Frequency Transfer with New Broadband VLBI.–NMIJ-NICT Test Experiment–

High precision distant frequency transfer techniques are desired to compare the advanced atomic frequency standards (AFS), which are newly developed by metrological research institutes in the world. Fiber-link frequency transfer is the technique of current highest highest accuracy, although distance of comparison is limited by fiberlink. Two-way satellite time and frequency transfer (TWSTFT) is the technique used for high precision time and frequency transfer. Its drawbacks are dependency on geographical availability of satellite and running cost including transponder of satellite, radio signal transmission license. Space geodetic techniques such as Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) observations are passive method as the next choices for time and frequency transfer. VLBI observation determines the spatial coordinates of the station and clock difference simultaneously. The analysis is theoretically based on inertial reference frame using natural radio source fixed in celestial sphere. These features have advantages of VLBI in the aspect of long term stability of comparison than the other space techniques which uses artificial signal sources. We have developed a broadband VLBI system named GALA-V [1], which is designed for advanced delay precision with observing broad observation frequency range (3-14GHz).