PMR446: Wikis

  
  

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PMR446 (Private Mobile Radio, 446 MHz) is a part of the UHF radio frequency range that is open without licensing for personal usage 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). PMR446 is primarily used in consumer-grade walkie-talkies similar to those used for FRS/GMRS in the United States and Canada.

Contents

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 446MHz frequency band to be used for the new radios. In November 1998 another 3 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 433MHz) and SRD860 (Short Range Device 860MHz) licence-free short range transceiver radios. Both LPD433 and SRD860 are deployed as dedicated handsets and in combination with PMR446 handsets, as with the Alan 777.[1] These radios give an additional 69 channels (LPD433) and 126 channels (SRD860) which can be used with CTCSS or DCS to improve co-operation on shared channels. These extra LPD and SRD channels have been introduced to reduce the burden on the 8 PMR446 channels over shorter distances (<1 km).

Range

The range of PMR446, just like any VHF or UHF radio, is dependent on many factors like environment (in-city range is far less than in an open field), height above surrounding obstructions, and, to a lesser extent, weather conditions. The antenna type and location, transmit power and receive sensitivity also affect range. However with PMR446 most of these variables are fixed at manufacturing to comply with the PMR446 specifications.

Range may be many kilometres, e.g. from hilltop to hilltop, or only a few metres, if for example a hill or large metal object is in the transmission path between radios. The best known long distance record is 535.8 km (333 mi) from the town of Blyth in United Kingdom to the city of Almere in The Netherlands.[2]However, this was the result of enhanced propagation conditions, not a line-of-sight signal, and so is not representative.

Recently some advanced users have implemented the simplex repeater system, a cheap and easy way to extend the radio range by using extra radios connected to a small repeater controller. This is also known as "Parrot" or "ATX-2000".[3] Repeaters and gateways are prohibited in the UK. [4]

Usage worldwide

PMR446 radios use frequencies allocated to U.S. amateur radio operators. PMR446 radios can only be used in the United States under FCC amateur regulations by licensed amateur radio operators. The conflicting allocations have been something of a nuisance to U.S. amateur operators due to use of the equipment by European tourists in the U.S.

Instead, the U.S. and Canada uses the FRS system, which provides a similar service on slightly different frequencies. FRS frequencies are allocated to the emergency services in Europe, notably the fire brigade in the UK,[5] and may be subject to criminal action.

Technical information

A professional grade PMR446 radio

There are eight FM channels separated by 12.5kHz from each other. Per regulation, maximum power, like FRS, is 500mW EIRP and equipment must be handheld with a fixed antenna. CTCSS is usually used, with more upmarket models also featuring DCS.

Channel Frequency (MHz)
1 446.00625
2 446.01875
3 446.03125
4 446.04375
5 446.05625
6 446.06875
7 446.08125
8 446.09375

PMR446 gateways

PMR446 gateways extend the range of PMR446. These gateways are connected through internet using a client/server VoIP system such as eQSO or the Free Radio Network (FRN). Gateway interconnections are prohibited in the UK.

Law

References

External links








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