The Time Scale Laboratory realizes UTC(IT), the Italian reference time scale used as the national legal time. UTC(IT) is generated from a robust ensemble of commercial frequency standards (hydrogen masers, cesium beam clocks, and cold rubidium atomic clocks) that provide short-term stability and long-term continuity. The ensemble is maintained with redundancy and continuous performance checks, so that the time scale can operate without interruption and with controlled behavior during maintenance or component replacement.
The ensemble output is supported and periodically calibrated by INRiM’s state-of-the-art standards, including the cesium fountain primary standard (for the current realization of the second) and the ytterbium optical lattice clock (for ultra-low uncertainty in the optical domain). Their measurements are used to validate the ensemble, estimate frequency offsets and drifts, and reduce systematic biases, thereby strengthening the accuracy and traceability of UTC(IT).
The current plan foresees an improvement of the robustness of UTC(IT) generation architecture, and the realization of a time laboratory at the INRiM Matera site. Matera will be connected to Torino via GNSS and an optical-fiber link, providing geographical diversification and an additional operational node for timing activities.
A key development is the progressive integration of optical clocks into time-scale generation, with the objective of improving long-term performance of the national time scale.
UTC(IT) is continuously compared with the time scales generated by other National Metrology Institutes using satellite-based time and frequency transfer. These comparisons support INRiM’s contribution to the Bureau International des Poids et Mesures (BIPM), for the generation of the international time scales TAI and UTC. The same comparison infrastructure also supports timing studies linked to GNSS and satellite navigation.
UTC(IT) is the reference for INRiM dissemination services, including time and frequency distribution through different technologies, supporting both scientific and industrial users. The laboratory provides the measurement and data-analysis chain needed to quantify the offset between dissemination services and UTC(IT), ensuring traceability to the national reference. This combination of continuous operation, metrological traceability and international comparison makes UTC(IT) a reliable reference for applications ranging from telecom and power grids to time-stamping in high-precision experiments.