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 1.7–30 MHz (176.3–10.0 m); from the high end of the medium frequency band (MF) just above the mediumwave AM broadcast band, to the end of the HF band.
Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or "skip" propagation. Thus shortwave radio can be used for very long distance communication, in contrast to radio waves of higher frequency which travel in straight lines (line-of-sight propagation) and are limited by the visual horizon, about 64 km (40 miles). Shortwave radio is used for broadcasting of voice and music to shortwave listeners over very large areas; sometimes entire continents or beyond. It is also used for military over-the-horizon radar, diplomatic communication, and two-way international communication by amateur radio enthusiasts for hobby, educational and emergency purposes, as well as for long distance aviation and marine communications.
The widest popular definition of the shortwave frequency interval is the ITU Region 1 (EU+Africa+Russia...) definition, and is the span 1.6–30 MHz, just above the medium wave band, which ends approximately at 1.6 MHz.
There are also other definitions of the shortwave frequency interval:
The name "shortwave" originated during the early days of radio in the early 20th century, when the radio spectrum was considered divided into long wave (LW), medium wave (MW) and short wave bands based on the wavelength of the radio waves. Shortwave radio received its name because the wavelengths in this band are relatively shorter than 200 m (1,500 kHz) which marked the original upper limit of the medium frequency band first used for radio communications. The broadcast medium wave band now extends above the 200 m/1,500 kHz limit, and the amateur radio 1.8 MHz – 2.0 MHz band (known as the "top band") is the lowest-frequency band considered to be 'shortwave'.
Early long distance radio telegraphy used long waves, below 300 kilohertz (kHz). The drawbacks to this system included a very limited spectrum available for long distance communication, and the very expensive transmitters, receivers and gigantic antennas that were required. It was also difficult to beam the radio wave directionally with long wave, resulting in a major loss of power over long distances. Prior to the 1920s, the shortwave frequencies above 1.5 MHz were regarded as useless for long distance communication and were designated in many countries for amateur use.
Guglielmo Marconi, pioneer of radio, commissioned his assistant Charles Samuel Franklin to carry out a large scale study into the transmission characteristics of short wavelength waves and to determine their suitability for long distance transmissions. Franklin rigged up a large antenna at Poldhu Wireless Station, Cornwall, running on 25 kW of power. In June and July 1923, wireless transmissions were completed during nights on 97 meters from Poldhu to Marconi's yacht Elettra in the Cape Verde Islands.
In September 1924, Marconi transmitted daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut. Franklin went on to refine the directional transmission, by inventing the curtain array aerial system. In July 1924, Marconi entered into contracts with the British General Post Office (GPO) to install high speed shortwave telegraphy circuits from London to Australia, India, South Africa and Canada as the main element of the Imperial Wireless Chain. The UK-to-Canada shortwave "Beam Wireless Service" went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa and India went into service in 1927.
Shortwave communications began to grow rapidly in the 1920s, similar to the internet in the late 20th century. By 1928, more than half of long distance communications had moved from transoceanic cables and longwave wireless services to shortwave and the overall volume of transoceanic shortwave communications had vastly increased. Shortwave stations had cost and efficiency advantages over massive longwave wireless installations, however some commercial longwave communications stations remained in use until the 1960s. Long distance radio circuits also reduced the load on the existing transoceanic telegraph cables and hence the need for new cables, although the cables maintained their advantages of high security and a much more reliable and better quality signal than shortwave.
The cable companies began to lose large sums of money in 1927, and a serious financial crisis threatened the viability of cable companies that were vital to strategic British interests. The British government convened the Imperial Wireless and Cable Conference in 1928 "to examine the situation that had arisen as a result of the competition of Beam Wireless with the Cable Services". It recommended and received Government approval for all overseas cable and wireless resources of the Empire to be merged into one system controlled by a newly formed company in 1929, Imperial and International Communications Ltd. The name of the company was changed to Cable and Wireless Ltd. in 1934.
Long-distance cables had a resurgence beginning in 1956 with the laying of TAT-1 across the Atlantic Ocean, the first voice frequency cable on this route. This provided 36 high quality telephone channels and was soon followed by even higher capacity cables all around the world. These sounded the death knell of shortwave radio for commercial communications.
Amateur radio operators also discovered that long-distance communication was possible on shortwave bands. Early long-distance services used surface wave propagation at very low frequencies, which are attenuated along the path at wavelengths shorter than 1,000 meters. Longer distances and higher frequencies using this method meant more signal loss. This, and the difficulties of generating and detecting higher frequencies, made discovery of shortwave propagation difficult for commercial services.
Radio amateurs may have conducted the first successful transatlantic tests in December 1921, operating in the 200 meter mediumwave band (near 1,500 kHz in the modern AM broadcast band) – the shortest wavelength then available to amateurs. In 1922 hundreds of North American amateurs were heard in Europe on 200 meters and at least 20 North American amateurs heard amateur signals from Europe. The first two-way communications between North American and Hawaiian amateurs began in 1922 at 200 meters. Although operation on wavelengths shorter than 200 meters was technically illegal (but tolerated as the authorities mistakenly believed at first that such frequencies were useless for commercial or military use), amateurs began to experiment with those wavelengths using newly available vacuum tubes shortly after World War I.
Extreme interference at the longer edge of the 150–200 meter band – the official wavelengths allocated to amateurs by the Second National Radio Conference in 1923 – forced amateurs to shift to shorter and shorter wavelengths; however, amateurs were limited by regulation to wavelengths longer than 150 meters (2 MHz). A few fortunate amateurs who obtained special permission for experimental communications at wavelengths shorter than 150 meters completed hundreds of long distance two way contacts on 100 meters (3 MHz) in 1923 including the first transatlantic two way contacts.
By 1924 many additional specially licensed amateurs were routinely making transoceanic contacts at distances of 6,000 miles (9,600 km) and more. On 21 September 1924 several amateurs in California completed two-way contacts with an amateur in New Zealand. On 19 October amateurs in New Zealand and England completed a 90 minute two-way contact nearly halfway around the world. On 10 October the Third National Radio Conference made three shortwave bands available to U.S. amateurs at 80 meters (3.75 MHz), 40 meters (7 MHz) and 20 meters (14 MHz). These were allocated worldwide, while the 10 meter band (28 MHz) was created by the Washington International Radiotelegraph Conference on 25 November 1927. The 15 meter band (21 MHz) was opened to amateurs in the United States on 1 May 1952.
Shortwave radio frequency energy is capable of reaching any location on the Earth as it is influenced by ionospheric reflection back to the earth by the ionosphere, (a phenomenon known as "skywave propagation"). A typical phenomenon of shortwave propagation is the occurrence of a skip zone where reception fails. With a fixed working frequency, large changes in ionospheric conditions may create skip zones at night.
As a result of the multi-layer structure of the ionosphere, propagation often simultaneously occurs on different paths, scattered by the E or F region and with different numbers of hops, a phenomenon that may be disturbed for certain techniques. Particularly for lower frequencies of the shortwave band, absorption of radio frequency energy in the lowest ionospheric layer, the D layer, may impose a serious limit. This is due to collisions of electrons with neutral molecules, absorbing some of a radio frequency's energy and converting it to heat. Predictions of skywave propagation depend on:
Several different types of modulation are used to incorporate information in a short-wave signal.
Amplitude modulation is the simplest type and the most commonly used for shortwave broadcasting. The instantaneous amplitude of the carrier is controlled by the amplitude of the signal (speech, or music, for example). At the receiver, a simple detector recovers the desired modulation signal from the carrier.
Single sideband transmission is a form of amplitude modulation but in effect filters the result of modulation. An amplitude-modulated signal has frequency components both above and below the carrier frequency. If one set of these components is eliminated as well as the residual carrier, only the remaining set is transmitted. This reduces power in the transmission, as roughly 2⁄3 of the energy sent by an AM signal is in the “carrier”, which is not needed to recover the information contained in the signal. It also reduces signal bandwidth, enabling less than one-half the AM signal bandwidth to be used.
The drawback is the receiver is more complicated, since it must re-create the carrier to recover the signal. Small errors in the detection process greatly affect the pitch of the received signal. As a result, single sideband is not used for music or general broadcast. Single sideband is used for long-range voice communications by ships and aircraft, Citizen's Band, and amateur radio operators. Lower sideband (LSB) is customarilly used below 9 MHz and USB (upper sideband) above 9 MHz.
Vestigal sideband transmits the carrier and one complete sideband, but filters out the other sideband. It is a compromise between AM and SSB, enabing simple receivers to be used, but requires almost as much transmitter power as AM. One advantage is only half the bandwidth of an AM signal is used. It can be heard in the transmission of certain radio time signal stations. Vestigial sideband is used for over the air Television Broadcasts both analog and digital.
Narrow-band frequency modulation (NBFM or NFM) is used typically above 20 MHz. Because of the larger bandwidth required, NBFM is commonly used for VHF communication. Regulations limit the bandwidth of a signal transmitted in the HF bands, and the advantages of frequency modulation are greatest if the FM signal has a wide bandwidth. NBFM is limited to short-range transmissions due to the multiphasic distortions created by the ionosphere.
Digital Radio Mondiale (DRM) is a digital modulation for use on bands below 30 MHz. It is a digital signal, like the data modes, below, but is for transmitting audio, like the analog modes above.
Continuous wave (CW) is on-and-off keying of a carrier, used for Morse code communications and Hellschreiber facsimile-based teleprinter transmissions. It is a data mode, although often listed separately.
Radioteletype, fax, digital, slow-scan television, and other systems use forms of frequency-shift keying or audio subcarriers on a shortwave carrier. These generally require special equipment to decode, such as software on a computer equipped with a sound card.
Note that on modern computer-driven systems, digital modes are typically sent by coupling a computer's sound output to the SSB input of a radio.
Some established users of the shortwave radio bands may include:
Sporadic or non-traditional users of the shortwave bands may include:
See International broadcasting for details on the history and practice of broadcasting to foreign audiences.
See Shortwave relay station for the actual kinds of integrated technologies used to bring high power signals to listeners.
The World Radiocommunication Conference (WRC), organized under the auspices of the International Telecommunication Union, allocates bands for various services in conferences every few years. The last WRC took place in 2007.
At WRC-97 in 1997, the following bands were allocated for international broadcasting. AM shortwave broadcasting channels are allocated with a 5 kHz separation for traditional analog audio broadcasting.
|Metre Band||Frequency Range||Remarks|
|120 m||2.3–2.495 MHz||tropical band|
|90 m||3.2–3.4 MHz||tropical band|
|75 m||3.9–4 MHz||shared with the North American amateur radio 80m band|
|60 m||4.75–5.06 MHz||tropical band|
|49 m||5.9–6.2 MHz|
|41 m||7.2–7.6 MHz||shared with the amateur radio 40m band|
|31 m||9.4–9.9 MHz||currently the most heavily used band|
|25 m||11.6–12.2 MHz|
|22 m||13.57–13.87 MHz|
|19 m||15.1–15.8 MHz|
|16 m||17.48–17.9 MHz|
|15 m||18.9–19.02 MHz||almost unused, could become a DRM band|
|13 m||21.45–21.85 MHz|
|11 m||25.6–26.1 MHz||may be used for local DRM broadcasting|
Although countries generally follow the table above, there may be small differences between countries or regions. For example, in the official bandplan of the Netherlands, the 49 m band starts at 5.95 MHz, the 41 m band ends at 7.45 MHz, the 11 m band starts at 25.67 MHz, and the 120, 90 and 60 m bands are absent altogether. Additionally, international broadcasters sometimes operate outside the normal WRC-allocated bands or use off-channel frequencies. This is done for practical reasons, or to attract attention in crowded bands (60m, 49m, 40m, 41m, 31m, 25m).
The new digital audio broadcasting format for shortwave DRM operates 10 kHz or 20 kHz channels. There are some ongoing discussions with respect to specific band allocation for DRM, as it mainly transmitted in 10 kHz format.
The power used by shortwave transmitters ranges from less than one watt for some experimental and amateur radio transmissions to 500 kilowatts and higher for intercontinental broadcasters and over-the-horizon radar. Shortwave transmitting centers often use specialized antenna designs (like the ALLISS antenna technology) to concentrate radio energy at the target area.
Shortwave does possess a number of advantages over newer technologies, including the following:
Shortwave radio's benefits are sometimes regarded as being outweighed by its drawbacks, including:
The Asia-Pacific Telecommunity estimates that there are approximately 600 million shortwave broadcast-radio receivers in use in 2002. WWCR claims that there are 1.5 billion shortwave receivers worldwide.
Many hobbyists listen to shortwave broadcasters. In some cases, the goal is to hear as many stations from as many countries as possible (DXing); others listen to specialized shortwave utility, or "ute", transmissions such as maritime, naval, aviation, or military signals. Others focus on intelligence signals from numbers stations, stations which transmit strange broadcast usually for intelligence operations, or the two way communications by amateur radio operators. Some short wave listeners behave analogously to "lurkers" on the Internet, in that they listen only and never make any attempt to send out their own signals. Other listeners participate in clubs, or actively send and receive QSL cards, or become involved with amateur radio and start transmitting on their own.
Many listeners tune the shortwave bands for the programmes of stations broadcasting to a general audience (such as Radio Taiwan International, China Radio International, Voice of America, Radio France Internationale, BBC World Service, Voice of Korea, Radio Free Sarawak etc.). Today, through the evolution of the Internet, the hobbyist can listen to shortwave signals via remotely controlled or web controlled shortwave receivers around the world, even without owning a shortwave radio. Many international broadcasters offer live streaming audio on their websites and a number have closed their shortwave service entirely, or severely curtailed it, in favour of internet transmission.
Shortwave listeners, or SWLs, can obtain QSL cards from broadcasters, utility stations or amateur radio operators as trophies of the hobby. Some stations even give out special certificates, pennants, stickers and other tokens and promotional materials to shortwave listeners.
Some musicians have been attracted to the unique aural characteristics of shortwave radio which—due to the nature of amplitude modulation, varying propagation conditions, and the presence of interference—generally has lower fidelity than local broadcasts (particularly via FM stations). Shortwave transmissions often have bursts of distortion, and "hollow" sounding loss of clarity at certain aural frequencies, altering the harmonics of natural sound and creating at times a strange "spacey" quality due to echoes and phase distortion. Evocations of shortwave reception distortions have been incorporated into rock and classical compositions, by means of delays or feedback loops, equalizers, or even playing shortwave radios as live instruments. Snippets of broadcasts have been mixed into electronic sound collages and live musical instruments, by means of analogue tape loops or digital samples. Sometimes the sounds of instruments and existing musical recordings are altered by remixing or equalizing, with various distortions added, to replicate the garbled effects of shortwave radio reception.
The first attempts by serious composers to incorporate radio effects into music may be those of the Russian physicist and musician Léon Theremin, who perfected a form of radio oscillator as a musical instrument in 1928 (regenerative circuits in radios of the time were prone to breaking into oscillation, adding various tonal harmonics to music and speech); and in the same year, the development of a French instrument called the Ondes Martenot by its inventor Maurice Martenot, a French cellist and former wireless telegrapher. Karlheinz Stockhausen used shortwave radio and effects in works including Hymnen (1966–67), Kurzwellen (1968)—adapted for the Beethoven Bicentennial in Opus 1970 with filtered and distorted snippets of Beethoven pieces—Spiral (1968), Pole, Expo (both 1969–70), and Michaelion (1997).
Holger Czukay, a student of Stockhausen, was one of the first to use shortwave in a rock music context. In 1975, German electronic music band Kraftwerk recorded a full length concept album around simulated radiowave and shortwave sounds, entitled Radio-Activity. The The's Radio Cineola monthly broadcasts drew heavily on shortwave radio sound.
The development of direct broadcasts from satellites has reduced the demand for shortwave receiver hardware, but there are still a great number of shortwave broadcasters. A new digital radio technology, Digital Radio Mondiale (DRM), is expected to improve the quality of shortwave audio from very poor to standards comparable to the FM broadcast band. The future of shortwave radio is threatened by the rise of power line communication (PLC), also known as Broadband over Power Lines (BPL), which uses a data stream transmitted over unshielded power lines. As the BPL frequencies used overlap with shortwave bands, severe distortions can make listening to analog shortwave radio signals near power lines difficult or impossible.
Experts disagree on the future of shortwave. According to Andy Sennitt, former editor of the World Radio TV Handbook, “shortwave is a legacy technology, which is expensive and environmentally unfriendly. A few countries are hanging on to it, but most have faced up to the fact that the glory days of shortwave have gone. Religious broadcasters will still use it because they are not too concerned with listening figures".
However Thomas Witherspoon, editor of shortwave news site SWLingPost.com wrote that “shortwave remains the most accessible international communications medium that still provides listeners with the protection of complete anonymity". According to Nigel Fry, head of Distribution for the BBC World Service Group, “I still see a place for shortwave in the 21st century, especially for reaching areas of the world that are prone to natural disasters that destroy local broadcasting and Internet infrastructure".
CFRX is the international shortwave relay of CFRB, a news/talk radio station in Toronto, Ontario. It transmits with a power of 1 kilowatt on 6.07 MHz in the 49-meter shortwave band. CFRX signed on the air on February 11, 1937, 10 years after CFRB began.CFVP
CFVP is the full-time shortwave rebroadcaster of CKMX in Calgary, Alberta, Canada. CFVP broadcasts at a power of 100 watts on 6.03 MHz in the 49m shortwave band.CHU (radio station)
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.KTBN (shortwave)
KTBN (formerly known as KUSW) was the shortwave radio outlet of the Trinity Broadcasting Network, a large religious international broadcaster. The station's programming was a simulcast of the audio portion of the TBN television service.PCJ Radio
PCJ Radio (PCJ) is a private international radio station and syndicator and relay service founded in 2008 and based in Taipei, producing and transmitting programs for local and international audiences. PCJ has also distributed content via web technology since 2009. The station is owned by Canadian-born announcer and producer Keith Perron.Radio Australia
Radio Australia is the international broadcasting and online service operated by the Australian Broadcasting Corporation (ABC), Australia's public broadcaster. Most programming is in English, with some in Tok Pisin and French.
Radio Australia terminated shortwave radio broadcasting effective 31 January 2017 but continues broadcasting online and using other transmission modes such as DAB+.Radio México Internacional
Radio México Internacional is a Mexican government-run radio service based in Mexico City. It broadcast as a shortwave radio station with the broadcast callsign XERMX-OC from 1969 to 2004, and was relaunched as an Internet-only radio service in 2011. Since 1983 it has been under the control of the Instituto Mexicano de la Radio (IMER). The -OC suffix is from onda corta, Spanish for "short wave", equivalent to the -SW suffix in Canada (with none being used at all on U.S. shortwave stations).Republic Broadcasting Network
Republic Broadcasting Network (RBN) is a satellite, shortwave, and Internet radio operation based in the state of Texas. It is run by John Stadtmiller, who advertises it as a "truth radio station". In 2010, it received publicity in the news after one of its broadcasters was revealed to be a leader in the Guardians of the Free Republics, a Sovereign Citizen-affiliated group that had sent threatening letters to all 50 United States governors. The network has loose ties to the Willis Carto-founded American Free Press newspaper, which was described by political scientist George Michael as "the most important newspaper of the radical right".WBCQ (SW)
WBCQ is a shortwave radio station operating at Monticello, Maine, United States. The station is owned and operated by Allan Weiner, who also owns and operates WXME AM 780 kHz and WBCQ-FM 94.7 MHz at the shortwave site. WBCQ began operation in 1998 with just the WBCQ-1 transmitter on 7.415 MHz. WBCQ's shortwave antennas are all beamed directionally: primarily at 245 degrees, and secondarily at 65 degrees.
The station transmits numerous talk shows and other programs produced by commercial networks as well as former pirate radio broadcasters, such as Weiner himself and his erstwhile collaborators.
Unlike Weiner's former pirate radio stations, now relegated to well-documented history, WBCQ and its AM and FM sister stations are licensed by the FCC under his own name.WFLA (AM)
WFLA ("Newsradio WFLA") is talk-formatted station in Tampa, Florida, serving the Tampa Bay media market. The station is owned and operated by iHeartMedia, Inc., the largest U.S. radio station owner. The station's studios are located in South Tampa and the main transmitter site is in Town 'n' Country.WINB
WINB is a brokered Christian shortwave radio station licensed to Red Lion, Pennsylvania, in the United States. WINB began broadcasting in October 1962, making it the oldest private shortwave radio station in the United States that is still in operation.WMLK
WMLK (9.275 MHz) is a shortwave radio station in Bethel, Pennsylvania owned by the Assemblies of Yahweh. WMLK takes its name from MLK, representing three of the four consonants of the Hebrew word "malakh" (מַלְאָךְ) meaning a "messenger" or angel.WRMI
WRMI (Radio Miami International) is a shortwave radio station broadcasting from Okeechobee, Florida, United States. WRMI is a commercial radio station that sells airtime to businesses and organizations. It also relays several international news stations including Radio Ukraine International, Radio Slovakia International, Radio Tirana, Radio France International, Famagusta Gazette Radio, Radio Prague, the Italian Broadcasting Corporation, NHK World Radio Japan, and Radiodifusión Argentina al Exterior, all of which would otherwise be difficult to receive in the Western Hemisphere. It also features headline news stories from the Voice of America, several religious programs, as well as original and syndicated programs. According to its 1996 station record from the Federal Communications Commission, WRMI's broadcast target zones were the Caribbean, Central America and South America. In particular, much of its programming was targeted towards Cuba. However, as of 2016, WRMI had 23 antennas targeting many zones worldwide. Its broadcasts are also easily received in the United States and Canada. WRMI airs programs in English, Spanish, French, Portuguese, Italian,and Slovak.WRNO (shortwave)
WRNO (also known as WRNO Worldwide) is a commercial shortwave radio station which began international broadcasting on February 18, 1982 and continued regular broadcasting through the early 1990s from Metairie, Louisiana, with a continuation of periodic broadcasts starting in 2009. These call letters are still in use by the New Orleans station WRNO-FM; both were founded and originally owned by Joseph Costello III.WTWW
WTWW is a shortwave station located in Lebanon, Tennessee.
WTWW, according to their website, stands for "We Transmit World Wide".
WTWW, according to the FCC, was originally licensed a construction permit as WBWW on June 30, 2009. Testing began in January 2010 and ending mid-February 2010. Testing frequencies used were 5.755 MHz and 9.48 MHz, and recorded by several listeners who uploaded the audio to YouTube.Both the frequencies 5.755 MHz and 9.48 MHz and their transmitters were previously used by Christian shortwave outlet KAIJ in Dallas, Texas.
WTWW officially signed on at 1500 UTC on Friday, February 19, 2010 using the 9.48 MHz frequency at a low over-the-air power and streaming  with programming from the Scriptures for America broadcast network.As of March 2010, WTWW (as WBWW) is licensed to operate at 100 kilowatts with an azimuth of 40°, every day, on 5.755 MHz from 00:00 to 07:00 UTC and on 9.48 MHz from 12:00 to 19:00 and 22:00 to 24:00 UTC, targeting CIRAF zones 4 and 9 (eastern Canada), 18 and 27–28 (Europe), 37–38 (north Africa), 39 (the Middle East), and 46–47 (western and central Africa).WWCR
WWCR is a shortwave radio station located in Nashville, Tennessee in the United States. WWCR uses four 100 kW transmitters to broadcast on about a dozen frequencies.
WWCR mainly leases out its four transmitters to religious organizations and speakers, as well as serving as the shortwave home of Genesis Communications Network's programs. However, it does air a few hours of original programming per week.
F.W. Robbert Broadcasting also owns the AM (mediumwave) stations WNQM in Nashville, WMQM and WLRM in Memphis, WITA in Knoxville, and WVOG in New Orleans. Some of WWCR's programming is also broadcast on these local stations.WWVH
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.
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.
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.WYFR
WYFR was a shortwave radio station located in Okeechobee, Florida, United States. The station was owned by Family Stations, Inc., as part of the Family Radio network, and used to broadcast traditional Christian radio programming to international audiences. WYFR ceased all shortwave transmissions July 1, 2013. In December 2013, another shortwave broadcaster, WRMI of Miami, purchased the WYFR transmmission complex.World Harvest Radio International
World Harvest Radio International (WHRI) is a shortwave radio station in the United States, broadcasting conservative religious programming worldwide in the English language on a number of frequencies. Part of the LeSEA Christian broadcasting group, WHRI is based in Cypress Creek, South Carolina, with programs for audiences in Asia broadcast from T8WH in Palau.
Radio spectrum (ITU)