, GLONASS Time, Galileo System Time and BeiDou System Time. Constructed from a clock ensemble, they are designed for internal system synchronization, necessary to produce a navigation solution. They are usually steered to an external stable reference time scale, for example UTC(USNO), modulo 1 s, for GPS time. To achieve safe operation of a GNSS, a system time should preferably be a uniform time scale not affected by the leap seconds of Coordinated Universal Time (UTC). But this is not compatible with international recommendations that radio broadcast time signals should conform as closely as possible to UTC. This paper describes the various approaches chosen by GNSS providers and the relation between GNSS system times and UTC in terms of numbering of seconds. Different solutions for numbering seconds do not help the GNSS interoperability. This paper also explains why, on some occasions, GNSS system times play a role of alternative time scales with the consequent risk of confusion.

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Fidelity - Progress Report on Delivering the Prototype Galileo Time Service Provider

Cited by 7 publications

References 5 publications

Local representations of UTC in national laboratories

Local representations of UTC in national laboratories

Generation of UTC(PTB) as a fountain-clock based time scale

GNSS times and UTC

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