Time and frequency measurement at NIST: the first 100 years

During this, the NIST Centennial Year, I look back on the first 100 years and summarize NIST work on time and frequency measurement, a topic of some prominence from the early years of the institution. Initial work at NIST (then NBS, the National Bureau of Standards) focused primarily on frequency standards needed to support the control of broadcast frequencies in the early days of radio. The Time and Frequency Division was not created until 1967, by which time a number of primary atomic frequency standards had already been developed, and it was clear that a broader program in this field was needed. This paper describes a variety of programs including the development of primary frequency standards, the international coordination of standards, statistical techniques for characterizing noise, dissemination methods, and methods for measuring optical frequency.