Commissioning and validation of a GPS common-view time transfer service at NPL

Davis, John; Stevens, M. J.; Whibberley, Peter; Stacey, P. W.; Hlavac, R

doi:10.1109/freq.2003.1275231

Cited by 5 publications

(5 citation statements)

References 1 publication

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“…The reference delay represents the delay from the local UTC time scale to the end of the cable that connects to the SIM system. The time stability, σ x (τ) [13], of the common-clock calibrations is typically near 0.2 ns at τ = 1 d, agreeing well with other published results using similar receivers [6,14]. Fig.…”

Section: B Gps Data Collectionsupporting

confidence: 79%

“…The SIM measurement system uses an 8-channel GPS timing receiver identical to those included in other commonview systems used for international comparisons [6,10], and thus the performance of the SIM system is similar to those models. Although the GPS receiver is not ovenized, the temperature stability inside the rack-mount enclosure is reasonably good.…”

Section: A Gps Receiver and Antennamentioning

confidence: 99%

“…Since then, it has become a primary comparison technique for the derivation of UTC [4]. Common-view GPS is also used by NMIs to support remote calibration services that link to other metrology laboratories [5,6,7] or to industrial time users [8].…”

Section: Description Of Measurement Systemmentioning

confidence: 99%

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The inter-American metrology system (SIM) common-view GPS comparison network

Lombardi

Novick

López³

et al.

Proceedings of the 2005 IEEE International Frequency Control Symposium and Exposition, 2005.

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-The Inter-American Metrology System (SIM) consists of national metrology institutes in 34 member nations located throughout North, Central, and South America, and the Caribbean region. Currently, at least ten SIM laboratories pursue time and frequency metrology, and are responsible for maintaining the national time and frequency standards for their respective countries. To benefit these laboratories and advance metrology in the SIM region, we have developed a measurement network to continuously intercompare these standards and to make the data readily accessible to all SIM members. This network utilizes the multi-channel common-view GPS technique and the near real-time exchange of data via the Internet. This paper discusses the challenges of implementing the SIM comparison network, and provides a technical description of the measurement system supplied to participating laboratories. It describes the method used to calibrate the SIM measurement systems, and describes how the measurement results are processed and reported to the laboratories.

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Section: B Gps Data Collectionsupporting

confidence: 79%

Section: A Gps Receiver and Antennamentioning

confidence: 99%

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The inter-American metrology system (SIM) common-view GPS comparison network

Lombardi

Novick

López³

et al.

Proceedings of the 2005 IEEE International Frequency Control Symposium and Exposition, 2005.

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“…The time deviation σ x (τ) at an averaging period of 1 day is about 1.73 ns. Table 2 summarizes the performance of GPS common-view calibration systems developed by primary timing laboratories such as National Institute of Standards and Technology (NIST), National Physical Laboratory (NPL), National Institute of Information and Communications Technology (NICT) and TL [Davis et al, 2003;Gotoh, 2005;Lombardi et al, 2005;Lombardi and Novick, 2006]. The time comparisons were made by these calibration systems with different baseline distance.…”

Section: 1002/2014rs005460mentioning

confidence: 99%

Time and frequency transfer system using GNSS receiver

2014

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Global Positioning System (GPS) time and frequency transfer is one of the most useful ways for the comparison of remote clocks, and the comparison results are very important for the calculation of International Atomic Time and UTC (Coordinated Universal Time). For the timing laboratories, it is necessary to calibrate and periodically evaluate their time transfer system to ensure the accuracy and long-term stability of their time and frequency comparison results. Once the calibration is achieved, it can be used as a standard for traceable time and frequency measurements. In this paper, we demonstrate Global Navigation Satellite System receiver calibration campaign between the National Time and Frequency Standard Laboratory of Telecommunication Laboratories in Taiwan and the Measurement Standards Laboratory in New Zealand. Two calibration strategies, receiver calibration and the link calibration, are adopted in this work. The receiver calibration is used for evaluating the performance of the proposed system in domestic traceability network in Taiwan. The link calibration is used for minimizing the total uncertainty budget in calculating UTC. Experimental results indicate that the expanded time and frequency uncertainty of the proposed system (with a coverage factor of k = 2) are less than 25 ns and 1.1 × 10 À13 , respectively, after 1 day of averaging. The accuracy of GPS time link is reported to be better than 2 ns in long-baseline link (10,000 km) in Asia-Pacific Zone.

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“…Although the great majority of these products were designed for the positioning and navigation markets, a few products were optimized for timing applications. As a result, at least several national metrology institutes (NMIs) designed CGGTTS compatible receivers using eight-channel OEM boards, including the Borowiec Astrogeodymical Observatory (AOS) in Poland [9], the National Physical Laboratory (NPL) in the United Kingdom [10], and the National Institute of Metrology (NIM) in China [11]. Both the AOS and NPL receiver designs were once sold commercially, and are still used by a number of NMIs to contribute to UTC.…”

Section: Introductionmentioning

confidence: 99%

A Low-Cost Time Transfer Receiver for Contributions to Coordinated Universal Time

Lombardi

Novick

Zhang

2014

J. RES. NATL. INST. STAN.

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This paper describes a low-cost time transfer receiver that allows timing laboratories, including national metrology institutes and other designated institutions, to contribute data to the computation of Coordinated Universal Time (UTC). The time transfer receiver compares a laboratory’s local realization of UTC, to signals broadcast by Global Positioning System (GPS) satellites. It stores the measurement results in a format compatible with international standards, and sends data via the Internet to the Bureau International des Poids et Mesures (BIPM) for inclusion in the UTC computation. In addition to being inexpensive, the receiver was designed to be easy to use, allowing recently established timing laboratories to begin contributing to UTC with a minimal investment in training.

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Commissioning and validation of a GPS common-view time transfer service at NPL

Cited by 5 publications

References 1 publication

The inter-American metrology system (SIM) common-view GPS comparison network

The inter-American metrology system (SIM) common-view GPS comparison network

Time and frequency transfer system using GNSS receiver

A Low-Cost Time Transfer Receiver for Contributions to Coordinated Universal Time

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