Longwave
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, medium-wave, and short-wave radio bands. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short'.
In contemporary usage, the term longwave is not defined precisely, and its intended meaning varies. It may be used for radio wavelengths longer than 1,000 m i.e. frequencies up to 300 kilohertz, including the International Telecommunication Union's low frequency and very low frequency bands. Sometimes the upper limit is taken to be higher than 300 kHz, but not above the start of the medium wave broadcast band at 520 kHz.
In Europe, Africa, and large parts of Asia, where a range of frequencies between 148.5 and 283.5 kHz is used for AM broadcasting in addition to the medium-wave band, the term longwave usually refers specifically to this broadcasting band, which falls wholly within the low frequency band of the radio spectrum. The "Longwave Club of America" is interested in "frequencies below the AM broadcast band".
Propagation
Because of their long wavelength, radio waves in this frequency range can diffract over obstacles like mountain ranges and travel beyond the horizon, following the contour of the Earth. This mode of propagation, called ground wave, is the main mode in the longwave band. The attenuation of signal strength with distance by absorption in the ground is lower than at higher frequencies, and falls with frequency. Low frequency ground waves can be received up to from the transmitting antenna. Very low frequency waves below 30 kHz can be used to communicate at transcontinental distances, and can penetrate saltwater to depths of hundreds of feet, and is used by the military to communicate with submerged submarines.Low frequency waves can also occasionally travel long distances by reflecting from the ionosphere, although this method, called skywave or "skip" propagation, is not as common as at higher frequencies. Reflection occurs at the ionospheric E layer or F layers. Skywave signals can be detected at distances exceeding from the transmitting antenna.
Non-broadcast use
Non-directional beacons
s transmit continuously for the benefit of radio direction finders in marine and aeronautical navigation. They identify themselves by a callsign in Morse code. They can occupy any frequency in the range 190–1750 kHz. In North America, they occupy 190–535 kHz. In ITU Region 1 the lower limit is 280 kHz.Time signals
There are institutional broadcast stations in the range that transmit coded time signals to radio clocks. For example:- WWVB in Colorado, United States, on 60 kHz
- DCF77 in Frankfurt, Germany, on 77.5 kHz
- JJY in Japan, on 40 & 60 kHz
- 66.66 kHz in Taldom transmitter, Russia
- BPC in Lintong, China, 68.5 kHz
- MSF time and 60 kHz frequency standard transmitted from Anthorn in the UK.
- TDF from Allouis, France, on 162 kHz
Longwaves travel by groundwaves that hug the surface of the earth, unlike mediumwaves and shortwaves. Those higher-frequency signals do not follow the surface of the Earth beyond a few kilometers, but can travel as skywaves, ‘bouncing’ off different layers of the ionosphere at different times of day. These different propagation paths can make the time lag different for every signal received. The delay between when the long-wave signal was sent from the transmitter and when the signal is received by the clock depends on the overland distance between the clock and the transmitter and the speed of light through the air, which is also very nearly constant. Since the time lag is essentially the same, a single constant shift forward from the time coded in the signal can compensate for all long-wave signals received at any one location from the same time signal station.
Submarine communication
The militaries of the United Kingdom, Russian Federation, United States, Germany, India and Sweden use frequencies below 50 kHz to communicate with submerged submarines.LowFER
In North America during the 1970s, the frequencies 167, 179 and 191 kHz were assigned to the short-lived Public Emergency Radio of the United States. Nowadays, in the United States, Part 15 of FCC regulations allows unlicensed use of 136 kHz and the 160–190 kHz band at output power up to 1 watt with up to a 15-meter antenna. This is called Low Frequency Experimental Radio. The 190–435 kHz band is used for navigational beacons.Historic
Swedish station SAQ, located at the Varberg Radio Station facility in Grimeton, is the last remaining operational Alexanderson alternator long-wave transmitter. Although the station ended regular service in 1996, it has been maintained as a World Heritage Site, and makes at least two demonstration transmissions yearly, on 17.2 kHz.Broadcasting
Longwave is used for broadcasting only within ITU Region 1. The long-wave broadcasters are located in western, northern, central, and southeastern Europe, the former Soviet Union, Mongolia, Algeria, and Morocco.Typically, a larger geographic area can be covered by a long-wave broadcast transmitter compared to a medium-wave one. This is because ground-wave propagation suffers less attenuation due to limited ground conductivity at lower frequencies.
Carrier frequencies
Long-wave carrier frequencies are exact multiples of 9 kHz; ranging from 153 to 279 kHz, except for a French-language station, Europe No. 1 in Germany. This station kept correctly spaced channels spacing for 4 months—only 7 years ago, and all Mongolian transmitters are 2 kHz above the internationally recognized channels.Until the 1970s, some long-wave stations in northern and eastern Europe and the Soviet Union operated on frequencies as high as 433 kHz.
Some radio broadcasters, for instance Droitwich transmitting station in the UK, derive their carrier frequencies from an atomic clock, allowing their use as frequency standards. Droitwich also broadcasts a low bit-rate data channel, using narrow-shift phase-shift keying of the carrier, for Radio Teleswitch Services.
In 2014 and 2015 Russia closed all of its LW broadcast transmitters.
Long-distance reception
Because long-wave signals can travel very long distances, some radio amateurs and shortwave listeners engage in an activity called DXing. DXers attempt to listen in to far away transmissions, and they will often send a reception report to the sending station to let them know where they were heard. After receiving a report, the sending station may mail the listener a QSL card to acknowledge this reception.Reception of long-wave signals at distances in excess of have been verified.
List of long-wave broadcasting transmitters
List of stations currently operating
Freq. | Station name | Language | Country | Location | Aerial type | Power | Coordinates | Notes |
153 | Radio Antena Satelor | Romanian | Brașov | T-aerial on 2 guyed steel lattice masts, height: | 200 | Fifth state-owned radio station in Romania | ||
162 | ANFR | French | Allouis | Two guyed lattice steel masts, height: fed on the top | 1000 / 2000 | Time signal phase-modulated; the frequency broadcast France Inter until the end of 2016. Now only the time signal for public clocks is transmitted. The ANFR is in charge of this. | ||
164 | MNB Radio 1 | Mongolian | Ulaanbaatar | tall cable-stayed steel truss mast | 500 | Broadcasts from 21:00 to 14:00 UTC | ||
171 | Médi 1 | Arabic and French | Nador | Directional aerial consisting of three guyed steel lattice masts, tall | 1600 | Private and commercial Moroccan radio network | ||
189 | RÚV Rás 1/RÚV Rás 2 | Icelandic | Gufuskalar near Hellissandur | Slight oval bi-directivity aerial, top loaded parallel connected triangular loops, mast as a common member, all guys insulated except two radiating diametrically opposed grounded top guys, loops closed by copper straps in the ground from two conducting guy grounding points to base of the guyed steel lattice mast insulated against ground, height: | 300 | Iceland's national public service broadcaster | ||
198 | BBC Radio 4/BBC World Service | English | Droitwich | T-aerial on two guyed steel lattice masts insulated against ground with a height of | 500 | All four transmitters carry Radio teleswitch PSK data; Droitwich relays BBC World Service from 01:00 to 05:20 UTC | ||
198 | BBC Radio 4/BBC World Service | English | Burghead | Omnidirectional aerial, guyed steel lattice mast, height | 50 | All four transmitters carry Radio teleswitch PSK data; Droitwich relays BBC World Service from 01:00 to 05:20 UTC | ||
198 | BBC Radio 4/BBC World Service | English | Westerglen | Omnidirectional aerial, guyed steel lattice mast, height | 50 | All four transmitters carry Radio teleswitch PSK data; Droitwich relays BBC World Service from 01:00 to 05:20 UTC | ||
198 | BBC Radio 4/BBC World Service | English | Dartford Tunnel | 0.004 | - | All four transmitters carry Radio teleswitch PSK data; Droitwich relays BBC World Service from 01:00 to 05:20 UTC | ||
207 | RÚV Rás 1/RÚV Rás 2 | Icelandic | Eiðar near Egilsstaðir | Omnidirectional aerial, steel lattice mast insulated against ground, height | 100 | Iceland's national public service broadcaster | ||
209 | MNB Radio 1 | Mongolian | Choibalsan | Cable-stayed steel truss mast, height: | 75 | Broadcasts from 21:00 to 14:00 UTC | ||
209 | MNB Radio 1 | Mongolian | Dalanzadgad | Cable-stayed steel truss mast, height: | 75 | Broadcasts from 21:00 to 14:00 UTC | ||
209 | MNB Radio 1 | Mongolian | Olgii | Omnidirectional antenna, high guyed mast | 30 | Broadcasts from 21:00 to 14:00 UTC | ||
225 | Polish Radio Programme One | Polish | Solec Kujawski | Directional aerial, two guyed radio masts fed on the top, heights and | 1000 | Earlier Konstantynów was used | ||
227 | MNB Radio 1 | Mongolian | Altai | Cable-stayed steel truss mast | 75 | Broadcasts from 21:00 to 14:00 UTC | ||
234 | RTL | French | Beidweiler | Directional aerial, three guyed grounded steel lattice masts, high, with vertical cage aerials | 1500 / 2000 | Spare transmitter site Junglinster | ||
243 | DR Langbølge | Danish | Kalundborg | Semi-directional Alexanderson antenna 153/333 degrees, two grounded steel lattice radiating towers with interconnecting top wire capacitance | 50 | Transmitting in time slots only | ||
252 | Radio Algeria Chaîne 3 | Arabic | Tipaza | Omnidirectional aerial, single guyed lattice steel mast, height | 750 / 1500 | Half transmitter power during night | ||
252 | RTÉ Radio 1 | English and Irish | Clarkstown | Omnidirectional aerial, guyed steel lattice mast, insulated against ground, height | 150 / 300 | The only AM transmitter for RTÉ Radio 1, power is decreased at night to 100 kW, it was scheduled to cease broadcasting in June 2019 In April 2019 it announced an antenna upgrade and the closure was postponed. | ||
270 | ČRo Radiožurnál | Czech | Topolná | Directional aerial, two grounded high guyed steel lattice mast with cage aerials | 50 | Broadcasting from Monday to Friday 05:00–24:00 CET and 06:00–24:00 CET at weekends |
List of stations that have closed or are otherwise inactive
Freq. | Station name | Country | Location | Aerial type | Power | Coordinates | Notes |
153 | - | - | - | - | - | - | - |
153 | Deutschlandfunk | Donebach | Directional aerial, two guyed steel lattice masts, 363 m high, fed at the top | 500 | ; | closed | |
153 | Radio Mayak | Ashgabat | 650 | closed | |||
153 | YuFM | Taldom transmitter | Omnidirectional aerial, guyed steel lattice mast of 257 m height | 300 | closed | ||
153 | NRK P1/P2 | Ingøy | Omnidirectional aerial, guyed steel lattice mast tall, fed at the top, ex-Omega equipment | 100 | closed | ||
153 | Radio Rossii | Popova near Komsomolsk-na-Amure | 1200 | closed | |||
153 | Radio Algerie Chaîne 1 | Kénadsa | Three tall guyed masts | 500 | inactive | ||
162 | TRT Radyo 4 | Agri | Two guyed lattice steel masts, height 250 m | 1000 | ; | inactive | |
162 | Kanal Uzbekistan | Tashkent | 150 | closed | |||
162 | Radio Rossii | Norilsk | Omnidirectional antenna, 205 m high antenna | 150 | ? | closed | |
162 | Radio Yuldash, Radio Rossii | Ufa | 150 | closed | |||
171 | - | - | - | - | - | - | - |
171 | NPO Radio 1 | Lopik | 500 | closed | |||
171 | Radio-1 | Lapichi | ? | 500/1000 | closed | ||
171 | Voice of Russia | Oktyabrsky | 257 m metres tall antenna. | 1200 | closed | ||
171 | Radio Rossii | Bolshakovo near Kaliningrad | Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna | 600 | closed | ||
171 | Radio Ukraine 1 | Krasne near Lviv | Omnidirectional antenna, 259 m high guyed lattice steel mast with cage antenna | 150/75 | inactive | ||
171 | Radio Rossii | Raduga | Omnidirectional antenna, 255 m high guyed lattice steel mast with cage antenna | 250 | closed | ||
171 | Radio 1 | Murmansk | Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna | 150 | closed | ||
171 | Radio 1 | Noginsk | Omnidirectional antenna, 242 m high guyed lattice steel mast with cage antenna | 150 | closed | ||
171 | Radio 1 | Ezhva near Syktyvkar | Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna | 150 | closed | ||
171 | Radio Rossii | Tulagino near Yakutsk | Omnidirectional antenna, circle antenna with 1 central and 6 ring masts | 150 | ; ; ; ; ; ; | closed | |
177 | - | - | - | - | - | - | - |
177 | Deutschlandradio Kultur | Zehlendorf near Oranienburg | Omnidirectional aerial, cage aerial mounted on 359.7 m high guyed mast, triangle aerial on 3 150 m high guyed steel lattice masts | 500 | closed | ||
180 | TRT Radyo 1 | Polatli | Omnidirectional antenna, 250 m high guyed latice steel mast | 1200 | inactive | ||
180 | Radio Rossii | Yelizovo near Petropavlovsk-Kamchatskiy | Omnidirectional antenna, 255 m high guyed lattice steel mast | 150 | closed | ||
180 | Radio Mayak | Kruchina near Chita | Omnidirectional antenna, 200 m high guyed lattice steel mast | 150 | inactive | ||
180 | Kazakh Radio 1 | Alma-Ata | 250 | closed | |||
180 | Kazakh Radio 1 | Aktyubinsk | 150 | closed | |||
180 | Kazakh Radio 1 | Chimkent | 50 | closed | |||
183 | - | - | - | - | - | - | - |
183 | Europe 1 | Felsberg-Berus | Directional aerial, four ground insulated steel lattice masts,, and tall; spare aerial: two ground insulated steel lattice masts, height: | 750 | Main antenna: Spare antenna: | closed | |
189 | - | - | - | - | - | - | - |
189 | Rai Radio 1 | Caltanissetta | Omnidirectional aerial, guyed steel lattice mast, height 282 m | 10 | closed | ||
189 | Sveriges Radio P1 | Orlunda, near Motala | 300 | closed | |||
189 | Radio Rossii | Kostantinogradovka near Blagoveshchensk | Omnidirectional aerial, 257 m high guyed lattice steel mast with cage antenna | 1200 | closed | ||
189 | Sakartvelos Radio | Dusheti | 250 | inactive | |||
198 | - | - | - | - | - | - | - |
198 | Polskie Radio Parlament/Radio Polonia | Raszyn | Omnidirectional aerial, guyed steel lattice mast insulated against ground, 335 m high | 200 | closed | ||
198 | Chaine 1 | Berkaoui | 2000 | closed | |||
198 | Radio Mayak | Saint Petersburg – Olgino | Omnidirectional aerial, 205 m high guyed steel lattice mast | 150 | inactive | ||
198 | Radio Mayak | Angarsk | Before 2001: T-antenna spun between 2 205 m tall guyed steel lattice mast | 250 | , possibly | closed | |
198 | Radio Mayak | Avsyunino | Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna | 150 | inactive | ||
198 | Radio Mayak | Ufa | 150 | closed | |||
198 | Radio 1 | Krasnaya Rechka near Bishkek | 150 | closed | |||
207 | - | - | - | - | - | - | - |
207 | RNE Radio 5 | Logroño | Directional antenna, 300 metres tall. | >100 | closed | ||
207 | Radio Ukraine 1 | Brovary | Omnidirectional antenna, 259.6 m high guyed lattice steel mast with cage antenna | 600 | closed | ||
207 | Radio al-Urdunniya | Al Karanah | ? | ; | closed | ||
207 | Radio Mayak | Tynda | Omnidirectional aerial, steel lattice mast insulated against ground, height 244 m | 150 | closed | ||
207 | Deutschlandfunk | Aholming | Directional aerial, two guyed steel lattice masts, 265 m high, fed at the top | 500 | ; | closed | |
207 | SNRT Al Idaâ Al-Watania | Azilal Demnate | tall guyed mast | 400 | inactive | ||
209 | - | - | - | - | - | - | - |
209 | Radio Mayak | Tynda | 150 | closed | |||
216 | - | - | - | - | - | - | - |
216 | NRK P1 | Lambertseter near Oslo | 200 | closed | |||
216 | Radio Monte Carlo Info | Roumoules | Directional aerial, three high guyed steel lattice masts, high guyed steel lattice mast as backup aerial | 700 / 1400 | , Backup antenna: | closed | |
216 | Azerbaijan Radio | Baku | 500 | closed | |||
216 | Radio Rossii | Krasnoyarsk | Omnidirectional antenna, guyed lattice steel mast, 210 m tall | 150 | closed | ||
216 | Radio Rossii | Atamanovka | Directional antenna | 150 | closed | ||
216 | Radio Rossii | Birobidzhan | 2 guyed masts, 260 m high | 30 | ; | closed | |
225 | TRT GAP | Van | Omnidirectional antenna, 250 m high guyed lattice steel mast | 600 | inactive | ||
225 | Radio Rossii | Surgut | Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna | 1000 | closed | ||
234 | - | - | - | - | - | - | - |
234 | Radio Moldova | Grigoriopol | 1000 | closed | |||
234 | Radio Jamahiriya | Yafran near Tripoli | 1000 | closed | |||
234 | Radio 1 | Krasny Bor transmitter near Sankt-Peterburg | Omnidirectional aerial, 271.5 metres tall guyed mast with cage antenna | 1200 | closed | ||
234 | Public Armenian Radio | Kamo | ? | 500 | ? | closed | |
234 | Radio Rossii | Koskovo near Murmansk | Omnidirectional aerial, 210 m tall guyed mast | 250 | inactive | ||
234 | Radio 1 | Novosemeykino near Samara | Four 205 metres tall towers insulated against ground arranged in a square | 2000 | ; ; ; | closed | |
234 | Radio Rossii | Raduzhnyy near Magadan | Omnidirectional aerial, 259 m high guyed lattice steel mast with cage antenna | 1000 | closed | ||
234 | Radio Rossii | Odinsk near Irkutsk | Omnidirectional aerial, 259 m high guyed lattice steel mast with cage antenna | 500 | closed | ||
234 | Radio 1 | Koskovo near Arkhangelsk | Omnidirectional aerial, 257 m high guyed lattice steel mast with cage antenna | 500 | closed | ||
243 | TRT Radyo 4 | Erzurum | Omnidirectional antenna, 185 m high guyed lattice steel mast | 200 | inactive | ||
243 | Radio Rossii | Razdolnoye near Ussuriysk | Omnidirectional antenna, 259 m high guyed lattice steel mast with cage antenna | 1000 | closed | ||
243 | Kazakh Radio 2 Shalkar | Karaganda | Omnidirectional aerial, guyed steel lattice mast of 254 m height | 1000 | closed | ||
243 | Kazakh Radio 2 Shalkar | Alma-Ata | 1000 | closed | |||
252 | - | - | - | - | - | - | - |
252 | Armenian Radio 1 | Kamo | 150 | ? | closed | ||
252 | Yle Radio 1 | Lahti | 200 | , | closed | ||
252 | Radio Tojikston | Dushanbe | 150 | closed | |||
252 | Radio Rossii | Kazan | Omnidirectional aerial, 152 m high guyed lattice steel mast with cage antenna | 100 | closed | ||
261 | - | - | - | - | - | - | - |
261 | Radioropa Info | Burg | Omnidirectional aerial, cage aerial on 324 m high guyed, grounded steel lattice mast, 210 m high steel tube mast, insulated against ground | 200 | closed | ||
261 | Radio Rossii | Taldom | Omnidirectional antenna, circle antenna with 1 central and 5 ring masts, height of central mast 275 m | 2500 | ; ; ; ; ; | closed | |
261 | Radio Rossii | Kruchina near Chita | Omnidirectional antenna, guyed lattice steel mast, 260 m high | 150 | closed | ||
261 | Radio Rossii | Tyumen | Omnidirectional antenna, guyed lattice steel mast, 220 m high | 150 | closed | ||
261 | Radio Rossii | Vorkuta | Omnidirectional antenna, guyed lattice steel mast, 220 m high | 50 | closed | ||
261 | Radio Horizont | Vakarel | One of the few Blaw-Knox Towers in Europe, 215 m high | 75 | closed | ||
270 | - | - | - | - | - | - | - |
270 | Radio Rossii | Orenburg | Omnidirectional aerial, guyed steel lattice mast of 137 m height | 25 | closed | ||
270 | Radio 1 | Khabarovsk | 2 guyed steel lattice masts, height: 164 m | 150 | ; | closed | |
270 | Radio Slovo | Novosibirsk | ? | 150 | ? | closed | |
279 | - | - | - | - | - | - | - |
279 | Radio Rossii | Gorno-Altaisk | Omnidirectional antenna, 143m high guyed lattice steel mast | 50 | closed | ||
279 | Radio Rossii | Selenginsk | Omnidirectional aerial, 260 m high guyed lattice steel mast with cage antenna | 150 | closed | ||
279 | Radio Rossii | Vestochka near Yuzhno-Sakhalinsk | Omnidirectional antenna, guyed lattice steel mast, 258 m high | 1000 | closed | ||
279 | Radio Rossii | Yekaterinburg | Omnidirectional aerial, guyed steel lattice mast of 256 m height, fed at the top | 150 | closed | ||
279 | BR Pershy Kanal/BR Radyjo Stalitsa | Sasnovy | 353.5 metres tall guyed mast | 500 | closed | ||
279 | TR1 Watan Radio | Ashgabat | Cable-stayed steel truss mast | 150 | inactive | ||
279 | MusicMann 279 | Isle of Man | Crossed field | never launched |