A New Microwave Satellite Simulator for the determination of delays in a TWSTFT Station

The French national metrology institute for time and frequency LNE-SYRTE has developed a new microwave satellite simulator to be used as a calibration device for the determination and monitoring of the delay difference in its Ku-band two-way satellite time and frequency transfer (TWSTFT) earth station. Such a device is more and more recommended by the CCTF working group on TWSTFT in order to better evaluate the time transfer uncertainty component related to the variation of the earth station delay difference between two consecutive calibration campaigns. Besides few simulators commercially available based on the VSL design [1], we have realized a new calibration device with at least two different concepts from those currently in use: a faster delay calibration process and a characterization of its internal delays using a microwave vector network analyzer (MVNA). The key component of this simulator is the use of a double-balanced microwave mixer and its characterization in terms of absolute delay requires a specific measurement system such as an MVNA allowing a vector mixer calibration technique with the use of a characterized mixer/filter as a through standard. The measurements done with the MVNA are described in this paper. They are completed by those giving with the SATRE modem during calibration sessions, involving the earth station -which is driven by a hydrogen maser- and the satellite simulator [2].