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Scanner (radio)
Uniden BCT-15 base/mobile trunktracking scanner 
Uniden BCD396T handheld trunktracking scanner
History and useScanners developed from earlier tunable and fixed-frequency radios that received one frequency at a time. Non-broadcast radio systems, such as those used by public safety agencies, do not transmit continuously. With a radio fixed on a single frequency, much time could pass between transmissions, while other frequencies might be active. A scanning radio will sequentially monitor multiple programmed channels, or search between user defined frequency limits. The scanner will stop on an active frequency strong enough to break the radio's squelch setting and resume scanning other frequencies when that activity ceases. Scanners are used by hobbyists, railfans, off duty emergency services personnel and reporters. Scanners first became popular and widely available during CB Radio's heyday in the 1970s. The first scanners often had between four and ten channels and required the purchase of a separate crystal for each frequency received. Modern programmable scanners allow hundreds or thousands of frequencies to be entered via a keypad and stored in various 'memory banks' and can scan at a rapid rate due to modern microprocessors. 
A hand-held wide band communications receiver. Some scanners are equipped with Fire-Tone out. Fire tone out decodes Quik call II tones and acts as a pager when the correct sequence of tones is detected. Active frequencies can be found by searching the internet and frequency reference books or can be discovered through a programmable scanner's search function. An external antenna for a desktop scanner or an extendable antenna for a hand held unit will provide greater performance than the original equipment antennas provided by manufacturers. Legal issues
A law passed by the Congress of the United States, under the pressure from cellular telephone interests, prohibited scanners sold after a certain date from receiving frequencies allocated to the Cellular Radio Service. The law was later amended to make it illegal to modify radios to receive those frequencies, and also to sell radios that could be easily modified to do so.http://www.fcc.gov/Bureaus/Engineering_Technology/Public_Notices/1997/da971440.txt This law remains in effect even though few cellular subscribers still use analog technology. There are Canadian and European unblocked versions available, however these are illegal to import into the U.S. Frequencies used by early cordless phones at 43.720--44.480, 46.610--46.930 MHz and 902.000 ? 906.000 MHz can be picked up by many scanners. The proliferation of scanners led most cordless phone manufacturers to produce cordless handsets operating on a more secure 2.4 GHz system using spread-spectrum technology. Certain states in the U.S., such as New York and Florida, prohibit the use of scanners in a vehicle unless the operator has a radio license issued from the FCC (Amateur Radio, etc)[1] [2] or the operator's job requires the use of a scanner in a vehicle (ie, Police, Fire, Utilities) In the United Kingdom and France, it is illegal to listen to almost anything outside the amateur radio and broadcast bands. Canada allows any analog transmission to be monitored but content of the communication may not be disclosed. In some parts of the United States, there are extra penalties for the possession of a scanner during a crime, and some states, such as Michigan, also prohibit the possession of a scanner by a person who has been convicted of a felony in the last 5 years. [3] Other countries consider possession of a scanner at any time an offense. In the United States, the general guidelines to follow when using a radio scanner are that it is illegal to:
A partial copy of the Electronic Communications Privacy Act of 1986 can be found here: "Electronic Communications Privacy Act of 1986" Example laws by country
See also
ReferencesExternal linksRadio Frequency SourcesThere are numerous websites which provide lists of frequencies for emergency services and businesses in various areas of the world. These are among the most prominent.
Scanner Manufacturers
Scanner Laws
Other links
da:Skanner (radio) de:Funkscanner it:Ricevitore scanner nl:Scanner (radio) fi:Skanneriradio sv:Scanner (mottagare) Source: Wikipedia | The above article is available under the GNU FDL. | Edit this article
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