WWV Radio Station: A Century of Precision Timekeeping

Since 1945, a steady pulse has radiated from near Fort Collins, Colorado, providing a vital service to the world: accurate time. WWV is a shortwave, or high frequency (HF), radio station that implements United States government frequency standards. Operated by the National Institute of Standards and Technology (NIST), it serves as a cornerstone for time synchronization across the globe.

Established in 1919 by the Bureau of Standards, WWV is one of the oldest continuously operating radio stations in the United States. In 2019, NIST celebrated the station's centennial, marking a hundred years of scientific broadcasting.

Key Facts

• Operator: NIST (National Institute of Standards and Technology).
• Location: Near Fort Collins, Colorado.
• Frequencies: 2.5, 5, 10, 15, 20, and 25 MHz.
• Time Standard: Coordinated Universal Time (UTC).
• History: Established in 1919; continuous time signals since 1945.

Technical Operations and Frequencies

WWV transmits on several shortwave frequencies to ensure wide-reaching coverage. These transmissions provide the time of day in Coordinated Universal Time (UTC), along with other recorded announcements of general interest, such as the status of the Global Positioning System (GPS) satellite constellation.

To prevent confusion with its sister station, WWVH (located on Kauai, Hawaii), WWV uses a male voice for its announcements. WWVH, which also broadcasts in UTC, utilizes a female voice. While WWV operates in the shortwave spectrum, it shares its Colorado site with WWVB, a longwave (low frequency) station transmitting at 60 kHz.

Transmission Frequency Coordinates

The station utilizes specific antenna coordinates for its various frequency outputs to maintain signal integrity:

WWV Antenna Coordinates (WGS84)

Frequency (MHz)	Latitude	Longitude
2.5	40°40′55.0″N	105°2′33.6″W
5	40°40′41.9″N	105°2′27.2″W
10	40°40′47.7″N	105°2′27.4″W
15	40°40′44.8″N	105°2′26.9″W
20	40°40′52.8″N	105°2′30.9″W
25	40°40′50.8″N	105°2′32.6″W

The Anatomy of a Time Signal

WWV's signal is designed for both human listening and automated machine synchronization. The station transmits audio "ticks" once per second. These ticks are 5 ms long, consisting of five cycles of a 1,000 Hz sine wave. To ensure the tick is distinct, the station suppresses other signals for 40 ms around the second mark.

Minute and Hourly Markers

The station uses specific tones to mark the passage of time:

• Minute Marker: On the minute, the one-second tick is extended into a 0.8-second beep.
• Hourly Marker: On the hour, the minute pulse is transmitted at a higher pitch of 1,500 Hz.
• Musical Reference: During the second minute of every hour (except the first hour of the UTC day), a 440 Hz tone is broadcast. This is the musical note A440, often used by chart recorders to mark the passage of hours.

Digital Time Code

Beyond audible tones, WWV transmits a binary-coded decimal time code. This is modulated onto a 1 kHz audio tone as a 100 Hz subcarrier. This digital data allows receivers to automatically extract the exact year, day of the year, hour, minute, and even leap second status or Daylight Saving Time information.

Historical Evolution

The history of WWV is a journey through the evolution of radio technology. Originally established in Washington, D.C., the station moved to suburban Maryland in 1931 before settling near Fort Collins in 1966. This move significantly improved signal reception across the continental United States.

In its early years, the station's capabilities were more limited. In 1944, it began using the United States Naval Observatory clock as its source. By 1950, voice announcements were introduced, and by 1961, the digital "NASA time code" became a permanent fixture. The station has also transitioned through various time standards, moving from local time to Greenwich Mean Time (GMT), and finally to Coordinated Universal Time (UTC) in 1974.

Frequently Asked Questions

How can I access the WWV time signal by phone?

You can access the signal by calling +1 (303) 499-7111. Please note that calls are limited to 2 minutes and there is an average delay of 30 milliseconds due to network propagation.

What is the difference between WWV and WWVH?

Both stations provide UTC time, but they are located in different places (Colorado and Hawaii, respectively) and use different voices (male for WWV and female for WWVH) to help listeners distinguish between them.

What are the audio tones used by the station?

WWV uses alternating tones to help identify the station: 500 Hz during even-numbered minutes and 600 Hz during odd-numbered minutes. A special 440 Hz tone is also used once per hour.

Does WWV provide weather information?

While WWV previously broadcast marine storm warnings from the National Weather Service, all weather content was discontinued on February 7, 2019.

What does the call sign "WWV" mean?

The letters WWV are simply a call sign used for identification and do not stand for any specific words or acronyms.