Establishment of a TWSTFT link between Asia and Europe connecting NICT and PTB

In this contribution we report on the installation of a two-way satellite time and frequency transfer link (TWSTFT) between NICT and PTB and discuss first observation results. Specific features of the architecture of the Earth stations are the use of the multi-channel time-transfer modems developed by NICT, which are also in operation in the Asia-Pacific TWSTFT network, and optical fiber connections for radio frequency transmission between indoor and outdoor equipment. Especially at PTB a distance of 1 km has to be bridged by that way. We have performed time transfer alternatively with two different reference sources, caesium standard based realizations of UTC and hydrogen masers (HM) at both sites, NICT and PTB. First results show Allan standard deviations at 10⁴ s of 1×10^-13 and 5×10^-14, respectively. This represents a significant improvement compared to the GPS based comparisons made hitherto. In a first approach towards an improvement of the TWSTFT stability we study the causes of diurnal variations appearing in the measurements.