NIST time and frequency radio stations: WWV, WWVH, and WWVB

The National Institute of Standards and Technology (NIST) provides standard time and frequency information through three radio broadcast stations that are routinely used by millions of customers. The stations, WWV and WWVB, located in Fort Collins, Colorado, and WWVH, located on the island of Kauai in Hawaii, are the only radio stations located in the United States whose sole purposes are to distribute standard time and frequency information. This document provides a comprehensive look at the NIST time and frequency radio stations. It provides a physical and technical description of each station, and describes how the stations are operated by NIST. It also examines how the stations are used by their customers, and estimates the measurement uncertainties of the radio signals, both as transmitted by NIST and as received by customers.