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WWVH antenna field WWVH antenna field.jpg
WWVH antenna field

WWVH is the callsign of the U.S. National Institute of Standards and Technology's shortwave radio time signal station in Kekaha, on the island of Kauai in the state of Hawaii. Coordinates: 21°59′16″N159°45′47″W / 21.98778°N 159.76306°W / 21.98778; -159.76306

The National Institute of Standards and Technology (NIST) is a physical sciences laboratory, and a non-regulatory agency of the United States Department of Commerce. Its mission is to promote innovation and industrial competitiveness. NIST's activities are organized into laboratory programs that include nanoscale science and technology, engineering, information technology, neutron research, material measurement, and physical measurement.

Radio Technology of using radio waves to carry information

Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by a radio receiver connected to another antenna. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking and satellite communication among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location. In radio navigation systems such as GPS and VOR, a mobile receiver receives radio signals from navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In wireless radio remote control devices like drones, garage door openers, and keyless entry systems, radio signals transmitted from a controller device control the actions of a remote device.

Time signal indication of time of day

A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.


WWVH is the Pacific sister station to WWV, and has a similar broadcast format. Like WWV, WWVH's main function is the dissemination of official U.S. Government time, through exactly the same methods as found on WWV's signal.

WWV (radio station) Shortwave radio station broadcasting time signals

WWV is a shortwave radio station, located near Fort Collins, Colorado. It is best known for its continuous time signal broadcasts begun in 1945, and is also used to establish official United States government frequency standards, with transmitters operating on 2.5, 5, 10, 15, and 20 MHz. WWV is operated by U.S. National Institute of Standards and Technology (NIST), under the oversight of its Time and Frequency Division, which is part of NIST's Physical Measurement Laboratory based in Gaithersburg, Maryland.

To minimize interference with the WWV broadcasts on the same frequencies, WWVH's broadcasts on 5, 10 and 15 MHz are directional, pointed primarily west. Despite this strategy, in certain places, particularly on the west coast of North America; and at certain times, due to ionospheric conditions, the listener can actually hear both WWV and WWVH on the same frequency at the same time. The information modulated on the carrier is modified to reduce confusion if both are received simultaneously. In particular, voice announcements on one correspond to silent periods on the other. WWVH uses a female voice to distinguish itself from WWV, which uses a male voice. WWVH time signals can also be accessed by telephone.

Ionosphere The ionized part of Earths upper atmosphere

The ionosphere is the ionized part of Earth's upper atmosphere, from about 60 km (37 mi) to 1,000 km (620 mi) altitude, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. The region below the ionosphere is called neutral atmosphere, or neutrosphere.

NIST Time Signal Station Services [1]
in service
Year out
of service
WWV 1923
WWVB 1963

Transmission system

WWVH antenna coordinates [2]
2.5 MHz 21°59′20.9″N159°45′52.4″W / 21.989139°N 159.764556°W / 21.989139; -159.764556
5 MHz 21°59′10.8″N159°45′44.8″W / 21.986333°N 159.762444°W / 21.986333; -159.762444
10 MHz 21°59′18.2″N159°45′51.3″W / 21.988389°N 159.764250°W / 21.988389; -159.764250
15 MHz 21°59′15.3″N159°45′50.0″W / 21.987583°N 159.763889°W / 21.987583; -159.763889

WWVH broadcasts its signal on four transmitters, one for each frequency. The 2.5 MHz transmitter puts out an ERP of 5 kW, while the other transmitters use 10 kW of ERP. The 2.5 MHz antenna is one half-wavelength tall, and radiates in an omnidirectional pattern. The remaining antennas each consist of two elements one half-wavelength tall and horizontally separated by one quarter-wavelength. The signal radiating from one element is in quadrature phase with respect to the signal from the other. This results in a cardioid radiation pattern with a maximum gain directed west.

Effective radiated power (ERP), synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter. It is the total power in watts that would have to be radiated by a half-wave dipole antenna to give the same radiation intensity as the actual source at a distant receiver located in the direction of the antenna's strongest beam. ERP measures the combination of the power emitted by the transmitter and the ability of the antenna to direct that power in a given direction. It is equal to the input power to the antenna multiplied by the gain of the antenna. It is used in electronics and telecommunications, particularly in broadcasting to quantify the apparent power of a broadcasting station experienced by listeners in its reception area.

Wavelength spatial period of the wave—the distance over which the waves shape repeats, and thus the inverse of the spatial frequency

In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. The inverse of the wavelength is called the spatial frequency. Wavelength is commonly designated by the Greek letter lambda (λ). The term wavelength is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids.

Cardioid type of curve

A cardioid is a plane curve traced by a point on the perimeter of a circle that is rolling around a fixed circle of the same radius. It can also be defined as an epicycloid having a single cusp. It is also a type of sinusoidal spiral, and an inverse curve of the parabola with the focus as the center of inversion.

Broadcast format

Recording of WWVH from 4:58:43 to 5:03:08 UTC on March 16, 2015.
WWV-WWVH time code format.svg

The WWVH signal is extremely similar to the WWV signal, but some changes have been made to reduce confusion if both are heard at once: [2]

Jane Barbe American singer

Jane Barbe was an American voice actress and singer. She was known as the "Time Lady" for the recordings she made for the Bell System and other phone companies. The ubiquity of her recordings eventually made her a pop-culture figure, and her death drew national attention.

Half-hourly station identification announcement

WWVH identifies itself twice each hour, at 29 and 59 minutes past the hour. The text of the identification is as follows:

Reception reports sent to that address will on request be answered with a QSL card. [3]

Telephone service

WWVH's time signal can also be accessed by calling +1 (808) 335-4363. [4]

See also

Related Research Articles

Shortwave radio radio frequencies in the range of 1.6-30 megahertz (ITU region 1) or 1.7-30 megahertz (ITU region 2)

Shortwave radio is radio transmission using shortwave radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), and generally extends from 3–30 MHz ; above the medium frequency band (MF), to the end of the HF band.

Radio clock type of clock which self-synchronizes its time using dedicated radio transmitters

A radio clock or radio-controlled clock (RCC) is a 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. Such a clock may be synchronized to the time sent by a single transmitter, such as many national or regional time transmitters, or may use the multiple transmitters used by satellite navigation systems such as GPS. Such systems may be used to automatically set clocks or for any purpose where accurate time is needed. RC clocks may include any feature available for a clock, such as alarm function, display of ambient temperature and humidity, broadcast radio reception, etc.

Time from NPL (MSF)

The Time from NPL is a radio signal broadcast from the Anthorn Radio Station near Anthorn, Cumbria, which serves as the United Kingdom's national time reference. The time signal is derived from three atomic clocks installed at the transmitter site, and is based on time standards maintained by the UK's National Physical Laboratory (NPL) in Teddington. The service is provided by Babcock International, under contract to the NPL. It was funded by the former Department for Business, Innovation and Skills; as of 2017 NPL Management Limited (NPLML) was owned by the Department for Business, Energy and Industrial Strategy (BEIS), and NPL operated as a public corporation.

CHU is the call sign of a shortwave time signal radio station operated by the Institute for National Measurement Standards of the National Research Council of Canada.

Radio VNG was Australia's national time signal service. It was inaugurated by the Australian Post Office at Lyndhurst, Victoria on 21 September 1964, although a predecessor service using the callsign VLX had begun in March 1946 alongside shortwave radio station VLR. From 1964 until 1987, Radio VNG transmitted on 4.5, 7.5 and 12 MHz from the Lyndhurst transmitters. After 1987 it relocated to Shanes Park, NSW, and transmitted on 2.5, 5, 8.638, 12.984, and 16 MHz.

BPM is the call sign of the official short-wave time signal service of the People's Republic of China, operated by the Chinese Academy of Sciences, broadcasting from CAS's National Time Service Center in Pucheng County, Shaanxi at 34°56′55.96″N109°32′34.93″E, roughly 70 km northeast of Lintong, along with NTSC's long-wave time signal BPL on 100 kHz.

WWVB Radio station

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. The 70 kW ERP signal transmitted from WWVB is a continuous 60 kHz carrier wave, the frequency of which is derived from a set of atomic clocks located at the transmitter site, yielding a frequency uncertainty of less than 1 part in 1012. A one-bit-per-second time code, which is based on the IRIG "H" time code format and derived from the same set of atomic clocks, is then modulated onto the carrier wave using pulse-width modulation and amplitude-shift keying. A single complete frame of time code begins at the start of each minute, lasts one minute, and conveys the year, day of year, hour, minute, and other information as of the beginning of the minute.

RWM is the callsign of a high frequency (shortwave) standard frequency and time signal radio station in Moscow, Russia. It is controlled by All-Russian Scientific Research Institute for Physical-Engineering and Radiotechnical Metrology, and operated by Russian Television and Radio Broadcasting Network. Transmitting frequencies are 4.996 MHz with 5 kW and on 9.996 and 14.996 MHz with 8 kW.

JJY is the call sign of a low frequency time signal radio station located in Japan.

DCF77 German longwave time signal and standard-frequency radio station

DCF77 is a German longwave time signal and standard-frequency radio station. It started service as a standard-frequency station on 1 January 1959. In June 1973 date and time information was added. Its primary and backup transmitter are located at 50°0′56″N9°00′39″E in Mainflingen, about 25 km south-east of Frankfurt am Main, Germany. The transmitter generates a nominal power of 50 kW, of which about 30 to 35 kW can be radiated via a T-antenna.

A440 (pitch standard) pitch standard

A440 or A4, which has a frequency of 440 Hz, is the musical note of A above middle C and serves as a general tuning standard for musical pitch.


YVTO is the callsign of the official time signal from the Juan Manuel Cagigal Naval Observatory in Caracas, Venezuela. The content of YVTO's signal, which is a continuous 1 kW amplitude modulated carrier wave at 5.000 MHz, is much simpler than that broadcast by some of the other time signal stations around the world, such as WWV.

Inter-range instrumentation group time codes, commonly known as IRIG time codes, are standard formats for transferring timing information. Atomic frequency standards and GPS receivers designed for precision timing are often equipped with an IRIG output. The standards were created by the Tele Communications Working Group of the U.S. military's Inter-Range Instrumentation Group (IRIG), the standards body of the Range Commanders Council. Work on these standards started in October 1956, and the original standards were accepted in 1960.

Beta is a time signal service in the VLF range in Russia, operated by the Russian Navy. It is controlled by All-Russian Scientific Research Institute for Physical-Engineering and Radiotechnical Metrology. There are 6 transmitter stations, which take turns transmitting time signals and other communications.

Yosemite Sam is the nickname given by DXers to a number station that first surfaced on December 19, 2004. It transmits on several shortwave frequencies in dual side band: 3700 kHz, 4300 kHz, 6500 kHz, and 10500 kHz. The nickname is taken from the Looney Tunes character Yosemite Sam, whose voice is played as part of the unusual transmission.

TDF time signal

TéléDiffusion de France broadcast the TDF time signal, controlled by LNE–SYRTE, from the Allouis longwave transmitter at 162 kHz, with a power of 2 MW.

HLA is a time signal radio station in Daejeon, South Korea, operated by the Korea Research Institute of Standards and Science. Established on November 24, 1984, it transmits a 2 kW signal on 5 MHz (±0.01 Hz). Originally only transmitted for 7 hours per day (01:00–08:00), 5 days per week (M–F), it is continuous as of 2011. There are over 100 users of the signal in Korea.

​JN53dv is the Maidenhead grid square of an experimental shortwave time signal station in Italy. It is located in the town of Corsanico-Bargecchia near Massarosa and operated by Italcable

BSF is the callsign of the time signal transmitter for Taiwan, which transmits time information on 77.5 kHz in the longwave range, and 5 MHz & 15 MHz in the shortwave range from Chung-Li. The longwave transmitter, which uses a T-antenna is situated at 25°0′20″N121°21′54″E.
Due to "low demand", the short wave of BSF was discontinued as of July 1, 2004. The time signal is currently transmitted at a low frequency of 77.5 kHz


  1. "NBS Miscellaneous Publication 236 (1967 edition): NBS Standard Frequency and Time Services" (PDF).
  2. 1 2 Nelson, Glenn; Michael Lombardi; Dean Okayama (2005). NIST Special Publication 250-67: NIST Time and Frequency Stations: WWV, WWVH and WWVB (PDF). NIST. Archived from the original (PDF) on January 25, 2017. Retrieved January 26, 2017.
  3. QSL Gallery for NIST Radio Stations Archived September 11, 2017, at the Wayback Machine
  4. Lombardi, Michael A. (September 24, 2009). "Telephone Time-of-Day Service". NIST. Retrieved July 3, 2019.
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