|
Shortwave radio is radio transmission using shortwave frequencies, generally 1.6–30 MHz, just above the medium wave AM broadcast band. Shortwave radio is used for long distance communication by means of ''skywave'' or ''skip'' propagation, in which the radio waves are reflected or refracted back to Earth from the ionosphere, allowing communication around the curve of the Earth. Shortwave radio is used for broadcasting of voice and music, and long-distance communication to ships and aircraft, or to remote areas out of reach of wired communication or other radio services. Additionally, it is used for two-way international communication by amateur radio enthusiasts for hobby, educational and emergency purposes. ==Frequency classifications== The widest popular definition of the shortwave frequency interval is the ITU Region 1 (EU+Africa+Russia...) definition, and is the span 1.6–30 MHz, just above the medium wave band, which ends approximately at 1.6 MHz. There are also other definitions of the shortwave frequency interval: * 1.71 to 30 MHz in ITU Region 2 (North and South America...) * 1.8 (160 meter radio amateur band start) to 30 MHz * 2.3 (120 meter band start) to 30 MHz * 2.3 (120 meter band start) to 26.1 MHz (11 meter band end)〔Inconsistent article: (itwissen.info: KW (Kurzwelle) SW (short wave) ) Quote: "... Der KW-Frequenzbereich (SW) liegt zwischen 3 MHz und 30 MHz () ... Kurzwelle ist auch eine sendetechnische Bezeichnung für Rundfunk im Frequenzbereich zwischen 2,3 MHz und 26,1 MHz () ..."〕〔(oldtimeradio.de: Kleines Radio-Lexikon ) Quote: "... Kurzwellen, Kurzwellenbereich ... Wellenbereich, der von den Rundfunksendern (je nach geographischer Lage) von 11 bis 120 m = 26.100 bis 2.300 kHz ..."〕 * In Germany and perhaps Austria the ITU Region 1 shortwave frequency interval can be subdivided in: * * '':de:Grenzwelle'' ("border waves"): 1.605-3.8 MHz and '':de:Kurzwelle'' (shortwaves) 3.8-30 MHz〔(darc.de: Amateurfunk Frequenzen ) Quote: "... Grenzwelle (Kurzwelle) ...", '':de:Grenzwelle'' Quote: "... Als Grenzwelle wird der Frequenzbereich zwischen 1605 kHz und 3800 kHz bezeichnet, weil er auf der „Grenze“ zwischen Mittelwelle und Kurzwelle liegt ..."〕 * * ''Grenzwelle'': 1.605-4 MHz and ''Kurzwelle'' (shortwaves) 4-30 MHz * In Germany these shortwave frequency intervals has also been seen used: * * 3-30 MHz〔Inconsistent article: (Die Meterbänder der Kurzwelle ) Quote: "...Bereich der Kurzwelle von 3.000 kHz bis 30.000 kHz ... () ... 120 m ... 2.300 kHz ... 2.495 kHz ... Tropenband ..."〕〔(Universal-Lexikon: Kurzwellen ) Quote: "... entsprechend Frequenzen von 30-3 MHz ..."〕 – e.g. some accept that “high frequency” is the same as “short wave”. In reality, the definition of the “shortwave” frequency band is a mess, and therefore the “shortwave frequencies” can not be exactly equal “high frequencies”. * * the above other definitions〔(Grundig Satellit 1000 TR6002 ), (schematic ) See at the bottom of the schematic, just below the transformer. In the schematic it is written that the first shortwave band starts at 1.6 MHz (just after the band end of MW/AM): "KW1-SW1-OC1 1,6 .... 5,0 MHz"〕 Shortwave radio received its name because the wavelengths in this band are shorter than 200 m (1500 kHz) which marked the original upper limit of the medium frequency band first used for radio communications. The broadcast medium wave band now extends above the 200 m/1500 kHz limit, and the amateur radio 1.8 MHz – 2.0 MHz band (known as the "top band") is the lowest-frequency band considered to be 'shortwave'. 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 radio」の詳細全文を読む スポンサード リンク
|
