Audio Surveillance
"Bugging" - audio surveillance - of corporations, governments, embassies,
individuals' homes, offices or telephone lines - allows very efficient
surveillance (cheap devices are available in shops or via mail-order), and is
therefore very common and popular.
Modern snoopers do not need more than an adapted powerful laptop to tune in to
all the mobile phones active in a certain area by simply scrolling lists of
numbers. The world's biggest and most powerful eavesdropping system is
"Echelon", mainly controlled by the USA's National Security Agency NSA. The NSA
is capable of intercepting telephone, fax, wireless, and e-mail communication
worldwide and holds various patents in natural language processing of high tech
voice recognition and text extraction systems.
To demonstrate the power of interception devices, World-Information.Org has
installed a parabolic microphone together with a typical surveillance camera on
the balcony, which allows eavesdropping on the nearby bus stop and restaurant.
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Source: http://world-information.org/wio/program/objects/993045260