Selecting a Primary Frequency Standard for a Calibration Laboratory

Calibration laboratories can choose from a variety of frequency standards, including quartz oscillators, atomic oscillators, and oscillators disciplined to agree with reference signals from the Global Positioning System (GPS) satellites or other sources. The frequency calibration and measurement capability of a laboratory is largely determined by the type of primary frequency standard* that is chosen. This paper presents an overview of the various types of commercially available frequency standards. It discusses their specifications, and the pros and cons of owning and operating each type of standard. It also presents long-term performance data from a number of calibration laboratory frequency standards that are monitored by the National Institute of Standards and Technology (NIST) through its remote calibration services.