The WWV time signal transmitter is located in the western United States at Fort Collins, Colorado. It operates on 2.5, 5, 10, 15, and 20 Mhz 24/7. Due to
the nature of radio propagation which changes from night to day the lower (2.5, 5, and 10 Mhz) frequencies are best at night and the higher (15 and 20 Mhz)
frequencies are best during the day. Which particular frequency is optimal will vary according to the time of day as well as season of the year and even
the state of solar activity. Embedded in the vocal time annoucement and second hand tick are timing signals which can be decoded by specialized equipment
and even a pc with specal software that has the audio from a shortwave recevier connected via the line-in jack. The signals sent are synchronized to an
atomic clock and are considered the most stable and accurate timing signals widely available on Earth.