Optimizing the Configuration of Time-Transfer Links Used to Generate TAI

摘要

This is the report of Study Group II of the Working Group on TAI, which was formed to study two of the three proposals in the BIPM Technical Memo 132, circulated in December, 2004. It is recommended that TAI be generated through combinations of Two Way Satellite Time and Frequency Transfer (TWSTFT) links and GPS links. It is assumed that Study Group I will not oppose acceptance of the first proposal, which is that GPS links will be converted from Common View (CV) to All in View (AV). In that case, we find benefits to the use of AV in order to optimize the link configurations, and also recommend in principle the acceptance of the second of the proposals, which was to adapt a single pivot. We specify the optimal requirements for the site selection and site maintenance, but we note that the lack of low-noise connectivity between the Asian and American-European TWSTFT links may require two pivot sites instead of one. We recommend against the third proposal, which is the introduction of a virtual pivot. We do not recommend averaging time-transfer techniques over TAI-generating links until the possibilities are further studied, and recommend that the BIPM staff give priority to developing carrier phase GNSS links over developing the averaging of redundant links.