13 March 2015
LNE-SYRTE developed two TWSTFT ground stations equipped with SATRE modems to transmit and receive real-time signals from atomic clocks by microwave links through a geostationary communications satellite operated in the Ku-band. This high permormance technique allows to directly compare remote atomic, the geostationary satellite is used as relay for microwave signals.
The goal is twofold: to make a better contribution of French atomic clocks in the implementation of International Atomic Time (TAI) calculated by the BIPM and provide an effective way for comparing the frequency primary standards of our laboratory with those of European and international metrolgy institutes.
Since January 2005, the primary satellite link of the laboratory uses the TWSTFT method for connecting UTC(OP) to UTC, as calculated and published by the BIPM. The difference UTC-UTC(OP) is determined with a combined uncertainty of less than 2 ns.
One of our two stations is also equipped with a satellite simulator developed within the team to assess the differential delay variations of the main station that contributes to the connection to TAI / UTC.