An introduction to frequency standards

Quartz oscillators and rubidium, cesium, and hydrogen atomic frequency standards are described in terms of the physics of operation. Sources of frequency instability and inaccuracy are given. The author´s intention is to provide a basis for characterization of the more practical aspects of commercially available frequency standards, and to present a comparison of such standards which may be useful in selecting devices for various applications. Emphasis is laid on stability performance of precision frequency standards, but some discussion is also given of other physical characteristics and cost considerations