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The 2015 TWSTFT calibration for UTC and related time links

Published

Author(s)

Zhiheng Jiang, Dirk Piester, Christian Schlunegger, Erik Dierks, Javier Galindo, Demetrios Matsakis, Victor S. Zhang

Abstract

Two-Way Satellite Time and Frequency Transfer (TWSTFT or TW) is one of the primary time transfer techniques for UTC generation. Although it has expensive financial requirements it provides highly accurate calibration, and provides both robustness and complementarity to GNSS observations. For the generation of UTC, only the links involving the pivot laboratory (the PTB at present) need to be calibrated. They are a small part of the total number of links observed by the TW network. Some laboratories make use of TW time comparisons for applications other than UTC computation, and in such cases Triangle Closure Calibration (TCC) gives the opportunity to calibrate these links without direct, dedicated calibration measurements. The principle of TCC is based upon requiring the closure sum of the three co-joined links to be zero. If two of them are calibrated, we apply the necessary calibration correction to the third link to zero the closure sum. The systematic uncertainty (uB) of the third link is the RSS (square root of the summed squares) of the systematic uncertainties of the calibrated links' values and the closure sum standard deviations. In this paper, a review of the TCC method is presented, followed by the results of the BIPM 2015 calibration computation. Finally, we discuss the comparison between the TW and the GPS time link, which have been calibrated independently in recent years.
Proceedings Title
The European Frequency and Time Forum (EFTF)
Conference Dates
April 4-7, 2016
Conference Location
York, UK
Conference Title
30th European Frequency and Time Forum

Keywords

Calibration, CALR, ESDVAR, TCC, TWSTFT or TW, TW Network, Uncertainty

Citation

Jiang, Z. , Piester, D. , Schlunegger, C. , Dierks, E. , Galindo, J. , Matsakis, D. and Zhang, V. (2016), The 2015 TWSTFT calibration for UTC and related time links, The European Frequency and Time Forum (EFTF), York, UK (Accessed February 24, 2024)
Created April 3, 2016, Updated October 12, 2021