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The Mendip transmitting station is a broadcasting and telecommunications facility, situated on the summit of Pen Hill, part of the Mendip Hills range in Somerset, England, at above sea level. The station is located in St Cuthbert Out civil parish in Mendip district, approximately from the centre of Wells. It includes a tall mast, which was built in 1967 and weighs around 500 tonnes, and is the tallest structure in South West England. The mast broadcasts digital television, FM analogue radio and DAB digital radio, and had broadcast analogue colour television from 1967 until 2010. Until 2008 a GRP aerial cylinder, which contains the analogue television transmitting antennas, was located at the top of the mast, bringing the total height of the structure to . With a mean height of above sea level, the analogue television antennas were amongst the highest in the UK. The analogue television antennas were removed in 2010, the original antenna cylinder being replaced with a new antenna assembly, ready for digital switchover in 2010. The new assembly is slightly shorter than the previous cylinder causing the overall mast height to be reduced from to .〔(Planning Application Details )〕 There are red aircraft warning lamps (six sets of two lights) up the mast with two lights on top. The lights were upgraded in February 2007〔http://www.cheddarvalleygazette.co.uk/displayNode.jsp?nodeId=216909&command=displayContent&sourceNode=216903&contentPK=16636764&moduleName=InternalSearch&formname=filtersearch〕 to comply with CAA 2000 Air Navigation Order, designed to prevent low flying aircraft from hitting the mast. The station is owned and operated by Arqiva (which acquired the National Grid Wireless, previously Crown Castle.) The mast was repainted during 2007. The mast has become a Mendip landmark, providing a method of identifying the hills from a distance. ==Television== Mendip was set up as a C/D group transmitter when it entered service with analogue PAL transmissions. In July 2007, Ofcom confirmed that it would remain a C/D group transmitter at digital switchover. The mast broadcasts digital television over a large area of the west of England, including Somerset, Wiltshire, North Somerset, Bath and North-East Somerset, Bristol, South Gloucestershire and Southern Gloucestershire. The station also covers the coastal areas of south east Wales, and in the days of analogue TV, many households used it in preference to their more local station, Wenvoe. This is because prior to the digital switchover, Mendip carried Channel 4 and Channel 5, whereas Wenvoe only carried S4C, which broadcast a lot of Welsh language programming. Power on analogue transmissions was 500 kW (erp) on channels 1 to 4 and 126 kW on Channel 5. The latter was transmitted outside of the original C/D grouping of the transmitter but most people in reasonable signal areas could receive it anyway, (see aerial gain curves ). All six digital multiplexes were transmitted at 10 kW until switchover in 2010 when the power on the "BBC A", "BBC B/HD" and "D3&4" multiplexes was boosted to 100 kW. In 2011, SDN was boosted to 50 kW and in 2012 the remaining two Arqiva multiplexes will be boosted to 50 kW too. Mendip's population coverage is around 1.5 million, although some homes in the immediate vicinity, such as those in Cheddar are unable to receive a signal due to being in the shadow of the Mendip Hills and therefore have to depend on local relays. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mendip transmitting station」の詳細全文を読む スポンサード リンク
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