Rugby VLF transmitter
Encyclopedia
Hillmorton
Hillmorton is an area of the town of Rugby, Warwickshire, it comprises most of the eastern half of the town.Hillmorton was historically a village in its own right, and was mentioned in the Domesday Book as land that belonged to Hugh de Grandmesnil, at one time a market was held in Hillmorton, and...
near the town of Rugby
Rugby, Warwickshire
Rugby is a market town in Warwickshire, England, located on the River Avon. The town has a population of 61,988 making it the second largest town in the county...
, Warwickshire
Warwickshire
Warwickshire is a landlocked non-metropolitan county in the West Midlands region of England. The county town is Warwick, although the largest town is Nuneaton. The county is famous for being the birthplace of William Shakespeare...
in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, situated just west of the A5 trunk road and in later years junction 18 of the M1 motorway. Its large very low frequency
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...
(VLF) transmitter came into service on 1 January 1926 and was originally used to transmit telegraph messages to the Commonwealth
Commonwealth of Nations
The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...
as part of the Imperial Wireless Chain
Imperial Wireless Chain
The Imperial Wireless Chain, also known as the Empire Wireless Chain, was a strategic international wireless telegraphy communications network, created to link the countries of the British Empire. Although the idea was conceived prior to World War I, Britain was the last of the world's Great Powers...
. After the 1950s this transmitter, active as callsign GBR on 16.0 kHz,using Morse Code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
and latter on 15.975 kHz with Frequency-shift keying
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
FSK and Minimum-shift keying
Minimum-shift keying
In digital modulation, minimum-shift keying is a type of continuous-phase frequency-shift keying that was developed in the late 1950s and 1960s. Similar to OQPSK, MSK is encoded with bits alternating between quadrature components, with the Q component delayed by half the symbol period. However,...
MSK, was used for transmitting messages to submerged 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. Criggion radio station acted as a reserve. The GBR transmitter was shut down on 1 April 2003 and was replaced by a new one at the Skelton transmitting station.
In 1927, a second transmitter was installed to initiate the first transatlantic commercial telephone service;linking New York and London on 60 kHz using single-sideband modulation
Single-sideband modulation
Single-sideband modulation or Single-sideband suppressed-carrier is a refinement of amplitude modulation that more efficiently uses electrical power and bandwidth....
. This transmitter was decommissioned in 1956 and became the time signal transmitter MSF. This new function developed from the decision, in 1951, to use the station to transmit modulated standard frequencies
Frequency standard
A frequency standard is a stable oscillator used for frequency calibration or reference. A frequency standard generates a fundamental frequency with a high degree of accuracy and precision. Harmonics of this fundamental frequency are used to provide reference points.Since time is the reciprocal of...
for scientific reference purposes. In 1972 these transmissions were consolidated onto the present frequency of 60 kHz and a further reference, that of a time signal, was added. In 1977 this took the form of the rolling slow code in use until April 2007, when BT's contract to transmit the time signal also passed to VT Communications, using their Anthorn radio station in Cumbria.
The aerial system at the VLF transmitter existed between 1926 and 2004 and consisted of twelve 250 metre (820 ft) high, guyed steel-framework masts insulated against ground and carrying an aerial wire. This wire was mainly destroyed by heavy iceloads in the winter of 1940. From the shutdown of GBR, the facility was only used for transmitting the MSF time signal. Therefore, 8 of the 12 masts were obsolete and demolished on the night of 19 June 2004 to 20 June 2004.
The remaining four 'tall' masts were demolished on the afternoon (around 1500 hrs local time) of August 2, 2007 – with no prior publicity of this end of an era.
A trial transmission of the LORAN-C navigation system was run at the station from June 2005 until March 2007.
See also
- List of masts
- List of tallest buildings and structures in Great Britain
- List of radio stations in the United Kingdom
External links
- A History of Rugby Radio
- The Official History of Rugby Radio Station
- National Physical Laboratory – news of the MSF Move
- Pictures of the Station
Schematics of the masts
- http://www.skyscraperpage.com/diagrams/?b45614
- http://www.skyscraperpage.com/diagrams/?b45615
- http://www.skyscraperpage.com/diagrams/?b45616
- http://www.skyscraperpage.com/diagrams/?b45617
The four remaining VLF towers are demolished (02/08/07)
- http://www.youtube.com/watch?v=bx2lhSUuGqU