Radio time signals are broadcast worldwide radio stations, two of these stations are WWV (Ft. Collins, Colorado), and WWVH (Maui, Hawaii). The signals are used for checking the accuracy of chronometers and other shipboard timepieces, they can be used as a means of setting the comparing watch or stopwatch prior to recording celestial observations. The time signals transmitted by station WWV (Bureau of Standards) This time is called Coordinated Universal Time differs from GMT by about 2 milliseconds per day.
Most stations transmit time signals for the five minutes immediately preceding certain hours of GMT, WWV and WWVH give the correct time by voice announcement every 5 minutes 24 hours a day. When tones alone are used, they are begun 5 minutes before the hour. The time signal is used to determine the error of your chronometer. The frequency for these stations are,2.5mHz, 5mHz, 10mHz, 15mHz. The frequency for best reception will depend on the time of day, and on atmospheric conditions. As rule, the 15 mHz band is good during the daylight hours, the 5 mHz band is usually better at night.
Each second is marked by an audible "tick" but the 29th and 59th seconds are not marked by a tick. Once each minute time is announced by voice in the last 15 seconds of the minute. The two stations are distinguished by a female voice from WWVH between 15 and 7 1/2 seconds before the minute, and a male voice from WWV between 7 1/2 and 0 seconds before the minute. The time is stated as Coordinated Universal Time, this can be used as GMT.
