Time and Frequency Standard Laboratory

Head of the laboratory dr. Rimantas Miškinis,
phone +370 52620194

The mission of the Time and Frequency Standard Laboratory is the following:

  • to conduct scientific research in the field of time and frequency;
  • to reproduce the unit of time, the second (one second (s) is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom), and the unit of frequency, the hertz [Hz = 1/s] and to form the time scale UTC(LT) – the Lithuanian representation of the universal coordinated time (Universel temps coordonné, UTC);
  • to maintain the traceability of the magnitudes reproduced to the International system of units SI and to disseminate them to Lithuanian state and scientific establishments, legal and personal bodies by means of calibrating their measurement equipment and broadcasting the Lithuanian time scale via internet, etc.;
  • to take part in the formation of the international atomic time scale (Temps atomique international, TAI) and the universal coordinated time UTC. 
Operating principles of the standard and traceability. TFSL realizes the units of time and frequency as well as the time scale by means of its two cesium atomic clocks – Hewlett Packard 5071A and Agilent 5071A, which reproduce the second upon its definition. As well as other precise time laboratories of the world, TFSL is measuring and registering the time difference between its time scale and the time signals received from the GPS satellites. This is being done automatically by the time transfer systems TTS-2 and TTS-5. The comparison data obtained are transmitted to the Time Department of the International Bureau of Weights and Measures (Bureau International des Poids et Mesures, BIPM), which processes the data received from precise timing laboratories all over the world and forms the time scales TAI and UTC. UTC differs from TAI by some integer number of the so called leap seconds, which are from time to time added to UTC in order to keep its deviation from the astronomic time determined by the Earth’s rotation less than one second. In this way, BIPM forms a report called the Circular T, which reveals the evolution of differences between UTC (and TAI) and the time realized by every timing laboratory of the world. Therefore, all those laboratories are participating in a continuous international comparison.