• The frequencies used range from 446.00625 to 446.01875MHz.
• The frequencies are divided into 8 channels:

  

Only radios to the standard PMR446 (Personal Mobile Radio on 446MHz) may be used in this portion of the UHF band.

There are on the market many models for all prices.
The radios sold in Europe are limited to 500mW.

To take full advantage of the band and be able to achieve long distances contacts (called DX), you can use other models of radios, more powerful, but it is forbidden!

Some models are reprogrammable on the UHF band, and make it possible to adapt the entire UHF band.

Most models use a coding system CTCSS which allows to create user-group.

In telecommunications, Continuous Tone-Coded Squelch System or CTCSS is a circuit that is used to reduce the annoyance of listening to other users on a shared two-way radio communications channel. Where more than one user group is on the same channel, (called co-channel users,) CTCSS filters out other users if they are using a different CTCSS tone or no CTCSS.

Example of a conventional and a reprogrammable radio:

With a reprogrammed radio, you can easily exceed 4W of transmit power, which allows you to obtain a better range than a classical radio. (Between 10 and 50Km!)
As an experiment I have already managed to make a link Mulhouse-Colmar last year with other geeks friends, and it worked!
This radio system is increasingly in vogue.
Since few months, it’s possible to buy some digital models on the internet, which enables you to encrypted the voice and send “SMS” to a radio user-group.
Here are the main differences compared with the conventional analog system: