Amelioration of the usage and Monitoring of GNSS Signals at PTB

Bauch, A.; Piester, D.; Polewka, T.; Staliuniene, Egle

doi:10.33012/2019.16747

Cited by 2 publications

(5 citation statements)

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“…Today the US global positioning system (GPS) is widely used in combination with Galileo and/ or Glonass for this purpose. In this case, the question of traceability to UTC remains under debate [4,5]. Maybe even more important seems the fact that jamming/spoofing of satellite signals remains a continuous threat that is out of control of a telecom operator [6].…”

Section: Telecommunication Union-telecommunication Sector (Itu-t)mentioning

confidence: 99%

Calibrated optical time transfer of UTC(k) for supervision of telecom networks

et al. 2018

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We report on the evaluation of the performance of optical time transfer links connecting a facility of Deutsche Telekom in Bremen with the Physikalisch-Technische Bundesanstalt in Braunschweig. In the current configuration three links have been established, two via a hub in Hannover and one using an independent alternate route. They are equipped with electronically stabilized fiber optic time and frequency transfer systems and parallel operation is maintained since December 2016. A novel method of link calibration, composed of two steps (one performed in the laboratory and the second one in the field), to accurately determine the influence of fiber chromatic dispersion is discussed in detail, and a thorough analysis of the uncertainty budget is given. We show that the time transfer performance achieved is difficult to characterize based on measurements with time interval counters that are the standard equipment in timing laboratories and in the telecommunications sector. In our experiments, values of TDEV at the low ps-level at averaging times between 10 4 to 10 6 seconds have been achieved. The uncertainty of time transfer (including all kinds of delays) is of the order of 50 ps in a cascade of links. The results obtained show that such a kind of link is capable to deliver signals to a remote end with an instability being at least two orders of magnitude below the current requirements included in relevant Recommendations of the International Telecommunication Union-Telecommunication Sector (ITU-T). Moreover, the current implementation would allow primary Cs fountain clocks to be compared at the level of their performance, that is characterized by an uncertainty at the low 10-16 level and a frequency instability of the same order of magnitude at one day averaging.

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Section: Telecommunication Union-telecommunication Sector (Itu-t)mentioning

confidence: 99%

Calibrated optical time transfer of UTC(k) for supervision of telecom networks

et al. 2018

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“…In the last TSB of year 2018, the difference was about 2 ns. In Bauch et al, we discussed some potential causes for this mismatch which is, on the other hand, not relevant in the context of this paper.…”

Section: The Ptb Time Service Bulletinmentioning

confidence: 62%

“…Recently, the number of satellites increased in a way that the statistical component of the standard uncertainty could be decreased to only 0.5 ns (see Figure , right, and Bauch et al). The calibration of internal receiver delays for Galileo signals results in a systematic uncertainty of 4.2 ns (1σ) …”

Section: The Ptb Time Service Bulletinmentioning

confidence: 91%

“…The standard deviations amount to 0.87 ns for GPS and 0.48 ns for Galileo observations, respectively. These data are discussed in the context of the usage of time transfer using different GNSS signals in Bauch et al An analysis using the time deviation (lower plots in Figure ) points to periodic variations, likely due to the orbital period and small biases between the data from different satellites, which are differently pronounced for GPS and Galileo, respectively. The distribution of the data is not Gaussian like, precluding a simple “1/sqrt(N)” approach to compute the standard uncertainty.…”

Section: The Ptb Time Service Bulletinmentioning

confidence: 99%

“…The corresponding statistical uncertainty was initially estimated to be somewhat higher than those for GPS because the number of satellites of the Galileo constellation was too small which led to a higher statistical uncertainty contribution of typically 1.5 ns (1σ). Recently, the number of satellites increased in a way that the statistical component of the standard uncertainty could be decreased to only 0.5 ns (see Figure , right, and Bauch et al). The calibration of internal receiver delays for Galileo signals results in a systematic uncertainty of 4.2 ns (1σ) …”

Section: The Ptb Time Service Bulletinmentioning

confidence: 99%

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Disciplined oscillators for traceable frequency and time in metrology and financial sectors

et al. 2019

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Laboratory sources for standard frequency and time that receive external time signals to control their built-in oscillators are widely used wherever accurate and stable frequency and time, optionally with universal synchronization, are required. We propose a method to obtain traceability of such signals to Coordinated Universal Time (UTC) and particularly to UTC(PTB), its realization by the Physikalisch-Technische Bundesanstalt (PTB). The role of PTB's weekly published Time Service Bulletin is discussed in detail, and the metrological steps for establishing and maintaining traceability are described and uncertainty contributions are stated. Furthermore, we discuss how to possibly meet financial sector regulations according to European MiFID II. A procedure as a component for the assessment to provide accurate time through telecommunication networks using, eg, the Network Time Protocol (NTP) is presented. It checks outputs of an NTP server to validate that its time reference and provided timeof-day information is in accordance with specific requirements.

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Amelioration of the usage and Monitoring of GNSS Signals at PTB

Cited by 2 publications

References 0 publications

Calibrated optical time transfer of UTC(k) for supervision of telecom networks

Calibrated optical time transfer of UTC(k) for supervision of telecom networks

Disciplined oscillators for traceable frequency and time in metrology and financial sectors

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