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Shortwave relay stations are transmitter sites used by international broadcasters to extend their coverage to areas that cannot be reached easily from their home state, for example the BBC operates an extensive net of relay stations.〔(BBC Cyprus relay. ) Retrieved 2011-04-01.〕 These days the programs are fed to the relay sites by satellite, cable/optical fiber or the Internet. Frequencies, transmitter power and antennas depend on the desired coverage. Some regional relays even operate in the medium wave or FM bands.〔(How to listen to the BBC. ) Retrieved 2011-04-01.〕 Relay stations are also important to reach listeners in countries that practice Radio jamming. Depending on the effect of the Shortwave dead zone the target countries can jam the programs only locally, e.g. for bigger cities. For this purpose Radio Free Europe/Radio Liberty with studios in Munich/Germany operated a relay station in Portugal, in the extreme west of Europe, to reach the then communist Eastern Europe.〔(Radio Free Europe. ) Retrieved 2011-04-01.〕 == Variations in design == One and only one broadcasting technology couples all of the components of a traditional shortwave relay station into one unit: the ALLISS module. For persons totally unfamiliar with the concepts of how shortwave relay stations operate this design may be the most understandable. The ALLISS module is a fully rotatable antenna system for high power (typically 500 kW only) shortwave radio broadcasting—it essentially is a self contained shortwave relay station. Most of the world's shortwave relay stations do not use this technology, due to its cost (15m EUR per ALLISS module: Transmitter + Antenna + Automation equipment). 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「Shortwave relay station」の詳細全文を読む スポンサード リンク
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