Orfordness transmitting station
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The Orfordness transmitting station is a medium-wave broadcasting facility owned by VT Communications at Orford Ness, UK (grid reference TM450511). Its facilities are leased to international broadcasters, especially the BBC World Service.
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[edit] History
The site was originally built for an experimental over-the-horizon radar station known as Cobra Mist.
The radar never worked satisfactorily and the project was scrapped. The site and buildings were then taken over by the Foreign and Commonwealth Office's Diplomatic Wireless Service, who installed a medium-wave broadcast transmitter there. This was leased to the BBC. Later, the BBC itself owned the site. Later still, after the BBC's transmission facilities were privatised, the site belonged to Merlin Communications. In 2001 this company was taken over by VT Group plc (known as Vosper Thorneycroft until 2002) and renamed VT Merlin Communications, then just VT Communications.
[edit] Broadcasts
Orfordness broadcasts the BBC World Service continuously on 648 kHz AM and also at certain times of the day on 1296 kHz DRM. The AM broadcasts are among a small number which are augmented with the AM Signalling System to provide a station label and alternative frequency information similar to that provided on FM with RDS.
[edit] Transmitters
There are a number of transmitters on site, the newest of which is a 200 kW NA200 from Nautel of Canada.
The NA200 was commissioned in 2003 prior to the World Radiocommunications Conference (WRC) in Geneva, Switzerland, and was on-the-air with a Digital Radio Mondiale signal for the inaugural DRM broadcasts.
[edit] Aerial systems
The station has two directional aerial systems: one for 648 kHz and one for 1296 kHz.
The directional aerial for 648 kHz consists of a row of five freestanding steel lattice towers of triangular cross section, insulated at their base. All five towers are driven.
The directional aerial for 1296 kHz consists of six freestanding steel lattice towers. Unlike the directional aerial for 648 kHz, they are arranged in two parallel rows with three towers in each. Only the middle tower of each three is driven: the other towers act as passive reflector and director elements.
There is also a back-up omni-directional antenna for 648 kHz.
[edit] See also
[edit] External links
- Orfordness Nature Reserve — National Trust
- http://tx.mb21.co.uk/gallery/orfordness.php
- Radio Nationaal — Medium Wave broadcasting to Holland from Orfordness, Suffolk
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