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A numbers station is a type of shortwave radio station characterized by unusual broadcasts, reading out lists of numbers or incomprehensible coded messages. The voices are often created by speech synthesis and are transmitted in a wide variety of languages. The voices are usually female, although sometimes men's or children's voices are used. Some voices are synthesized and created by machines; however, some stations used to have live readers.〔(【引用サイトリンク】title=Intro to Numbers Stations )〕 Many numbers stations went off the air due to the end of the Cold War in 1989, but many still operate and some have even continued operations but changed schedules and operators. The first known use of numbers stations was during World War I, and the first possible listener was Anton Habsburg of Austria.〔(【引用サイトリンク】title=The First Numbers Stations )〕 The numbers were transmitted in Morse. The Czech Ministry of Interior and the Swedish Security Service have both acknowledged the use of numbers stations by Czechoslovakia for espionage,〔(【引用サイトリンク】title=The Swedish Security Service Released Info on a Numbers Station )〕 with declassified documents proving the same. With a few exceptions,〔stations KKN44, BFBX and OLX 〕 no QSL responses have been received from numbers stations by shortwave listeners who sent reception reports to said stations, which is the expected behavior of a non-clandestine station. The best known of the numbers stations was the "Lincolnshire Poacher", which is thought to have been run by the British Secret Intelligence Service.〔(【引用サイトリンク】title=E03 The LincolnShire Poacher )〕 In 2001, the United States tried the Cuban Five on the charge of spying for Cuba. That group had received and decoded messages that had been broadcast from Cuban numbers stations. Also in 2001, Ana Belen Montes, a senior US Defense Intelligence Agency analyst, was arrested and charged with espionage. The federal prosecutors alleged that Montes was able to communicate with the Cuban Intelligence Directorate through encoded messages, with instructions being received through "encrypted shortwave transmissions from Cuba". In 2006, Carlos Alvarez and his wife, Elsa, were arrested and charged with espionage. The U.S. District Court Florida stated that "defendants would receive assignments via shortwave radio transmissions". In June 2003, the United States similarly charged Walter Kendall Myers with conspiracy to spy for Cuba and receiving and decoding messages broadcast from a numbers station operated by the Cuban Intelligence Directorate to further that conspiracy. It has been reported that the United States used numbers stations to communicate encoded information to persons in other countries.〔 There are also claims that State Department operated stations, such as KKN50 and KKN44, used to broadcast similar "numbers" messages or related traffic. == Suspected origins and use == According to the notes of ''The Conet Project'', which has compiled recordings of these transmissions, numbers stations have been reported since World War I. If accurate, this would count numbers stations among the earliest radio broadcasts. It has long been speculated, and was argued in court in one case, that these stations operate as a simple and foolproof method for government agencies to communicate with spies working undercover. According to this theory, the messages are encrypted with a one-time pad, to avoid any risk of decryption by the enemy. As evidence, numbers stations have changed details of their broadcasts or produced special, nonscheduled broadcasts coincident with extraordinary political events, such as the August Coup of 1991 in the Soviet Union.〔The Conet Project ((included booklet )), Irdial-Discs, p. 59.〕 Numbers stations are also acknowledged for espionage purposes in Robert Wallace and H. Keith Melton's ''Spycraft'': Others speculate that some of these stations may be related to illegal drug smuggling operations.〔(【引用サイトリンク】title=Secret Radio Frequencies )〕 Unlike government stations, smugglers' stations would need to be lower powered and irregularly operated, to avoid location by triangulated direction finding. However, numbers stations have transmitted with impunity for decades, so they are generally presumed to be operated or sponsored by governments. Additionally, numbers station transmissions in the international shortwave bands typically transmit at high power levels that might be unavailable to ranches, farms, or plantations in isolated drug-growing regions. High frequency radio signals transmitted at relatively low power can travel around the world under ideal propagation conditions, which are affected by local RF noise levels, weather, season, and sunspots, and can then be received with a properly tuned antenna of adequate size, and a good receiver. However, spies often have to work only with available hand-held receivers, sometimes under difficult local conditions, and in all seasons and sunspot cycles.〔 Only very large transmitters, perhaps up to 500,000 watts, are guaranteed to get through to nearly any basement-dwelling spy, nearly any place on earth, nearly all of the time. Some governments may not need a numbers station with global coverage if they only send spies to nearby countries. A 1998 article in ''The Daily Telegraph'' quoted a spokesperson for the Department of Trade and Industry (the government department that, at that time, regulated radio broadcasting in the United Kingdom) as saying, "These (stations ) are what you suppose they are. People shouldn't be mystified by them. They are not for, shall we say, public consumption." On some stations, tones can be heard in the background. In such cases, the voice may simply be an aid to tuning to the correct frequency, with the actual coded message being sent by modulating the tones, using a technology such as burst transmission. The use of numbers stations as a method of espionage is discussed in ''Spycraft'': 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「numbers station」の詳細全文を読む スポンサード リンク
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