Characterization of Delays for Spare SATRE Modems in TWSTFT Stations

Many timing laboratories are currently employing Two-way Satellite Time and Frequency Transfer technique to compare their respective time scales and contribute to the Coordinated Universal Time calculated monthly by the Bureau International des Poids et Mesures (BIPM). It is not unusual to implement multiple TWSTFT stations or install multiple modems to ensure redundancy. Some SATRE (SAtellite Time and Ranging Equipment) modems, which are widely used in this context, are manufactured with expansion slots for multiple signal receiving (RX) modules, increasing the capability for redundancy. In this case, it would be useful to characterize the different delays introduced between modems and between their RX modules, if applicable, in order to switch devices in the event of a module or system failure while maintaining service continuity and calibration results. This work presents the preliminary measurement results of the delays of various SATRE modems used: #079 and #416 at INRIM and #077 and #321 at LNESYRTE (OP).