Droitwich AM transmitter
Encyclopedia
Longwave
In radio, longwave refers to parts of radio spectrum with relatively long wavelengths. The term is a historic one dating from the early 20th century, when the radio spectrum was considered to consist of long, medium and short wavelengths...
and mediumwave
Mediumwave
Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz...
transmissions, established in 1934 in the civil parish of Dodderhill
Dodderhill
Dodderhill is a village and civil parish, near Droitwich, Worcestershire, England, located on the River Salwarpe. The parish is bisected by the M5 motorway, constructed in 1962...
, just outside the village of Wychbold
Wychbold
Wychbold is a village in the Wychavon district of Worcestershire, England. It is by junction 5 of the M5, and is on the A38 north-east of Droitwich, near to where they cross the River Salwarpe. Just outside the village on the A38 is Webbs of Wychbold, one of the UK's largest garden centres....
, which is near Droitwich, Worcestershire
Worcestershire
Worcestershire is a non-metropolitan county, established in antiquity, located in the West Midlands region of England. For Eurostat purposes it is a NUTS 3 region and is one of three counties that comprise the "Herefordshire, Worcestershire and Warwickshire" NUTS 2 region...
, 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...
. This transmission site is the location of the British Broadcasting Corporation
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
's most powerful longwave transmitter, which together with the two Scottish longwave transmitters at Burghead and Westerglen forms a network broadcasting on the same frequency. The masts can be seen to the east from the M5 motorway
M5 motorway
The M5 is a motorway in England. It runs from a junction with the M6 at West Bromwich near Birmingham to Exeter in Devon. Heading south-west, the M5 runs east of West Bromwich and west of Birmingham through Sandwell Valley...
, between Droitwich and Bromsgrove
Bromsgrove
Bromsgrove is a town in Worcestershire, England. The town is about north east of Worcester and south west of Birmingham city centre. It had a population of 29,237 in 2001 with a small ethnic minority and is in Bromsgrove District.- History :Bromsgrove is first documented in the early 9th century...
. At night, the two sets of aircraft warning lights
Aircraft warning lights
Aircraft warning lights are high-intensity lighting devices that are attached to tall structures and are used as collision avoidance measures. Such devices make structures more visible to passing aircraft and are usually used at night, although they may be used during the day as well...
are visible from a long distance. The station is owned and operated by Arqiva
Arqiva
Arqiva is a telecommunications company which provides infrastructure and broadcast transmission facilities in the United Kingdom and Republic of Ireland. The present company, with headquarters located at Crawley Court in the village of Crawley, Hampshire, was formed by National Grid Wireless...
.
Technical specifications
The frequency was 200 kHz until February 1988 when it was changed to 198 kHz, and the power currently 500 kW. The carrier frequency is controlled by a rubidiumRubidium
Rubidium is a chemical element with the symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the alkali metal group. Its atomic mass is 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other elements in group 1, such as very rapid...
atomic frequency standard
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
in the transmitter building, enabling the transmission to be used as an off-air frequency standard. For the long-wave transmission, a T-aerial
T-aerial
A T-aerial is an antenna used for VLF, LF, MF and shortwave transmission or reception.It consists of a horizontal wire suspended between two radio masts or towers. A vertical wire is connected to the middle of the horizontal wire and hangs down close to the ground, where it is connected to the...
is used, which is suspended between two 700 ft (210 m) high guyed steel lattice masts
Radio masts and towers
Radio masts and towers are, typically, tall structures designed to support antennas for telecommunications and broadcasting, including television. They are among the tallest man-made structures...
, which are 600 ft (180 m) apart from each other.
There are also two guyed mast radiator
Mast radiator
A mast radiator is a radio mast or tower in which the whole structure itself functions as an antenna. This design is commonly used for transmitting antennas operating at low frequencies, in the VLF, LF and MF ranges, in particular those used for AM broadcasting. The metal mast is electrically...
s at the site, which are used for transmitting AM medium-wave radio programmes on 693 kHz, 1053 kHz and 1215 kHz.
Transmissions
A number of items in the BBC Radio 4 schedule are carried on the longwave frequency only: these include Yesterday In Parliament at 0835–0900 on Tuesdays to Fridays, The Daily ServiceThe Daily Service
The Daily Service is a short Christian church service, often from Emmanuel Church in Didsbury, Manchester, England, broadcast every weekday morning between 9.45 and 10.00 by BBC Radio 4 and on the Radio 4 DAB breakout. For many years it was broadcast live from All Souls Church, Langham Place, the...
at 0945–1000 on Mondays to Fridays, the Shipping Forecast
Shipping Forecast
The Shipping Forecast is a four-times-daily BBC Radio broadcast of weather reports and forecasts for the seas around the coasts of the British Isles. It is produced by the Met Office and broadcast by BBC Radio 4 on behalf of the Maritime and Coastguard Agency. The forecasts sent over the Navtex...
at 1201–1204 daily and 1754–1757 on Mondays to Fridays, and Test Match Special
Test Match Special
Test Match Special is a British radio programme covering professional cricket, broadcast on BBC Radio 4 , Five Live Sports Extra and the internet to the United Kingdom and the rest of the world...
during international cricket games.
The Radio 4 LW signal also carries radio data encoded using phase modulation
Phase modulation
Phase modulation is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave.Unlike its more popular counterpart, frequency modulation , PM is not very widely used for radio transmissions...
, giving a time-of-day signal, and control signals for Economy 7
Economy 7
Economy 7 is the name of a differential tariff provided by United Kingdom electricity suppliers that uses base load generation to provide cheap off-peak electricity during the night....
electric heating systems.
Radio Five Live is broadcast on 693 kHz, which apart from Brookmans Park
Brookmans Park Transmitter
The Brookmans Park transmitting station is a facility for medium wave broadcasting north of London . The station was built by the BBC as the first of a network of regional dual transmitter stations, replacing the city based ones used previously, and this was to cover the Home Counties, London and...
and Moorside Edge
Moorside Edge Transmitter
Moorside Edge, originally constructed in 1931 to radiate the BBC's "North Regional" and "National" programmes ., has one of the most powerful mediumwave radio transmitters in Britain at 200 kW erp. Formed of two 158 m steel lattice towers it is located just above Moorside Edge...
, is one of the strongest signals in the UK, covering most of the Midlands and Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
.
During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
secret messages were sent to the French Resistance using the transmitter. The messages were read during normal programme broadcasts.
In 2011 as part of the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
cuts it was announced that there would be no re-investment in Longwave
Longwave
In radio, longwave refers to parts of radio spectrum with relatively long wavelengths. The term is a historic one dating from the early 20th century, when the radio spectrum was considered to consist of long, medium and short wavelengths...
which will mean an eventual end to BBC Radio 4
BBC Radio 4
BBC Radio 4 is a British domestic radio station, operated and owned by the BBC, that broadcasts a wide variety of spoken-word programmes, including news, drama, comedy, science and history. It replaced the BBC Home Service in 1967. The station controller is currently Gwyneth Williams, and the...
on Longwave. It was later announced that the transmitter relies on a pair of metre-high glass valves that last between 1 and 10 years and there were less than 10 remaining in the world and it is not possible to manufacture new ones.
Reception
The Radio 4BBC Radio 4
BBC Radio 4 is a British domestic radio station, operated and owned by the BBC, that broadcasts a wide variety of spoken-word programmes, including news, drama, comedy, science and history. It replaced the BBC Home Service in 1967. The station controller is currently Gwyneth Williams, and the...
LW signal from Droitwich is by far the strongest in the UK, covering most of England and Wales, the Benelux, parts of West Germany (covering the areas where the British Forces in Germany are based) and Northern France. There are supplementary medium-wave transmitters in London, South West England, Newcastle area, Carlisle area, Scotland, Wales and Northern Ireland. The BBC had wanted to drop Radio 4 on LW, but was forced to retreat after widespread criticism from long-wave 'die-hards' Radio 4 Long Wave Campaign (including listeners in Ireland and Northern France). The long wave signal is very popular among British expats in North West Europe.
The longwave signal on 198 kHz, BBC Radio 4, can be received on the flight deck
Cockpit
A cockpit or flight deck is the area, usually near the front of an aircraft, from which a pilot controls the aircraft. Most modern cockpits are enclosed, except on some small aircraft, and cockpits on large airliners are also physically separated from the cabin...
with the ADF nav receiver
AM broadcasting
AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...
while flying the North Atlantic (NAT
North Atlantic Tracks
North Atlantic Tracks are trans-Atlantic routes that stretch from the northeast of North America to western Europe across the Atlantic Ocean. They ensure aircraft are separated over the ocean, where there is little radar coverage...
) as far west as 30°W.
Channels available
| Frequency | kW | Service |
|---|---|---|
| 198 kHz | 500 | BBC Radio 4 BBC Radio 4 BBC Radio 4 is a British domestic radio station, operated and owned by the BBC, that broadcasts a wide variety of spoken-word programmes, including news, drama, comedy, science and history. It replaced the BBC Home Service in 1967. The station controller is currently Gwyneth Williams, and the... |
| 693 kHz | 150 | BBC Radio 5 Live BBC Radio 5 Live BBC Radio 5 Live is the BBC's national radio service that specialises in live BBC News, phone-ins, and sports commentaries... |
| 1053 kHz | N/A | Talksport TalkSPORT Talksport , owned by UTV radio, is one of the United Kingdom's three terrestrial analogue Independent National Radio broadcasters, offering a sports and talk radio service broadcast from London to the United Kingdom.... |
| 1215 kHz | N/A | Absolute Radio |
See also
- List of masts
- List of tallest buildings and structures in Great Britain
- List of radio stations in the United Kingdom
- Radio teleswitchRadio teleswitchA Radio Teleswitch is a device used in the United Kingdom to allow electricity suppliers to switch large numbers of electricity meters between different tariffs, by broadcasting an embedded signal in broadcast radio signals...
- LongwaveLongwaveIn radio, longwave refers to parts of radio spectrum with relatively long wavelengths. The term is a historic one dating from the early 20th century, when the radio spectrum was considered to consist of long, medium and short wavelengths...
DXingDXingDXing is the hobby of tuning in and identifying distant radio or television signals, or making two way radio contact with distant stations in amateur radio, citizens' band radio or other two way radio communications. Many DXers also attempt to receive written verifications of reception from the... - Non-directional beaconNon-directional beaconA non-directional beacon is a radio transmitter at a known location, used as an aviation or marine navigational aid. As the name implies, the signal transmitted does not include inherent directional information, in contrast to other navigational aids such as low frequency radio range, VHF...
- Automatic direction finder (ADF)
- Radio navigationRadio navigationRadio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...