|
Rampisham Down is a chalk hill in the Dorset Downs, eight miles north west of Dorchester in west Dorset, England. The highest part of the hill is 221 metres (720 feet). To the north east of the hill is the Frome valley and the village of Rampisham, to the south west is the Hooke valley and the village of Hooke. The A356 road between Dorchester and Crewkerne cuts across the down. ==Communications station== Rampisham Down was the location of one of the main transmitters of the BBC World Service in Europe until it was shut in 2011. There were 26 transmitter pylons on the down. The station was operated by Babcock International Group as part of the takeover of VT Group (formerly VT Communications and Merlin Communications following the privatisation of BBC Transmission Services in 1997). The 189-acre site was acquired by the BBC in November 1939 and the station, known as Overseas Extension 3 (OSE3), was equipped with four Marconi type SWB 18, 100 kW short-wave transmitters. The transmitter halls, each containing a pair of these transmitters, were separated by heavy blast walls. A comprehensive aerial system was installed consisting of 29 arrays supported between 15 masts of heights varying between l00 ft and 325 ft. Full world coverage was given by this aerial system, although the transmissions were primarily intended for areas outside Europe. This was the first of the BBC' s short-wave stations to be provided with 4-wire transmission lines, following tests made at Daventry (OSE1). A remotely controlled switching tower was used for connecting any transmitter to any aerial array (antenna). OSE3 was provided with an emergency power supply consisting of two 750-bhp diesel alternator sets. The diesel engines, which had been designed for railway locomotives abroad, were equipped with battery starting facilities instead of the compressed-air starting arrangements that were conventional for diesel engines of this size. The station came into service on 16 February 1941 and during May of that year a number of tests were carried out using a captive balloon to measure the performance of the horizontal dipole arrays and to determine the effect of the contour of the ground close to the station on their vertical radiation pattern. During those first years the site was subject to attempts at destruction by the German Luftwaffe. Mr E.A. Beaumont, who was part of the original installation team writes..' I have vivid recollections of my colleagues during these years when we completed the installation and putting into service of the station to the accompaniment of the Luftwaffe's efforts to put southern England out of action and I can still recall the line of craters left on the north side of the road opposite the station by a stick of bombs deposited by a German bomber one night and the cannon shells which penetrated the diesel generator building on another occasion. Aerial dog fights between large formations of German bombers and our defending fighters became a daily occurrence and our wives had to put up with hit and run bombing raids in Bridport itself ‘. The original transmitters remained in service until 1963 when they were replaced by 250 kW transmitters built by Marconi along with two twin-channel 100 kW units. About three years later the first of the BBC's relay stations overseas was built on Ascension Island and in order to provide a programme feed to the island two 60 kW Single Side Band transmitters were installed at Rampisham. This method of sending programme feeds to the relay stations continued until satellite feeds became available. In 1982 Rampisham went through the biggest re-engineering since it began. The site was completely stripped of the old antennas and the building gutted to a shell in preparation for a complete new installation. Ten 500 kW transmitters and 34 wideband curtain arrays were installed. The majority of antennas point in an Easterly direction with others capable of beaming to the West. A fully automatic control system was also installed that continually monitored the broadcasts and the site. Following extensive budget cuts by the BBC World Service, due to the ceasing of funding by the Foreign & Commonwealth Office, the site was earmarked for closure in Summer 2011. The final broadcast from the site took place on Saturday 29 October 2011. Sender 48 was the final transmitter on-air, broadcasting Deutsche Welle's German service to Europe on 6075 kHz between 21:00 and 21:59. This was the final Deutsche Welle broadcast to Europe. The final BBC transmissions were in Arabic between 20:00 and 21:00 on 5790 kHz and 11680 kHz to North Africa. File:View of Rampisham transmitter site, Dorset, England.jpg|View of the Buildings File:AppRm.jpg|Apparatus Room File:SenderAEG.jpg|Valve in AEG S4005 Transmitter File:Rampisham sunset.jpg|Antenna Field 1 File:Rampisham snow2.jpg|Antenna Field 2 File:ICYArrays3.jpg|Antenna Field 3 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「Rampisham Down」の詳細全文を読む スポンサード リンク
|