|
A radio jammer is any device that deliberately blocks, jams or interferes with authorized wireless communications.〔http://www.fcc.gov/document/consumer-alert-using-or-importing-jammers-illegal Enforcement Advisory No. 2012-02 FCC ENFORCEMENT ADVISORY CELL JAMMERS, GPS JAMMERS, and OTHER JAMMING DEVICES CONSUMER ALERT: Using or Importing Jammers is Illegal〕 In America and many other places, jammers are illegal and their use can result in large fines. In some cases jammers work by the transmission of radio signals that disrupt communications by decreasing the signal-to-noise ratio. The concept can be used in wireless data networks to disrupt information flow.〔(NIST 800-97 Establishing Wireless Robust Security Networks: A Guide to IEEE 802.11i )〕 It is a common form of censorship in totalitarian countries, in order to prevent foreign radio stations in border areas from reaching the country.〔 As an example, Islamic regime in Iran has been using the radio jamming to block free information across the large cities and the capital, Tehran. Jamming is usually distinguished from interference that can occur due to device malfunctions or other accidental circumstances. Devices that simply cause interference are regulated under different regulations. Unintentional 'jamming' occurs when an operator transmits on a busy frequency without first checking whether it is in use, or without being able to hear stations using the frequency. Another form of unintentional jamming occurs when equipment accidentally radiates a signal, such as a cable television plant that accidentally emits on an aircraft emergency frequency. ==Distinction between "jamming" and "interference"== Originally the terms were used interchangeably but nowadays most radio users use the term "jamming" to describe the ''deliberate'' use of radio noise or signals in an attempt to disrupt communications (or prevent listening to broadcasts) whereas the term "interference" is used to describe ''unintentional'' forms of disruption (which are far more common). However the distinction is still not universally applied. For inadvertent disruptions, see electromagnetic compatibility. 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「radio jamming」の詳細全文を読む スポンサード リンク
|