atomic frequency standard
Atomic frequency standards are high-precision time standards characterized by high long-term frequency stability and constancy, which are in the order of `10^ -11` to `10^-14`. They are time-accurate measurement standards which the Physikalisch-Technische Bundesanstalt(PTB) sends as time reference and uses in atomic clocks.
Atomic frequency standards are based on time- constant oscillations of free atoms of certain chemical elements. These oscillations occur during the electronic transition between two hyperfine energy levels of the electrons in the atoms of the corresponding chemical elements and are released as electromagnetic radiation.
The elements with the highest vibrational constancy are rubidium 87 (Rb) and cesium 133 (Cs). For rubidium, the released frequency is 6.834682613 GHz, and for cesium it is 9.192631770 GHz. The long-term constancy of rubidium standards is `10^-11` to `10^-13`, for cesium standards it is one power of ten higher, the values being affected by temperature influences, by the earth's magnetic field and electromagnetic interference fields.
Atomic frequency standards are used as time standards and frequency standards, for the generation of time signals, in GPS systems for satellite navigation, as highly accurate timers in rail, air and marine traffic as well as in telecommunications and mobile radio networks, in radio technology, communications technology, satellite technology, network technology and transmitter technology and in many other areas. They can be designed in compact package construction as Chip Scale Atomic Clock( CSAC) or as plug-in units for racks.