Frequency standards for communications

The fundamentals of quartz and atomic frequency standards are reviewed. The subjects discussed include: crystal resonators and oscillators, atomic oscillators, oscillator types, and the characteristic and limitations of temperature-compensated crystal oscillators (TCXO), oven-controlled crystal oscillators (OCXO), rubidium frequency standards, cesium beam frequency standards and hydrogen masers. The oscillator instabilities discussed include: aging, noise, frequency vs. temperature, warmup, acceleration effects, magnetic field effects, atmospheric pressure effects, radiation effects, and interactions among the various effects. Guidelines are provided for oscillator comparison and selection. Discussions of time transfer techniques and specifications are also included, as are references and suggestions for further reading.