Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it 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 a 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.
Very low frequency or VLF is the ITU designation for radio frequencies (RF) in the range of 3–30 kHz, corresponding to wavelengths from 100 to 10 km, respectively. The band is also known as the myriameter band or myriameter wave as the wavelengths range from one to ten myriameters. Due to its limited bandwidth, audio (voice) transmission is highly impractical in this band, and therefore only low data rate coded signals are used. The VLF band is used for a few radio navigation services, government time radio stations and for secure military communication. Since VLF waves can penetrate at least 40 meters (131 ft) into saltwater, they are used for military communication with submarines.
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.
JJY is the call sign of a low frequency time signal radio station located in Japan.
All India Radio (AIR), also known as Akashvani or Akashbani, is an Indian state-owned public radio broadcaster founded by the Government of India, owned by the Ministry of Information and Broadcasting and one of Prasar Bharati's two divisions. It was established in 1936. It is the sister service of Prasar Bharati's Doordarshan, an Indian television broadcaster. Headquartered in the Akashvani Bhavan building in New Delhi, it houses the Drama Section, the FM Section, and the National Service, and is also home to the Indian television station Doordarshan Kendra, (Delhi).
The Voice of Greece, also known as ERA 5, is the international service of Greek state radio on shortwave and via satellite and the internet. On 11 June 2013, the Greek government announced the closure of the state broadcaster ERT from 12 June 2013 as an austerity measure.
Vatican Radio is the official broadcasting service of Vatican City.
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.
MW DX, short for mediumwave DXing, is the hobby of receiving distant mediumwave radio stations. MW DX is similar to TV and FM DX in that broadcast band (BCB) stations are the reception targets. However, the nature of the lower frequencies used by mediumwave radio stations is very much different from that of the VHF and UHF bands used by FM and TV broadcast stations, and therefore involves different receiving equipment, signal propagation, and reception techniques.
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.
ALS162 is a French longwave time signal and standard-frequency radio station and is used for the dissemination of the Metropolitan French national legal time to the public. TéléDiffusion de France broadcast the ALS162 time signal, provided by LNE-SYRTE and LNE-LTFB time laboratories under ANFR responsibility, from the Allouis longwave transmitter at 162 kHz, with a power of 800 kW.
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.
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 one of the many remaining buildings designed by that architect that is a protected cultural heritage site.
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).
