Orfordness transmitting station

The Orfordness transmitting station is a major (though now, little used) radio broadcasting facility at Orford Ness on the Suffolk coast in the UK. It is designed to transmit powerful medium-wave (AM) signals to much of Europe on two frequencies (648 and 1296 kHz). Built in the 1970s and early 1980s by the British government, it is now owned by a large engineering and defence services company, the Babcock International Group.

Over the years, the Orfordness station has carried a variety of radio services. It is best known, particularly in the UK, for transmitting the BBC World Service in English around the clock on 648 kHz from September 1982 until March 2011. Following the ending of these broadcasts, and with no other major clients for the station, its future is uncertain.

The station's name is written as one word while the shingle spit on which it sits is two words.

History

The former Cobra Mist building in October 2004

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 in 1973. The site and buildings were taken over in 1975 by the Foreign and Commonwealth Office's Communications Engineering Department (still better known by its previous name, the Diplomatic Wireless Service), who installed a 50-kW medium-wave broadcast transmitter.^[1] Following successful tests and the installation of further transmitters, from 1978 the site gradually took over responsibility for the BBC's medium-wave services to Europe which had been provided since the Second World War by an FCO transmitting station at Crowborough in Sussex. From September 1982, Orfordness handled all such BBC transmissions. In 1986, the BBC itself took over the running of the site from the FCO, although the latter retained ownership of the station.

In 1997, as part of the privatization of all transmitting stations in the UK used by the BBC, the station was bought by Merlin Communications International Ltd (usually known simply as Merlin), a company formed by former BBC engineers and frequency managers. In 2001, Merlin was acquired by VT Group plc (known as Vosper Thorneycroft until 2002) and renamed VT Merlin Communications, then just VT Communications. In 2010, VT Communications was bought by Babcock.

Use of the two frequencies

From September 1982, the 648 kHz channel was used to carry BBC World Service programmes in English around the clock. From 1987 and into the 1990s, the channel carried a tailored service, branded BBC 648, in which some French and German programmes were interwoven with the main output in English.^[2] "BBC 648" ended in 1999 with the closure of the BBC's German service, and 648 reverted to being English-only.^[3] (The French for Europe service had closed in 1995.^[4])

The 1296 kHz channel was used for BBC broadcasts in east European languages during the evening and early morning. This use of 1296 was phased out once the BBC was able to be relayed on FM within the target countries, following the end of the Cold War. In 2001, the Dutch station Radio Nationaal hired the use of 1296 to beam its signal back to the target audience in the Netherlands and Belgium.

Current broadcasts and future plans

As part of changes caused by a cut in the BBC World Service budget, its transmissions in English on 648 kHz from Orfordness ceased on 27 March 2011.^[5]

The 648 kHz channel was brought back on air for seven weeks between 4 August and 22 September 2011 as a temporary, emergency measure for the Dutch domestic news/information network Radio 1. It was broadcast from Orfordness following fires at the Lopik and Hoogersmilde FM transmitting sites in the Netherlands on 15 July 2011.^[6][7] Following these temporary transmissions, the 648 channel once again fell silent.

Orfordness still broadcasts BBC World Service for two hours a day on 1296 kHz using the DRM digital radio system.

Also on 1296 kHz, two hours each morning (Monday to Friday) and another hour each evening (daily) are currently hired by Radio Netherlands to broadcast in Dutch. Short-lived plans by Polish Radio's external service to use 1296 from 30 October 2011 were cancelled before they were implemented.

In August 2011, the station's owners, Babcock, informed the BECTU trade union that four job posts at Orfordness were "at risk of closure", following the cut in the BBC World Service's use of the transmitters.^[8]

Transmitters

A number of transmitters have been installed on the site over the years, the most powerful being an AEG-Telefunken S4006 which has a maximum output of 600 kW. However, registration listings for both 648 and 1296 kHz have always given 500 kW as the maximum power used on both frequencies.

Transmissions on 648 kHz from the AEG-Telefunken S4006 use dynamic carrier control, an energy-saving technique in which the power of the transmitter's carrier signal is reduced when the audio level is low.

Other transmitters include two Doherty 250 kW units, designated ORF 2A and 2B (both originally at Crowborough), whose outputs can be combined to give 500 kW on a single frequency.^[9]

The newest transmitter is a 200 kW NA200 from Nautel of Canada. The NA200 (designated ORF 4) was commissioned in 2003 prior to the World Radiocommunications Conference (WRC) in Geneva, Switzerland, and was on the air for the inaugural DRM broadcasts.

Aerial systems

Aerials at Orford Ness

The station has two directional aerial systems: one for 648 kHz and one for 1296 kHz.

The directional aerial for 648 kHz (erected in 1981-82) consists of a row of five 106.7 metre (350 ft) freestanding steel lattice towers of triangular cross section, insulated at their base. All five towers are driven. It is beamed at 131 degrees (i.e. south-east) though for practical purposes the exact bearing is nominal as the beam is very broad towards the east and south. It provides daytime coverage of Belgium, the Netherlands, Luxembourg, north-east France and north-west Germany by ground wave propagation; and night-time coverage of much of Europe by skywave propagation.

The directional aerial for 1296 kHz (erected in 1978) 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. It is beamed at 96 degrees (i.e. east) and was originally mainly intended for night-time (skywave) coverage of Poland, Czechoslovakia, Hungary and the western USSR, key target areas for the BBC during the Cold War. It can also be used for daytime coverage of the Netherlands and Belgium.

Both the 648 and 1296 directional aerials have limited radiation to the west, meaning that, despite the high power of the transmitters, reception of Orfordness within the UK is poor or non-existent, with the notable exception of parts of south-east England (including London) and East Anglia.

There is also a back-up omni-directional mast radiator for 648 kHz (erected in 1983), which can only handle transmitter powers of up to 250 kW. This is only used when maintenance work is carried out on the directional antenna.

References

1. ^ Orfordness Transmitting Station, Orford, Suffolk History of the station, written in July 2011 by Andy Matheson and reproduced in Communication, monthly journal of the British DX Club, September 2011,
2. ^ [1] Kim Andrew Elliott, 13 February 2011.
3. ^ [2] BBC's German Service goes off air, BBC News, 27 March 1999.
4. ^ [3] 75 years BBC World Service - A History.
5. ^ "BBC officially announces closure of 648 kHz". Media Network. Radio Netherlands Worldwide. http://blogs.rnw.nl/medianetwork/bbc-officially-announces-closure-of-648-khz. Retrieved 10 March 2011. 
6. ^ "Dutch Radio 1 to start using 648 kHz on 4 August". Media Network. Radio Netherlands Worldwide. http://blogs.rnw.nl/medianetwork/dutch-radio-1-to-start-using-648-khz-on-4-august. Retrieved 3 August 2011. 
7. ^ Dutch Radio 1 transmissions on 648 kHz end today Media Network. Radio Netherlands Worldwide. 22 August 2011.
8. ^ Rampisham transmitter site to close by Christmas BECTU website, 18 August 2011.
9. ^ Tricks of the Trade Article by Dave Porter, Andy Matheson and Pete Edwards in Signal magazine, issue 14.

See also

• Radio masts and towers
• List of towers
• List of masts
• List of radio stations in the United Kingdom

External links

• Orfordness Nature Reserve — National Trust
• http://tx.mb21.co.uk/gallery/orfordness.php
• http://www.vimeo.com/20996209 Profile of the transmitting station and interview made in 2003 with Andy Matheson, Station Manager Orfordness, then VT Communications, now owned by Babcock.

Coordinates: 52°06′14″N 1°34′34″E / 52.10393°N 1.57614°E / 52.10393; 1.57614