The United States Bureau of Standards radio station which broadcasts time and frequency standards. WWV (Ft. Collins, Colorado) and WWVH (Maui, Hawaii) broadcast continuously on 2.5, 5, 10, 15, 20, and 25 MHz (the last 2 only by WWV). WWV is off the air for 4 min commencing at 45 min 15 s after each hour and WWVH for 4 minutes commencing at 15 min 15 s after each hour. Each second is marked by a signal or tick. A voice announcement is given every minute, for example, ‘‘National Bureau of Standards, WWV, Fort Collins, Colorado. At the tone, 17 hr, 16 min, Coordinated Universal time.’’ WWVB broadcasts a binary-coded-decimal version of WWV.