Real-time formation of a time scale using GPS carrier-phase time transfer network

Lee, Seung-Woo

doi:10.1088/0026-1394/46/6/012

Cited by 13 publications

(7 citation statements)

References 20 publications

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“…Variations in temperature and hardware may also have some effect. Similar characteristics are exhibited in figures presented by Defraigne and Petit [] and Lee []. Further work is required to conclusively determine why the MIDAS curve does not exhibit this bump.…”

Section: Resultssupporting

confidence: 76%

Ionospheric corrections for GPS time transfer

et al. 2014

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A real-time ionospheric mapping system is tested to investigate its ability to compensate for the ionospheric delay in single-frequency Global Positioning System (GPS) time transfer over Europe. This technique is compared with two other single-frequency systems: one that does not incorporate any ionospheric correction and one that uses the broadcast Klobuchar model. A dual-frequency technique is also shown as a benchmark. A period in March 2003, during a solar maximum, has been used to display results when the ionospheric delays are large and variable. Data from two European GPS monitoring centers were used to test the time-transfer methods. For averaging times between several minutes and a few hours, the instabilities in the time transfers were dominated by ionospheric effects. The instabilities at longer averaging times were found to be due to clock noise and hardware instabilities. Improvements in time-transfer instabilities are shown by using the ionospheric tomography system.

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Section: Resultssupporting

confidence: 76%

Ionospheric corrections for GPS time transfer

et al. 2014

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“…A long period of data is needed to smooth the noise induced by the transfer process. Thus, time scales based on satellite links are mostly computed in deferred time or have calculation intervals of no less than one day [4,[8][9][10].…”

Section: Real-time Free-running Time Scale With Remote Clocks On Fibe...mentioning

confidence: 99%

Real-time free-running time scale with remote clocks on fiber-based frequency network

Guo

Wang

et al. 2019

Metrologia

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In this paper, we propose a real-time free-running time scale based on four remote hydrogen masers. The clocks in the ensemble were scattered around Beijing, connected by urban fiber links using a novel frequency synchronization system. The remote clock ensemble prevents the time scale from potential problems caused by correlation among co-located clocks. Insofar as it is real-time, it fulfills the requirements for applications such as navigation, telecommunications and so on. The free-running time scale is updated every 1200 s, and a disturbance-resistant algorithm makes it robust to fiber link disturbances and clock malfunctions. The results of a continuous experiment over 224 days are reported. The stability of the time scale outperformed any clock in the ensemble for averaging times of more than approximately 10 4 s.

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“…Currently, the main method in use is via satellite links, for example, the technique of Global Positioning System (GPS) and two-way satellite time and frequency transfer (TWSTFT) [27]. These methods could achieve sub-nanosecond-level precision in real-time comparison and frequency stability at the 10-15/day level in terms of Allan deviation [28]. However, this is not sufficient to transfer signals of hydrogen masers at short averaging times [29].…”

Section: Coefficient Of Clock Correlationmentioning

confidence: 99%

The correlation of co-located hydrogen masers

Guo,

Wang,

et al. 2017

Preprint

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The correlation of co-located hydrogen masers (H-masers) is difficult to measure because their common-mode noise induced by the environment will be cancelled out during the comparison measurement. With the development of fibre-based high-precision time and frequency transfer technique, the correlation of co-located hydrogen masers can be directly measured with the help of remote Hmasers. Recently, a fiber-based frequency synchronization network was constructed in the Beijing region by connecting 5 H-masers from 4 institutions. The correlation coefficient of atomic clocks is defined and the correlation between two co-located H-masers is measured using both experimental and simulative methods. The results show that the correlation is not prominent until the averaging time is larger than ∼ 10 3 s; then, the coefficient grows rapidly for averaging times ranging from ∼ 10 3 s to ∼ 10 5 s and decreases beyond ∼ 10 5 s up to 5 days.

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Real-time formation of a time scale using GPS carrier-phase time transfer network

Cited by 13 publications

References 20 publications

Ionospheric corrections for GPS time transfer

Ionospheric corrections for GPS time transfer

Real-time free-running time scale with remote clocks on fiber-based frequency network

The correlation of co-located hydrogen masers

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