Second - Meinberg Radio Clocks

Solutions for Time and Frequency Synchronization

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Second

In the SI-system of units the second is defined by an atomic time normal, due to the fact that compared to astronomic time standards (e.g. "sun or ephemeris second) a higher accuracy and long-term consistency can be assured. Due to definition, a second is based on the period of a Microwave which is in resonance with the transition of a caesium atom, multiplied by 9.192.631.770. A second can therefore be described as 9.192.631.770 times the duration of a period of a transition between two special levels of the ground state of the Nuclides of a 133 Caesium atom's radiation. This determination has been introduced to ensure the average duration of one day of sun, which has to conform to the position of the sun being at the same location after one full turn. Because of some irregularities due to the slowing down of the earth rotation leap seconds have been introduced.

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