Atomic Clocks and Timing Systems in Global Navigation Satellite Systems

Accurate and ultra-stable atomic clocks have been recognized as the critical equipment for the precision Global Navigation Satellite Systems (GNSSGlobal navigation satellite system (GNSS): A general term describing any satellite constellation that provides positioning, navigation, and timing (PNT) services on a global or regional basis. See also). Safran and T4Science (T4S) are space and ground clocks manufacturers of Rubidium Atomic Frequency Standard (RAFSThe Rubidium Atomic Frequency Standard is 10.00 MHz which is a space-qualified frequency standard by which all atomic clocks are measured by. The 10.00 MHz frequency is derived by the spectral absorption line of the Rb87 isotope.) and Active & Passive Hydrogen Maser (HM) for various navigation systems (European, Chinese and Indian) and other programs.