Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz ; above the medium frequency band (MF), to the bottom of the VHF band.
International broadcasting, in a limited extent, began during World War I, when German and British stations broadcast press communiqués using Morse code. With the severing of Germany's undersea cables, the wireless telegraph station in Nauen was the country's sole means of long-distance communication.
Medium wave (MW) is the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. During the daytime, reception is usually limited to more local stations, though this is dependent on the signal conditions and quality of radio receiver used. Improved signal propagation at night allows the reception of much longer distance signals. This can cause increased interference because on most channels multiple transmitters operate simultaneously worldwide. In addition, amplitude modulation (AM) is often more prone to interference by various electronic devices, especially power supplies and computers. Strong transmitters cover larger areas than on the FM broadcast band but require more energy and longer antennas. Digital modes are possible but have not reached momentum yet.
Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers. Frequencies immediately below MF are denoted as low frequency (LF), while the first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM radio broadcasting, navigational radio beacons, maritime ship-to-shore communication, and transoceanic air traffic control.
In radio, longwave, long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with wavelengths longer than what was originally called the medium-wave broadcasting band. The term is historic, dating from the early 20th century, when the radio spectrum was considered to consist of longwave (LW), medium-wave (MW), and short-wave (SW) radio bands. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short'.
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. CHU's signal is used for continuous dissemination of official Canadian government time signals, derived from atomic clocks.
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.
JJY is the call sign of a low frequency time signal radio station located in Japan.
Grimeton Radio Station in southern Sweden, close to Varberg in Halland, is an early longwave transatlantic wireless telegraphy station built in 1922–1924, that has been preserved as a historical site. From the 1920s through the 1940s it was used to transmit telegram traffic by Morse code to North America and other countries, and during World War II was Sweden's only telecommunication link with the rest of the world. It is the only remaining example of an early pre-electronic radio transmitter technology called an Alexanderson alternator. It was added to the UNESCO World Heritage List in 2004, with the statement: "Grimeton Radio Station, Varberg is an outstanding monument representing the process of development of communication technology in the period following the First World War." The radio station is also an anchor site for the European Route of Industrial Heritage. The transmitter is still in operational condition, and each year on a day called Alexanderson Day is started up and transmits brief Morse code test transmissions, which can be received all over Europe.
HCJB, "The Voice of the Andes", was the first radio station with daily programming in Ecuador and the first Christian missionary radio station in the world. The station was founded in 1931 by Clarence W. Jones, Reuben Larson, and D. Stuart Clark. HCJB now focuses on Ecuador with unified programming on FM at 89.3 MHz in Pichincha, at 92.5 MHz in Manabí, at 96.1 MHz in Tungurahua and Cotopaxi, at 98.3 MHz in Esmeraldas and with separate programming on AM at 690 kHz. Broadcasts in Spanish and indigenous languages on 6.05 MHz (1 kW), continue on an intermittent basis with a new solid state transmitter which in 2017 replaced an older (5 kW) transmitter. These broadcasts were not listed on the HCJB English website as of February 2016.
WRMI is a shortwave radio station broadcasting from Okeechobee, Florida, United States. WRMI is a commercial radio station that sells airtime to businesses and organizations.
Voice of Korea is the international broadcasting service of North Korea. It broadcasts primarily information in Chinese, Spanish, German, English, French, Russian, Japanese and Arabic. Until 2002 it was known as Radio Pyongyang. The interval signal is identical to that of Korean Central Television.
WRNO 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.
Kossuth Rádió is a public-broadcasting radio station in Hungary, concentrating on news and current affairs. It is one of the seven national radio channels produced by MTVA. It was established in 1925 as Radio Budapest and named after Lajos Kossuth, a Hungarian national hero, in 1949.
Radio Romania International is a Romanian radio station owned by the Romanian public radio broadcaster Societatea Română de Radiodifuziune that broadcasts abroad. It was created in 1927 and was known as Radio Bucharest before 1989.
KMJ is a commercial AM radio station in Fresno, California. It airs a Republican news/talk radio format, and simulcasts with sister station KMJ-FM. Owned by Cumulus Media, the studios and offices are located at the Radio City building on Shaw Avenue in North Fresno.
Nauen Transmitter Station in Nauen, Havelland district, Brandenburg, Germany, is the oldest continuously operating radio transmitting installation in the world. Germany's first high power radio transmitter, it was founded on 1 April 1906 by Telefunken corporation and operated as a longwave radiotelegraphy station through World War II, and during World War I became Germany's main link with the outside world when its submarine communications cables were cut. Upgraded with shortwave transmitters in the 1920s it was Germany's most advanced long range radio station, continually upgraded with the latest equipment and serving as an experimental station for Telefunken to test new technology. At the end of World War II, invading Russian troops dismantled and removed the transmitting equipment. During the Cold War it served as the GDR's international shortwave station Radio Berlin International (RBI), and was the East Bloc's second most powerful radio station, disseminating Communist propaganda to other countries. Since German Reunification in 1991 it has been operated by Deutsche Telekom, Germany's state telecommunication service. The original 1920 transmitter building designed by architect Herman Muthesius is still used; it is the only remaining building designed by that architect.
The Grigoriopol transmitter, officially the Transnistrian Radio and Television Center, is a very large broadcasting facility situated near Maiac, an urban settlement 11 km northeast of Grigoriopol, Transnistria (Moldova).
WMLK (9.275 MHz) is a shortwave radio station in Bethel, Pennsylvania owned by the Assemblies of Yahweh. WMLK derives its callsign from MLK, representing the consonants of the Hebrew word "malak" meaning a "messenger" or angel. A different vocalisation of the word will also yield the definition salt.
