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SIGINT is a contraction of SIGnals INTelligence. Before the development of radar and other electronics techniques, signals intelligence and communications intelligence (COMINT) were essentially synonymous. Sir Francis Walsingham ran a postal interception bureau with some cryptanalytic capability during the reign of Elizabeth I, but the technology was only slightly less advanced than men with shotguns, during World War I, who jammed pigeon post communications and intercepted the messages carried. Flag signals were sometimes intercepted, and efforts to impede them made the occupation of the signaller one of the most dangerous on the battlefield. The middle 19th century rise of the telegraph allowed more scope for interception and spoofing of signals, as shown at Chancellorsville. Signals intelligence became far more central to military (and to some extent diplomatic) intelligence generally with the mechanization of armies, development of blitzkrieg tactics, use of submarine and commerce raiders warfare, and the development of practicable radio communications. Even Measurement and Signature Intelligence (MASINT) preceded electronic intelligence (ELINT), with sound ranging techniques for artillery location. SIGINT is the analysis of intentional signals for both communications and non-communications (e.g., radar) systems, while MASINT is the analysis of unintentional information, including, but not limited to, the electromagnetic signals that are the main interest in SIGINT. ==Origins== Electronic interception appeared as early as 1900, during the Boer Wars. The Royal Navy had installed wireless sets produced by Marconi on board their ships in the late 1890s and some limited wireless signalling was used by the British Army. Some wireless sets were captured by the Boers, and were used to make vital transmissions. Since the British were the only people transmitting at the time, no special interpretation of the signals was necessary. The Imperial Russian Navy also experimented with wireless communications under the guidance of Alexander Popov, who first installed a wireless set on a grounded battleship in 1900. The birth of signals intelligence in a modern sense dates to the Russo-Japanese War. As the Russian fleet prepared for conflict with Japan in 1904, the British ship HMS ''Diana'' stationed in the Suez canal was able to intercept Russian naval wireless signals being sent out for the mobilization of the fleet, for the first time in history. "An intelligence report on signals intercepted by HMS ''Diana'' at Suez shows that the rate of working was extremely slow by British standards, while the Royal Navy interpreters were particularly critical of the poor standard of grammar and spelling among the Russian operators".〔''Report from HMS Diana on Russian Signals intercepted at Suez'', 28th January 1904, Naval library, Ministry of Defence, London.〕 The Japanese also developed a wireless interception capability and succeeded in listening in to the then primitive Russian communications. Their successes emphasized the importance of this new source of military intelligence, and facilities for the exploitation of this information resource were established by all the major powers in the following years. The Austro-Hungarian Evidenzbureau was able to comprehensively monitor the progress of the Italian army during the Italo-Turkish War of 1911 by monitoring the signals that were sent by a series of relay stations from Tripoli to Rome. In France, Deuxième Bureau of the Military General Staff was tasked with radio interception. 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「Signals intelligence in modern history」の詳細全文を読む スポンサード リンク
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