Carrier-phase two-way satellite frequency transfer between LNE-SYRTE and PTB

We performed a carrier-phase two-way satellite frequency transfer (TWCP) experiment between LNE-SYRTE and PTB for several days in September 2015. Different hardware configurations were analyzed at the LNE-SYRTE earth station and a suitable configuration was identified by placing up- and down-converters indoors. Additionally atomic fountain frequency standards were operated simultaneously at both institutes. This offered a comparison of two reference clocks at LNE-SYRTE and PTB independently by means of TWCP and via the fountain clocks. Even with a very limited and not continuous measurement time of about 8 hours for TWCP measurements, a frequency transfer uncertainty below 2×10−15 was achieved and the results by the fountain clocks and TWCP agreed well within this uncertainty.