Cesium-Beam Servo System Using Square-Wave Frequency Modulation

This paper describes a new modulation and servo system that is being tested in the NRC long-beam cesium-frequency standard. Square-wave frequency modulation is employed; it is introduced by switching between two separately generated frequencies. The synthesizer producing these frequencies and the problems caused by switching transients are described. Since in a laboratory standard systematic errors play a very important role these errors are discussed in the description of the servo system. The resulting systematic error as calculated from results of experiments on its components is less than 1 part in 10¹³.