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PMR446
PMR446 (personal mobile radio, 446 MHz) is a part of the UHF radio frequency range that is open without licensing for business and personal use in most countries of the European Union. (It has roughly the same use as FRS or GMRS in the United States and Canada.) Depending on surrounding terrain range can vary from a few hundred metres (in a city) to a few kilometres (flat countryside) to many kilometres from high ground. It is ideal for small-site, same-building and line of sight outdoor activities. PMR446 is used in both professional and consumer-grade walkie-talkies (similar to those used for FRS/GMRS in the United States and Canada).
Historically, analogue FM is used but a digital voice mode has been available in radios conforming to digital private mobile radio (dPMR446) and digital mobile radio (DMR Tier 1) standards designed by ETSI.
==History==
The first steps towards creating licence-free short range radio communications were taken in April 1997 when the European Radio Communications Committee decided on a 446 MHz frequency band to be used for the new radios. In November 1998 another three decisions followed which designated the new frequency band for PMR446, established licence exemption for PMR446 equipment and established free circulation of the PMR446 equipment. The first country which introduced these frequencies for licence-free use was Ireland and it did so on 1 April 1998. The United Kingdom introduced PMR446 service in April 1999. Since 2003, PMR446 has replaced the former short-range business radio (SRBR) service. For an updated list of current status in different European countries, see the page of (European Radiocommunications Office ).
In addition to PMR446, some countries in the EU have begun to introduce LPD433 (low power device 433 MHz) licence-free short range transceiver radios as part of short range device regulations. These radios give an additional 69 channels (LPD433) which can be used with CTCSS or DCS to improve co-operation on shared channels. These extra channels have been introduced to reduce the burden on the 8 PMR446 channels over shorter distances (<1 km).
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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