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Share sensitive information only on official, secure websites. https://www.nist.gov/time-distribution/radio-station-wwv National Institute of Standards and Technology National Institute of Standards and Technology Search NIST [ ] Search Menu Close * Topics + All Topics + Advanced communications + Artificial intelligence + Bioscience + Buildings and construction + Chemistry + Climate + Cybersecurity + Electronics + Energy + Environment + Fire + Forensic science + Health + Information technology + Infrastructure + Manufacturing + Materials + Mathematics and statistics + Metrology + Nanotechnology + Neutron research + Performance excellence + Physics + Public safety + Resilience + Standards + Transportation * Publications * Labs & Major Programs + Laboratories o Communications Technology Laboratory o Engineering Laboratory o Information Technology Laboratory o Material Measurement Laboratory o Physical Measurement Laboratory + User Facilities o NIST Center for Neutron Research o CNST NanoFab + Research Test Beds + Research Projects + Tools & Instruments + Major Programs o Baldrige Performance Excellence Program o Manufacturing Extension Partnership (MEP) o Office of Advanced Manufacturing o Special Programs Office o Technology Partnerships Office * Services & Resources + Standards and Measurements o Calibration Services o Laboratory Accreditation (NVLAP) o Quality System o Standard Reference Materials (SRMs) o Standards.gov o Time Services o Office of Weights and Measures + Software + Data o Chemistry WebBook o National Vulnerability Database o Physical Reference Data o Standard Reference Data (SRD) + Storefront + License & Patents + Computer Security Resource Center (CSRC) + NIST Research Library * News & Events + News + Events + Video Gallery + Image Gallery + Feature Stories + Blogs + Media Contacts + SI Redefinition * About NIST + Learn About NIST + Contact Us + Visit + Careers + Our Organization o Mission, Vision & Values o Organization Structure o Office of the Director o Locations o People o Budget & Planning + Industry Impacts + Awards + Work with NIST + History o NIST Digital Archives o NIST Museum o NIST and the Nobel + Resources for Kids + Policies & Notices Physical Measurement Laboratory / Time and Frequency Division Time Realization and Distribution * Radio Station WWV Expand or Collapse + History of Radio Station WWV + Manufacturers of Time and Frequency Receivers + NIST Radio Broadcasts Frequently Asked Questions (FAQ) + Telephone Time-of-Day Service Expand or Collapse o Telephone Time-of-Day Service (2019) o Telephone Time-of-Day Service (2020) + WWV Photos + WWV and WWVH Broadcast Outages + WWV and WWVH Digital Time Code and Broadcast Format + WWV/WWVH Station Library Radio Station WWV Share Facebook Linkedin Twitter Email WWV building NIST radio station WWV broadcasts time and frequency information 24 hours per day, 7 days per week to millions of listeners worldwide. WWV is located near Fort Collins, Colorado, about 100 kilometers north of Denver. The broadcast information includes time announcements, standard time intervals, standard frequencies, UT1 time corrections, a BCD time code, and geophysical alerts. Broadcast Frequencies WWV operates in the high frequency (HF) portion of the radio spectrum. The station radiates 10 000 W on 5 MHz, 10 MHz, and 15 MHz; and 2500 W on 2.5 MHz and 20 MHz. Each frequency is broadcast from a separate transmitter. Although each frequency carries the same information, multiple frequencies are used because the quality of HF reception depends on many factors such as location, time of year, time of day, the frequency being used, and atmospheric and ionospheric propagation conditions. The variety of frequencies makes it likely that at least one frequency will be usable at all times. Antennas The WWV antennas are half-wave vertical antennas that radiate omnidirectional patterns. There are antennas at the station site for each frequency. Each antenna is connected to a single transmitter using a rigid coaxial line, and the site is designed so that no two coaxial lines cross. Each antenna is mounted on a tower that is approximately one half-wavelength tall. The tallest tower, for 2.5 MHz, is about 60 m tall. The shortest tower, for 20 MHz, is about 7.5 m tall. The top half of each antenna is a quarter-wavelength radiating element. The bottom half of each antenna consists of nine quarter-wavelength wires that connect to the center of the tower and slope downwards to the ground at a 45 degree angle. This sloping skirt functions as the lower half of the radiating system and also guys the antenna. WWV Antenna Coordinates Frequency (MHz) Latitude Longitude 2.5 40deg 40' 55.2" N 105deg 02' 31.3" W 5 40deg 40' 42.1" N 105deg 02' 24.9" W 10 40deg 40' 47.8" N 105deg 02' 25.1" W 15 40deg 40' 45.0" N 105deg 02' 24.5" W 20 40deg 40' 53.1" N 105deg 02' 28.5" W Modulation The signals broadcast by WWV use double sideband amplitude modulation. The modulation level is 50 percent for the steady tones, 50 percent for the BCD time code, 100 percent for the second pulses and the minute and hour markers, and 75 percent for the voice announcements. Experimental 25 MHz WWV Broadcast WWV has resumed broadcasting on 25 MHz on an experimental basis. The broadcast consists of the normal WWV signal heard on all other WWV frequencies, at the same level of accuracy. Current 25 MHz Broadcast Specifications Schedule: typically continuous. As an experimental broadcast, the 25 MHz signal may be interrupted or suspended without notice. Radiated Power: 2.5 kW Antenna: half-wave vertical dipole. Listener comments and reception reports may be emailed to: wwv [at] nist.gov (subject: , body: ) , or sent via postal mail to: National Institute of Standards and Technology Radio Station WWV 2000 E. County Rd. 58 Fort Collins, CO 80524 Time and frequency Contacts * NIST Radio nist.radio@boulder.nist.gov Created September 24, 2009, Updated January 30, 2020 * History of Radio Station WWV > National Institute of Standards and Technology logo HEADQUARTERS 100 Bureau Drive Gaithersburg, MD 20899 301-975-2000 Webmaster | Contact Us | Our Other Offices Twitter Facebook LinkedIn Instagram YouTube RSS Feed Mailing List How are we doing? Feedback * Site Privacy * Accessibility * Privacy Program * Copyrights * Vulnerability Disclosure * No Fear Act Policy * FOIA * Environmental Policy * Scientific Integrity * Information Quality Standards * Commerce.gov * Science.gov * USA.gov * Vote.gov