TIME METROLOGY IN AZERBAIJAN. ESTIMATION OF THE QUANTITY

Time is one of the seven units in SI and its determination stands for some hundred years ago. The fundamental principle for measuring time is to take such kinds of events that happen periodically. The distance between the hyperfine energy levels of the atom never changes. The transition of electrons from the ground state to the excited state and vice versa (the hyperfine levels belong to the ground state) is the best event for the determination of time. Therefore, atomic clocks are the best devices for accurate time measurement. Atomic clocks are being used for different types of purposes in science, metrology, and technology. The atomic clock has ultra-high accuracy for keeping time. These devices have self-calibration mechanism which eliminates the periodic calibration. The internal comparator of the atomic clocks consistently compares the local atomic clock and PTB, NIST etc. time. The GPS satellites are boarded cesium clocks which have traceability of worldwide advanced laboratories and they provided all local GPS controlled atomic clocks with 1 pps (pulse per second) signals. The 1 pps signal indicates the starting of the second in every atomic clock. The the comparison of 1 pps signals are called phase deviation or time error (TE) which the basis of self-calibration. The Time and frequency laboratory is the primary state standard laboratory of the Azerbaijan Institute of Metrology and this laboratory is equipped by a rubidium based atomic clock and a frequency counter. This laboratory is the primary laboratory of the time metrology of Azerbaijan. The following paper will find out the determination of frequency offset, time delay, TE distribution. The distribution form of TE (its deviation and mean value) gives information about the state of atomic clocks. The value of mean TE is related with clock accuracy, the deviation is related with clock stability. Keywords: time, SI units, atomic clocks, metrology, measurement, calibration, TE