Broadcasts are found in the VHF public service band at these seven frequencies (MHz): NWR requires a special radio receiver or scanner capable of picking up the signal. NWR includes more than 1000 transmitters, covering all 50 states, adjacent coastal waters, Puerto Rico, the U.S. Known as the "Voice of NOAA's National Weather Service," NWR is provided as a public service by the National Oceanic and Atmospheric Administration (NOAA), part of the Department of Commerce. In conjunction with Federal, State, and Local Emergency Managers and other public officials, NWR also broadcasts warning and post-event information for all types of hazards – including natural (such as earthquakes or avalanches), environmental (such as chemical releases or oil spills), and public safety (such as AMBER alerts or 911 Telephone outages). Working with the Federal Communication Commission's (FCC) Emergency Alert System, NWR is an "All Hazards" radio network, making it your single source for comprehensive weather and emergency information. NWR broadcasts official Weather Service warnings, watches, forecasts and other hazard information 24 hours a day, 7 days a week. Listener comments and reception reports may be emailed to: wwv nist.NOAA Weather Radio All Hazards (NWR) is a nationwide network of radio stations broadcasting continuous weather information directly from the nearest National Weather Service office.
As an experimental broadcast, the 25 MHz signal may be interrupted or suspended without notice.Īntenna: half-wave vertical dipole. The broadcast consists of the normal WWV signal heard on all other WWV frequencies, at the same level of accuracy. WWV has resumed broadcasting on 25 MHz on an experimental basis. 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. The signals broadcast by WWV use double sideband amplitude modulation. This sloping skirt functions as the lower half of the radiating system and also guys the antenna. 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. The top half of each antenna is a quarter-wavelength radiating element. The shortest tower, for 20 MHz, is about 7.5 m tall. The tallest tower, for 2.5 MHz, is about 60 m tall. Each antenna is mounted on a tower that is approximately one half-wavelength tall. 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. There are antennas at the station site for each frequency.
The WWV antennas are half-wave vertical antennas that radiate omnidirectional patterns. The variety of frequencies makes it likely that at least one frequency will be usable at all times. 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. Each frequency is broadcast from a separate transmitter. The station radiates 10 000 W on 5 MHz, 10 MHz, and 15 MHz and 2500 W on 2.5 MHz and 20 MHz. WWV operates in the high frequency (HF) portion of the radio spectrum. The broadcast information includes time announcements, standard time intervals, standard frequencies, UT1 time corrections, a BCD time code, and geophysical alerts. WWV is located near Fort Collins, Colorado, about 100 kilometers north of Denver. NIST radio station WWV broadcasts time and frequency information 24 hours per day, 7 days per week to millions of listeners worldwide.
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