Synthesis chains based on ultra-stable cryogenic sapphire oscillator at NICT

A synthesis chain based on a cryogenic sapphire oscillator (CSO) has been developed at NICT. The 11.2005 GHz output of the CSO is down-converted to 1-GHz for laboratory distribution. The short-term frequency stability of the down-converter itself is better than 1 times 10
^-15
at an averaging time of 1 second. The long-term drift of the CSO is suppressed by referencing it to a hydrogen maser linked to Japan Standard Time. For microwave interrogation to the cesium atom, a 9.192-GHz up-converter was developed.