Digital Mobile Radio (DMR) - for groups with their own communication requirements
New digital networks will have frequencies that are allocated for this purpose. However, if you have an analogue network and wish to convert to a digital network you do not have to apply for new frequencies and only have to send notice of the change to Nkom.
The frequency band should be chosen based on the communication lines you wish to cover.
Frequencies on the VHF band provide good range in hilly terrain and this is the frequency band that is used most for PMR (Professional Mobile Radio). Hunting and security radio and maritime VHF are examples of users on this frequency band. Fire, police and health services also use VHF, however are in the process of transferring to the new emergency network which uses the TETRA technology on a different frequency band.
Communication on these frequencies is particularly well-suited for those who require indoor lines in concrete structures such as a building site. The range can be found to be somewhat shorter than VHF communication outdoors, however UHF ensures good local communication if the surroundings are difficult.
Digital and analogue PMR
One can choose between the traditional analogue system and newer digital system.
- The networks are mobile radio communication networks for internal use for a limited group with their own communication needs.
- The networks can use both one-to-one or one-to-many communication. In one-to-many communication, everyone on the radio communication network will hear what is being said over the network.
- PMR networks are geographically restricted.
Benefits of digital PMR networks
The use of the digital PMR networks is becoming increasingly more common and there have been major developments in this area Digital radio has many benefits:
- Encryption of the radio communication prevents wiretapping
- Better voice quality
- Messages can be sent internally on the radio network.
- Conference calls or private calls
- Possibility of "linking" bases via IP
- Digital and analogue channels on the same radio
The traditional analogue communication radios are of course still relevant and can be set up in several different ways with everything from individual needs to more advanced solutions with 5-tone selective calling number on each radio.
Terrestrial trunked radio (TETRA) is a standard for digital radio systems for closed, group-oriented radio communication that is specially development for public emergency response services, however is also used by other professional users, particularly within the transport sector, Armed Forces and other previous major users of PMR.
The emergency network that is being developed in Norway is an example of a communications network that uses TETRA technology. The emergency network is administered by the Directorate for Emergency Communication.