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Citizens Band radio (often shortened to CB radio) is a system of short-distance radio communications between individuals on a selection of 40 channels within the 27-MHz (11 m) band. In the United Kingdom, C.B. radio was first legally introduced in 1981, but had been used illegally for some years prior. In December 2006, C.B. radio was deregulated by Ofcom and it is now licence free. Although the use of C.B. radios in the UK has declined from its peak, it is still popular, especially with the farming community, Land Rover owners and Mini-Cab services. It is also fitted as standard to 'Street Glide' and 'Electra Glide' models of Harley Davidson touring motorcycles sold in the UK.〔(Touring Street Glide® | Motorcycle Touring | Harley-Davidson UK )〕 ==History== C.B. Radio was first introduced into the United Kingdom around 1972. Early use was known around the airports in the UK, particularly Stansted in 1973. As citizens band radio has been advertised in the U.S. since before 1962,〔American Radio Relay League, ''QST'', Volume XLV, 1961, February, p111.〕 it is possible that a number of these radios were brought into the U.K. and used illegally.〔Norman McLeod ''MPs put a final-twenty on CB'', ''New Scientist'', July 12, 1979 pages 92-95〕 In 1978, C.B. radio in Britain was much popularized by its use in the film ''Convoy'' and the usage of illegal C.B. radio peaked in 1980. Companies in Britain sold U.S. equipment quite openly, and equipment was readily available in car accessory shops. During this time, a great many C.B. clubs emerged in the UK and they became centres of protest in the march towards legalisation, in the hope that existing equipment could be used legally. In response to this, the government commissioned a white paper proposing a C.B. service called "Open Channel" around 860 MHz. The U.K. Government eventually legalised C.B. Radio, and on 2 November 1981 a C.B. service was introduced on a frequency band and offset that is incompatible with the imported American radios. At the same time the ownership of non-UK approved 27 MHz transceivers was made illegal except for those obtained by UK radio amateurs holding a UK "A" (HF) licence, for conversion to the 28 MHz (10 metre) amateur allocation. Given that virtually all illegal C.B. radios were contraband, this concession required the licensed amateur to pay outstanding import duty and VAT. A licence to operate these new radios became compulsory, and this could be purchased from most Post Office counters for £15. Unlike that required to qualify for a radio amateur licence, no proof of technical competence was needed. As of 8 December 2006, a licence is no longer required to own or operate a C.B. Radio providing it complies with one of the 3 type approval conditions currently permitted by Ofcom:〔(Citizen's Band Radio Information Sheet ) Ofcom website, accessed 10 April 2013〕 FM only, 4 watts power output and operating on either or both UK and CEPT (EU) 27 MHz bands only. In the early stages of the run up to the final legislation, most of the pro-C.B. lobby wanted the government to legislate around the U.S. standard C.B. system, primarily due to the large user base that already existed. The UK government made it clear from the outset that legislation for use of this equipment would be unlikely. Interference problems associated with badly calibrated amplitude modulated (AM) or Single Side Band (SSB) equipment were cited as the main factor,〔Chippindale, P. (1981, p74) ''The British CB Book'', London: Kona Publications. ISBN 0907684009〕 and it was made clear that if any system was legalised it would be frequency modulated (FM). The C.B. lobby argued that interference from AM was unlikely to occur from the use of original unmodifed AM radio equipment, a view initially rejected but later accepted by the Ministry of Defence.〔Town, R. (September, 1981) Strike Command Condemns CB. ''CB World''. Volume 1. Number 7. p6.〕 Many active and potential users continued in their insistence on a 27 MHz system, although for a locally available Citizen's Band system, the 27 MHz concept was not universally endorsed. The government initially proposed a FM system on a 928 MHz band with an RF Input power not exceeding 500 mW. This was unacceptable to the C.B. lobby partly because the low power would give a short range but mainly because the cost of equipment to operate in this band would be prohibitive. The more knowledgeable C.B. enthusiasts made a counter proposal to use a frequency around 220 MHz. This was immediately dismissed by the government who pointed out that it was a reserved military frequency band.〔Nichols, R. (1995, p20): ''The Complete CB Radio'', London: W.H. Allen & Co. ISBN 0352310146〕 It was subsequently discovered that the frequency had been unused since the Second World War. The government initially refused to relent and continued their insistence on legalising the 928 MHz band. The C.B. lobby continued to insist that any C.B. system had to use the (U.S.) 27 MHz band, be AM and a maximum output power of 4 watts (i.e. the U.S. system). Ultimately, the government hinted that they were going to give in to the C.B. lobby but, as it turned out, only up to a point. C.B. was eventually legalised on a 27 MHz band but not the band used in the U.S. Whereas the U.S. used a band occupying the range 26.965 to 27.405 MHz, the UK system was to operate on 27.60125 to 27.99125 MHz. These awkward frequencies would prevent illegal U.S. sets from being modified outside of the type approval system, though it was possible to have existing A.M. radios modified to comply with the new F.M. standard.〔Town, R. (September, 1981) Medics Need Their Ears On. ''CB World''. Volume 1. Number 7. p23.〕 The choice of frequency would also give the U.K. electronics industry a head start in the production of unique U.K. only radios. The system was FM as expected, but one initial surprise was that the power limit was set at 4 watts. The surprise was short lived when it was realised that antenna restrictions would limit the real radiated power to little more than a 500 mW system. A further restriction on power applied if the antenna was elevated by more than 7 metres from the ground. The antenna restrictions were largely ignored and, in the main, unpoliced. The government of the day had hoped that UK based manufacturers would be able to compete on a level playing field with foreign (notably Japanese) manufacturers for a share of the potential market. As it happened: the awkward choice of frequencies conspired against this ideal. The frequencies were such that, initially, only one manufacturer in Japan had the capability of producing the frequency synthesiser chips capable of producing the transmission frequencies and the local oscillator signals for use in receive mode. This manufacturer, not surprisingly, refused to supply any UK based manufacturer while it was attempting to keep Japanese manufacturers supplied. In the event, the UK market saturated within a few months and many Japanese manufacturers and UK importers were left with vast amounts of unwanted stock. Within a year of the introduction of C.B. to the UK, C.B. radio sets were being given away free with some purchase or other by many of the major retailers. In addition 20 channels in the 934 MHz band were also legalised, but equipment was considerably more expensive than the well established 27 MHz sets. At first the range was limited, but as antenna restrictions were lifted and better equipment started to appear, the number of UHF C.B. operators grew. In 1988, it was announced that the manufacture of 934 MHz equipment would be prohibited, though the use of existing equipment would remain legal. Its use largely confined to enthusiasts and amateur radio operators, the type approval specification for this band was finally withdrawn on 1 January 1999 and it is now illegal to use this equipment in the UK. An additional frequency band was introduced on 1 September 1987 giving a further 40 channels in the CEPT Band,(26.965 MHz to 27.405 MHz) also some antenna restrictions were lifted, over the past few years all antenna restrictions have been removed and planning constraints now restrict antenna size rather than regulatory compliance. It is not permitted to add the CEPT channels to existing 27/81 equipment, the only radios permitted to operate on this band are purpose made 80 channel or CEPT only sets. 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「CB radio in the United Kingdom」の詳細全文を読む スポンサード リンク
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