Grimeton VLF transmitter
Encyclopedia
Very low frequency
225px|thumb|right|A VLF receiving antenna at [[Palmer Station]], Antarctica, operated by Stanford UniversityVery low frequency or VLF refers to radio frequencies in the range of 3 kHz to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals...
transmission facility at Grimeton close to Varberg
Varberg Municipality
Varberg Municipality is a municipality in Halland County, in southwest Sweden. Its seat is in Varberg.It was formed in 1971 through the amalgamation of the City of Varberg and the surrounding rural municipalities...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
. It has the only workable machine transmitter
Alexanderson alternator
An Alexanderson alternator is a rotating machine invented by Ernst Alexanderson in 1904 for the generation of high frequency alternating current up to 100 kHz, for use as a radio transmitter...
in the world and is classified as World Heritage Site.
The transmitter was built in 1922 to 1924; to operate at 17.2 kHz, although it is designed for frequencies around 40 kHz. The radiating element is a wire aerial hung on six 127-metre high freestanding steel pylons
Lattice tower
A lattice tower or truss tower is a freestanding framework tower. They can be used as electricity pylons especially for voltages above 100 kilovolts, as a radio tower or as an observation tower....
, that are grounded.
The Grimeton VLF transmitter location is also used for shortwave transmissions, FM
FM broadcasting
FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
and TV broadcasting. For this purpose, a 260 metre high guyed steel framework mast
Guyed mast
A guyed mast is a tall thin vertical structure that receives support from guy lines.Guyed masts are frequently used for radio masts. The mast can either support aerials mounted at its top, or the entire structure itself can function as an antenna ; this is called a mast radiator...
was built in 1966 next to the building containing the 40 kHz transmitter.
In 1945 the Grimeton VLF transmitter's twin station Nadawcza Radiostacja Transatlantycka Babice in Babice
Boernerowo
Boernerowo is a neighbourhood in the Warsaw's borough of Bemowo. Initially the spot was occupied by a small village called Babice, with an eponymous fort located in its centre. In early 1920s the area surrounding the fort was bought by the Polish state and in 1922 the Ministry of Post and...
, Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
was destroyed. Until the 1950s, the Grimeton VLF transmitter was used for transatlantic radio telegraphy to Radio Central in Long Island, New York
Long Island
Long Island is an island located in the southeast part of the U.S. state of New York, just east of Manhattan. Stretching northeast into the Atlantic Ocean, Long Island contains four counties, two of which are boroughs of New York City , and two of which are mainly suburban...
, USA. From the 1960s until 1996 it transmitted orders to submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
s in the Swedish Navy
Swedish Navy
The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...
.
In 1968 a second transmitter was installed which uses the same aerial as the machine transmitter but with transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
and tube technology. The machine transmitter become obsolete in 1996 and went out of service. However, because it was still in good condition it was declared a national monument and can be visited during the summer.
On July 2, 2004, the Grimeton VLF transmitter was declared a World Cultural Heritage
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
site by UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
. It continues to be used on special occasions such as Alexanderson Day
Alexanderson Day
Alexanderson Day, named after the Swedish radio engineer Ernst Fredrik Werner Alexanderson and held either on the last Sunday in June, or on the first Sunday in July, whichever comes closer to 2nd of July , is the day of the open house at the Swedish government VLF transmitter Grimeton, call sign...
to transmit Morse messages on 17.2 kHz. Its call sign
Call sign
In broadcasting and radio communications, a call sign is a unique designation for a transmitting station. In North America they are used as names for broadcasting stations...
is SAQ. The transmitter from the 1960s is still used by the Swedish Navy. Since it uses the same aerial as the machine transmitter, a simultaneous operation of both transmitters, which would require expensive frequency filters, is not possible. Therefore the special transmissions from that machine transmitter are very rare.
Recent transmissions from SAQ were made on Jul. 4, Oct. 24, and Dec. 24, 2010, and on Jan. 4, April 14 and July 3, 2011. The transmission from SAQ at 08:00 UTC on Christmas Eve (24 December) is repeated annually.
External links
- Official website
- World Heritage profile
- Grimeton VLF transmitter tower 1, ScyscraperPage
- Grimeton VLF transmitter tower 2, ScyscraperPage
- Grimeton VLF transmitter tower 3, ScyscraperPage
- Grimeton VLF transmitter tower 4, ScyscraperPage
- Grimeton VLF transmitter tower 5, ScyscraperPage
- Grimeton VLF transmitter tower 6, ScyscraperPage
- Grimeton TV mast, ScyscraperPage
- Alexanderson Society official webpage
- http://hamradio.pl/wiki/Nadawcza_Radiostacja_Transatlantycka_Babice
- http://pl.wikipedia.org/wiki/Transatlantycka_Centrala_Radiotelegraficzna