Information Transmitted by WWV and WWVH
WWV & WWVH WWVB Computer Telephone
- Time Announcements
- Standard Time Intervals
- Standard Frequencies
- UT1 Time Corrections
- BCD Time Code
- Geophysical Alerts
- Marine Storm Warnings
- Global Positioning System (GPS) Status Reports
Voice announcements are made from WWV once every minute. The WWVH announcement occurs first, at about 15 s before the minute. The WWV announcement follows at about 7.5 s before the minute. The announced time is "Coordinated Universal Time" (UTC). UTC was established by international agreement in 1972, and is governed by the International Bureau of Weights and Measures (BIPM) in Paris, France. Coordination with the international UTC time scale keeps NIST time signals in close agreement with signals from other time and frequency stations throughout the world.
UTC differs from your local time by a specific number of hours. The number of hours depends on the number of time zones between your location and the location of the zero meridian (which passes through Greenwich, England). When local time changes from Daylight Saving to Standard Time, or vice versa, UTC does not change. However, the difference between UTC and local time does change-by 1 hour.
UTC is a 24-hour clock system. The hours are numbered beginning with 00 hours at midnight through 12 hours at noon to 23 hours and 59 minutes just before the next midnight.
The most frequent sounds heard on WWV and WWVH are the seconds pulses. These pulses are heard every second except on the 29th and 59th seconds of each minute. The first pulse of each hour is an 800 ms pulse of 1500 Hz. The first pulse of each minute is an 800 ms pulse of 1000 Hz at WWV and 1200 Hz at WWVH. The remaining seconds pulses are short audio bursts (5 ms pulses of 1000 Hz at WWV and 1200 Hz at WWVH) that sound like the ticking of a clock.
Each seconds pulse is preceded by 10 ms of silence and followed by 25 ms of silence. The second marker for the broadcast is at the end of the 10 ms period and the start of the 5 ms period. The station's on-time marker is synchronized with the start of the 5 ms tone. The silence before and after the pulses makes it easier to identify the second pulses. As shown in the graphic below, the total zone around the second pulses lasts for 40 ms, consisting of 10 ms of silence, the 5 ms tone, and another 25 ms of silence. Then, the standard frequency audio tones resume.
Format of WWV and WWVH seconds pulses.
Both WWV and WWVH broadcast standard frequency audio tones that alternate during most minutes of the hour. Most minutes feature a 500 or 600 Hz audio tone. However, a 440 Hz tone is broadcast once per hour, and some minutes do not include any audio tones at all.
The schedule for the audio tones is listed in the table, with the minutes labeled from 0 to 59.
|500 Hz||WWV||4, 6, 12, 16, 20, 22, 24, 26, 28, 32, 34, 36, 38, 40, 42, 52, 54, 56, 58|
|500 Hz||WWVH||3, 5, 7, 11, 13, 21, 23, 25, 27, 31, 33, 35, 37, 39, 41,|
43 to 45, 47 to 51, 53, 55, 57
|600 Hz||WWV||1, 3, 5, 7, 11, 13, 17, 19, 21, 23, 25, 27, 31, 33, 35, 37,|
39, 41, 53, 55, 57
|600 Hz||WWVH||2, 4, 6, 12, 20, 22, 24, 26, 28, 32, 34, 36, 38, 40, 42, 46,|
52, 54, 56, 58
|None||WWV||0, 8 to 10, 14 to 15, 18, 29 to 30, 43 to 51, 59|
|None||WWVH||0, 8 to 10, 14 to 19, 29 to 30|
The 440-Hz tone (the musical note A above middle C) is broadcast once each hour, during minute 2 on WWV, and minute 1 on WWVH. In addition to being a musical standard, the 440-Hz tone provides an hourly marker for chart recorders and other automated devices. The 440-Hz tone is omitted, however, during the first hour of each UTC day.
The UTC time scale broadcast by WWV and WWVH meets the needs of most users. UTC runs at an almost perfectly constant rate, since its rate is based on cesium atomic frequency standards. Surprisingly, some users need time that is related to the rotation of the Earth, which is less stable than UTC. Applications such as celestial navigation, satellite observations of the Earth, and some types of surveying require time referenced to the rotational position of the Earth. These users rely on the UT1 time scale. UT1 is derived by astronomers who monitor the speed of the Earth's rotation.
You can obtain UT1 from the time signals broadcast by WWV and WWVH. UT1 is available at two levels of accuracy. If you need UT1 with an uncertainty of 1 s, you can simply use UTC, since the two time scales are always kept within 0.9 s of each other. Occasional corrections of exactly 1 s are inserted into the UTC time scale to keep the two time scales in agreement. These corrections, called leap seconds, are coordinated under international agreement by the International Earth Rotation Service. Leap seconds can be either positive or negative, but so far, only positive leap seconds have been needed. A positive leap second is normally added every 1 or 2 years, usually on June 30 or December 31.
If you need UT1 with an uncertainty of 0.1 s, you can apply a correction to UTC. UT1 corrections are encoded into the broadcasts by using doubled ticks during the first 16 s of each minute. You can determine the amount of the correction (in units of 0.1 s) by counting the number of doubled ticks. The sign of the correction depends on whether the doubled ticks occur in the first 8 s of the minute or in the second 8 s. If the doubled ticks are in the first 8 s (1-8) the sign is positive. If the doubled ticks are in the second 8 s (9-16) the sign is negative. For example, if ticks 1, 2, and 3 are doubled, the correction is +0.3 s. This means that UT1 equals UTC plus 0.3 s. If UTC is 8:45:17, then UT1 is 8:45:17.3. If ticks 9, 10, 11, and 12 are doubled, the correction is -0.4 s. If UTC is 8:45:17, then UT1 is 8:45:16.6. If none of the ticks are doubled, then the current correction is 0.
WWV and WWVH continuously broadcast a binary coded decimal (BCD) time code on a 100-Hz subcarrier. The time code presents UTC information in serial fashion at a rate of 1 pulse per second. The information carried by the time code includes the current minute, hour, and day of year. The time code also contains the 100-Hz frequency from the subcarrier. The 100-Hz frequency may be used as a standard with the same accuracy as the audio frequencies.
Click here to view the time code format.
The National Oceanic and Atmospheric Administration (NOAA) uses WWV and WWVH to broadcast geophysical alert messages that provide information about solar terrestrial conditions. Geophysical alerts are broadcast from WWV at 18 minutes after the hour and from WWVH at 45 minutes after the hour. The messages are less than 45s in length and are updated every 3 hours (typically at 0000, 0300, 0600, 0900, 1200, 1500, 1800, and 2100 UTC). More frequent updates are made when necessary.
The geophysical alerts provide information about the current conditions for long distance HF radio communications. The alerts use a standardized format and terminology that requires some explanation. Before looking at a sample message, lets define some of the terminology:
Solar flux is a measurement of the intensity of solar radio emissions with a wavelength of 10.7 cm (a frequency of about 2800 MHz). The daily solar flux measurement is recorded at 2000 UTC by the Dominion Radio Astrophysical Observatory of the Canadian National Research Council located at Penticton, British Columbia, Canada. The value broadcast is in solar flux units that range from a theoretical minimum of about 50 to numbers larger than 300. During the early part of the 11-year sunspot cycle, the flux numbers are low; but they rise and fall as the cycle proceeds. The numbers will remain high for extended periods around sunspot maximum.
The A and K indices are a measurement of the behavior of the magnetic field in and around the earth. The K index uses a scale from 0 to 9 to measure the change in the horizontal component of the geomagnetic field. A new K index is determined and added to the broadcast every 3 hours based on magnetometer measurements made at the Table Mountain Observatory, north of Boulder, Colorado, or an alternate middle latitude observatory. The A index is a daily value on a scale from 0 to 400 to express the range of disturbance of the geomagnetic field. It is obtained by converting and averaging the eight, 3-hour K index values. An estimate of the A index is first announced at 2100 UTC, based on 7 measurements and 1 estimated value. At 0000 UTC, the announced A index consists entirely of known measurements, and the word "estimated" is dropped from the announcement.
Space Weather describes the conditions in space that affect earth and its technological systems. Space weather is a consequence of the behavior of the sun, the nature of earths magnetic field and atmosphere, and our location in the solar system.
Space Weather storms observed and expected are characterized using the NOAA Space Weather scales. The abbreviated table below shows the levels of activity that are included in the announcements and the associated terminology. The descriptor used to identify observed or expected conditions is the maximum level reached or predicted. The NOAA Space Weather Scales are further described at the Space Environment Centers web site.
NOAA Space Weather Scales
Solar Radiation Storms
Geomagnetic storm levels are determined by the estimated 3-hourly Planetary K-indices derived in real time from a network of western hemisphere ground-based magnetometers.
Geomagnetic Storm Levels
|Planetary K indices||Geomagnetic storm level|
K = 5
K = 6
K = 7
K = 8
Solar Radiation storms levels are determined by the proton flux measurements made by NOAAs primary Geostationary Operational Environmental Satellite (GOES).
Solar Radiation Storm Levels
|Flux level of > 10 MeV particles||Solar Radiation Storm level|
Radio Blackout levels are determined by the x-ray level measured by the primary GOES satellite.
|Peak x-ray level and flux||Radio Blackout level|
|M1 and (10-5)||R1|
|M5 and (5 x 10-5)||R2|
|X1 and (10-4)||R3|
|X10 and (10-3)||R4|
|X20 and (2 x 10-3)||R5|
Every geophysical alert consists of three parts as shown in the two tables below. The first table describes the information contained in the geophysical alert. The second table provides example text from an actual message.
Information in Geophysical Alert Voice Message
|Section||Information in Voice Message|
|1||The solar-terrestrial indices for the day: specifically the solar flux, the A index, and the K index.|
|2||Space Weather storms observed during the previous 24 hours. Includes all observed geomagnetic storms, solar radiation storms (proton events) and Radio blackouts (class M1 and greater flares).|
|3||Space Weather expected during the following 24 hours.|
Example Text from Actual Geophysical Alert Message
|Section||Example of Actual Geophysical Alert Message|
|1||Solar-terrestrial indices for 08 November follow.|
Solar flux 173 and Mid-Latitude A-index 14
The Mid-latitude K-index at 1500 UTC on 08 November was 3.
|2||Space Weather for the past 24 hours has been severe.|
Solar radiation storm(s) reaching the S4 level is in progress.
Radio blackouts(s) reaching the R2 level occurred.
Alternate section 2
No Space Weather storms have been observed during the past 24 hours.
Space Weather for the next 24 hours is expected to be severe.
Solar radiation storms reaching the S4 level are expected to continue. Radio blackouts reaching the R2 level are expected.
Alternate section 3
No Space Weather storms are expected during the next 24 hours.
The announcements include the descriptor of the largest space weather event observed (2) or expected (3) in the first line of each section. The remaining lines give the type of events and the level observed for each one. In the example above, no geomagnetic storm information is included because none was observed or is expected during the period. In the case where none of the three types of events are observed or expected, the announcement would contain section 1, plus alternate section 2 and alternate section 3.
To hear the current geophysical alert message by telephone, dial (303) 497-3235. Inquiries regarding these messages should be addressed to:Space Weather Operations
Boulder, CO 80305-3328
Marine storm warnings are broadcast for the Atlantic and Pacific oceans and the Gulf of Mexico. The National Weather Service provides the storm warning information. Atlantic highseas warnings are broadcast by WWV at 8 and 9 minutes after the hour, and a Pacific highseas warning is broadcast at 10 minutes after the hour. WWVH broadcasts a Pacific highseas warning at 48, 49, 50 and 51 minutes after the hour. Additional segments (at 11 minutes after the hour on WWV and at 52 minutes after the hour on WWVH) are used if there are unusually widespread storm conditions. The brief voice messages warn mariners of storm threats present in their areas.
The storm warnings are based on the most recent forecasts. The forecasts are updated at 0500, 1100, 1700, and 2300 UTC for WWV; and at 0000, 0600, 1200, and 1800 UTC for WWVH. All marine forecasts rely heavily on the Voluntary Observing Ship (VOS) program for obtaining meteorological observations.
Here is the text of a typical storm warning announcement:
North Atlantic weather West of 35 West at 1700 UTC; Hurricane Donna, intensifying, 24 North, 60 West, moving northwest, 20 knots, winds 75 knots; storm, 65 North, 35 West, moving east, 10 knots; winds 50 knots, seas 15 feet.For more information about marine storm warnings, write to: National Weather Service, NOAA, 1325 East West Highway, Silver Spring, MD 20910. Or, visit the National Weather Service web site.
The United States Coast Guard sponsors two voice announcements per hour on WWV and WWVH, giving current status information about the GPS satellites and related operations. The 40-s announcements begin at 14 and 15 after each hour on WWV and at 43 and 44 minutes after each hour on WWVH. The announcement can be heard by telephone by dialing (703) 313-5907. For further information, contact the U.S. Coast Guard Navigation Center, 7323 Telegraph Road, Alexandria, VA 22310, or call (703) 313-5900.
WWVH uses a female voice (Jane Barbe) to distinguish itself from WWV, which uses a male voice. WWVH time signals can also be accessed by telephone.Is WWV still transmitting? ›
NIST radio station WWV broadcasts time and frequency information 24 hours per day, 7 days per week to millions of listeners worldwide.What is the accuracy of WWV? ›
When I listen to WWV or WWVH, how accurate is the time? The time is kept to within less than 0.0001 milliseconds of Coordinated Universal Time (UTC) at the transmitter site, but the signal is delayed as it travels from the radio station to your location.What tone frequency is WWV? ›
Both WWV and WWVH broadcast standard frequency audio tones that alternate during most minutes of the hour. Most minutes feature a 500 or 600 Hz audio tone. However, a 440 Hz tone is broadcast once per hour, and some minutes do not include any audio tones at all.What frequencies does WWVB use? ›
WWVB broadcasts on a frequency of 60 kHz. Your radio controlled clock actually has a miniature radio receiver inside, which is permanently tuned to receive the 60 kHz signal. The 60 kHz signal is located in a part of the radio spectrum called LF, which stands for low frequency.What is NIST most accurate clock? ›
The nation's primary frequency standard is a cesium fountain atomic clock developed at the NIST laboratories in Boulder, Colorado.How can I listen to WWV? ›
National Weather Service Products via WWV, WWVH HF Voice
The audio portions of the WWV and WWVH broadcasts can also be heard by telephone. To hear these broadcasts, dial (303) 499-7111 for WWV (Colorado), and (808) 335-4363 for WWVH (Hawaii). Callers are disconnected after 2 minutes.
The WWVB radio station radiates a 50kW signal that operates at a 60kHz carrier frequency  .Does long wave radio still exist? ›
It will also continue to be broadcast via HM Coastguard's channels. The Daily Service and the longer version of Yesterday in Parliament will also continue on LW until March 2024 and will then be available on BBC Radio 4 Extra and BBC Sounds.How accurate is the NIST atomic clock? ›
One of these clocks, the strontium atomic clock, is accurate to within 1/15,000,000,000 of a second per year. This is so accurate that it would not have gained or lost a second if the clock had started running at the dawn of the universe.
The primary standard for the United States, the National Institute of Standards and Technology (NIST)'s caesium fountain clock named NIST-F2, measures time with an uncertainty of 1 second in 300 million years (relative uncertainty 10−16).Are radio controlled clocks accurate? ›
Radio clocks synchronized to a terrestrial time signal can usually achieve an accuracy within a hundredth of a second relative to the time standard, generally limited by uncertainties and variability in radio propagation.What frequencies do military comms use? ›
The primary HFGCS voice frequencies are 4724.0 kHz, 8992.0 kHz, 11175.0 kHz, and 15016.0 kHz. In addition to the HFGCS, U.S. aircraft frequently use Military Auxiliary Radio System (MARS) HF stations (13927.0 kHz) and Canadian Forces HF stations (11232.0 kHz) to relay messages.What is a WWV receiver? ›
WWV transmits frequency reference standards and time code information. The transmitted time code is referenced to a Cesium clock with a timing accuracy of 10 microseconds and a frequency accuracy of 1 part in 100 billion.What time zone is WWVB? ›
While most time signals encode the local time of the broadcasting nation, the United States spans multiple time zones, so WWVB broadcasts the time in Coordinated Universal Time (UTC).What radio frequencies does the US government use? ›
|225.0-328.6 MHz||960.0-1164.0 MHz||1710.0-1755.0 MHz|
|399.9-400.05 MHz||1240.0-1300.0 MHz||2000.0-2020.0 MHz|
|400.05-400.15 MHz||1300.0-1350.0 MHz||2020.0-2025.0 MHz|
|400.15-401.0 MHz||1350.0-1390.0 MHz||2025.0-2110.0 MHz|
|401.0-402.0 MHz||1390.0-1392.0 MHz||2110.0-2120.0 MHz|
NIST radio station WWVB is located near Fort Collins, Colorado.What is the most common NIST standard? ›
One of the most widely used NIST security standard is the NIST Cybersecurity Framework (CSF). This internationally recognized framework offers voluntary guidance, based on existing standards, guidelines, and practices for organizations to better manage and reduce cybersecurity risk.What is the difference between NIST 800 37 and 53? ›
SP 800-53 works alongside SP 800-37, which was developed to provide federal agencies and contractors with guidance on implementing risk management programs. SP 800-53 focuses on the controls which can be used along with the risk management framework outlined in 800-37.What is the most common NIST framework? ›
NIST SP 800-53 is the information security benchmark for U.S. government agencies and is widely used in the private sector.
Radio Garden allows you to listen to thousands of live radio stations world wide by rotating the globe. Every green dot represents a city or town. Tap on it to tune into the radio stations broadcasting from that city.Is there an app to listen to global radio stations? ›
Global Player is completely free to download and use. It's available on your smart speaker (e.g. “play Capital”), iOS or Android device and at globalplayer.com Just sign in and enjoy!What frequency is the time signal? ›
WWV disseminates the official U.S. Government time signals. The transmitter broadcasts on five frequencies: 2.5 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz.Is 80% signal strength good? ›
-80 dBm: This is an unreliable signal strength. You may be able to connect to your network, but you will not support most online activity. -90 dBm: This is a bad signal strength. You are not likely to connect to internet at this level.How can I boost my atomic clock signal? ›
Atomic clocks have antennas that are directional and reception may be improved by turning the antenna to increase signal strength. Place the radio controlled clock along a wall or near a window that faces towards Fort Collins.Which signal strength is best? ›
Signal strengths can range from approximately -30 dBm to -110 dBm. The closer that number is to 0, the stronger the cell signal. In general, anything better than -85 decibels is considered a usable signal.What is the longest running radio station in the United States? ›
world's first commercial radio station, KDKA, began broadcasting in Pittsburgh in 1920.Why are short wave radios not used anymore? ›
“AM broadcasting is expensive, and, since the end of the Cold War, many Western governments don't see the need to spend large amounts on transmitting their output on shortwave,” said Sennitt. “As a result, some have closed down their shortwave services altogether.What is USA longest running radio? ›
The Grand Ole Opry is the longest-running live radio program in the world.Is there anything more accurate than an atomic clock? ›
Atomic clocks are so accurate that they will lose one second approximately every 100 million years; for reference, the average quartz clock will lose one second every couple of years. On the other hand, Ye's optical lattice clock will lose one second every 15 billion years, making it the world's most accurate clock.
Since the atomic clock is updated at least once each day, any error would be measured in fractions of a second, and the display would still appear to be on the correct second.Are atomic clocks perfect? ›
By measuring the oscillation of atoms, atomic clocks remain precise, but they're not perfect. They experience an error of 1 second every one-hundred million years or so. Today, the NIST-F1 atomic clock in Colorado is considered to be one of the most precise clocks in the world. It is called a cesium fountain clock.What is the doomsday clock closest ever? ›
The "100 seconds to midnight" setting remained unchanged in 2021 and 2022. On January 24, 2023, the Clock was moved to 90 seconds (1 minute, 30 seconds) before midnight, meaning that the Clock's current setting is the closest it has ever been to midnight since its inception in 1947.What is the most accurate time on Earth? ›
The world's most precise clock is found in the United States. The clock was built by the National Institute of Standard and Technology together with the University of Colorado, Boulder. The clock is so precise no second is lost over the entire age of the Universe.What is the name of the most accurate clock in the world? ›
- The most precise form of clock ever created is the cesium atomic clock.
- This gadget uses transitions between the spinning states of the cesium nucleus to provide a frequency that is so consistent that it has been utilized to create the time standard.
Try moving your clock to a different location. Objects such as televisions, electric motors and fluorescent lights can interfere with the signal. A steel-framed or reinforced concrete building, or large metal objects such as metallic window frames, will reduce the signal inside.Why does my radio controlled clock keep changing the time? ›
This is to conserve the battery, as the reception unit takes more power than the clock/watch mechanism. So some radio-controlled clocks or watches may not 'realise' that the time has changed until an hour or more later. How long will a battery last in my clock/watch?What is the advantage of radio controlled clock? ›
The time from the atomic clock is then broadcast by low-frequency radio waves that are stable enough to travel 1000 miles from its origin and follow the curvature of the Earth. The radio-controlled clock picks up these signals with its antennae and can keep precision time with the world's most accurate clocks.What radios do US soldiers use? ›
The Rifleman Radio is a lightweight, rugged, handheld radio that transmits voice and data via the Soldier Radio Waveform (SRW). The Rifleman Radio acts as its own router and is not dependent on fixed infrastructures, such as cell phone towers or line-of-sight communications.What radio does the US Army use? ›
Single Channel Ground and Airborne Radio System (SINCGARS) is a high frequency combat-net radio (CNR) used by U.S. and allied military forces. In the CNR network, the SINCGARS' primary role is voice transmission between surface and airborne command and control assets.
Manpack radios are communications systems that are compact and lightweight enough to be carried by a single operator, typically in a backpack. Military manpack radios are used by a wide range of forces and operators, including infantry, special forces, and naval and air force personnel.When did WWV start? ›
WWV began broadcasting in May 1920 from Washington, D.C., at a frequency of 600 kilohertz. The first broadcasts were Friday evening music concerts that lasted from 8:30 to 11. The 50-watt signal could be heard about 40 kilometers away.What is WWV used for? ›
WWV is a shortwave ("high frequency" or HF) radio station, located near Fort Collins, Colorado. It has broadcast a continuous time signal since 1945, and implements United States government frequency standards, with transmitters operating on 2.5, 5, 10, 15, and 20 MHz.What is the meaning of WWV? ›
World Wide Video. WWV. [radio call sign for ] National Institute of Standards and Technology Time & Frequency shortwave radio station.What is the difference between atomic and radio controlled clocks? ›
A radio clock or radio-controlled clock (RCC), and often (incorrectly) referred to as an atomic clock is a type of quartz clock or watch that is automatically synchronized to a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock.What is a WWVB search? ›
WWVB is a time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST). Most radio-controlled clocks in North America use WWVB's transmissions to set the correct time.Where is WWVH located? ›
NIST radio station WWVH broadcasts time and frequency information 24 hours per day, 7 days per week to listeners worldwide. The station is located on the Island of Kauai, Hawaii on a 12 hectare (30 acre) site near Kekaha at Kokole Point.What frequency is the atomic clock shortwave? ›
The DCF77 radio signals are derived from an atomic clock, and broadcasted on 77.5 kHz. The signal can be received up to a distance of 2000 km and more.What is time signal on radio? ›
The signal operates on a frequency of 60 kHz and carries a time and date code that can be received and decoded by a wide range of readily-available radio-controlled clocks.How do I listen to WWV? ›
WWV is also the world's longest continuously-broadcasting radio station. (NIST doesn't stream the stations online because signals are often delayed as they stream over the internet. But you can hear the stations by calling (303) 499-7111 for WWV or (808) 335-4363 for WWVH .
WWVB began operation as radio station KK2XEI in July 1956. This experimental station was operated from 1530 to 2000 hours universal time each working day from Boulder, Colorado. The continuous wave 60 kHz signal was not modulated, except for a call sign ID that was sent every 20 minutes.Is atomic clock the most accurate? ›
With an error of only 1 second in up to 100 million years, atomic clocks are among the most accurate timekeeping devices in history.What are the three types of atomic clock? ›
Three commonly used types of atomic clock are the cesium atomic beam, the hydrogen maser, and the rubidium gas cell. The cesium clock has high accuracy and good long-term stability. The hydrogen maser has the best stability for periods of up to a few hours.