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PMR446



  PMR446 (Personal Mobile Radio, 446 MHz) is a radio frequency part of the UHF 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 meters (in a city) to a few kilometers (flat countryside). PMR446 is primarily used in consumer-grade walkie-talkies similar to those used for FRS/GMRS in the United States and Canada.

PMR446 usage is not generally legal in the United States; however, the standard allocation is within the range of the 440MHz band used by US amateur radio operators and in practice could be used under FCC amateur regulations. The conflicting allocations have been something of a nuisance to US amateur operators due to use of the gear by European tourists in the US.

Additional recommended knowledge

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 1st April 1998. The United Kingdom introduced PMR446 service in April 1999. 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. These radios give an additional 69 channels (LPD433) and 126 channels (SRD860) which can be used with CTCSS or DCS to eliminate cross-chat [co-channel interference]. These extra LPD and SRD channels have been introduced to reduce the burden on the 8 PMR446 channels over shorter distances (<1km).

Range

The range of the PMR446, just like any VHF or UHF radio, is dependent on many factors like environment (in city range is far less than in open field), your height above surrounding obstructions and to a very much 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 hundred meters if for example a hilltop or large metal construction is in the transmission path i.e. 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.[1]

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" [2].

Technical information

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

It is also possible to extend the range of communication by setting up a gateway between a radio and the internet using FRN or eQSO.

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).

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "PMR446". A list of authors is available in Wikipedia.
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