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Digital Mobile Radio (DMR) has three defined tiers, or levels, that allow manufacturers to develop equipment for different types of users. Some users may only need a simple system where every radio can communicate with every other radio, while aid organizations need an encrypted network with national coverage and remote programming. The different tiers are discussed below.
What is DMR Tier 1?
DMR Tier I is a series of DMR frequencies designated by the European Telecommunications Standards Institute (ETSI) for license-free use in the European Union.
DMR Tier I defines 16 channels for DMR use between 446 MHz and 446.2 MHz. This gives everyone the opportunity to purchase radios that are compatible with Tier I and start using them immediately.
Tier I also defines that the maximum power of each radio must be less than 500 mW. Most popular models have a maximum power of 5 W (10 times as much) for comparison.
The 16 DMR Tier I frequencies are not assigned to specific users, so users of devices on this frequency may experience nuisance from other users in the environment. This can cause problems if communication does not work well in business-critical situations.
It is therefore important to consider these risks when purchasing DMR Tier I equipment.
What is DMR Tier 2?
DMR Tier II radio equipment can operate anywhere in the DMR frequency range, but usually does so between the 136-174 MHz band for VHF and 403 - 527 for UHF.
DMR Tier II equipment requires a license from the authority issuing it in your country to use the equipment. The advantage of this is that there are no problems with other users interfering with your communication, as well as avoiding the low power of Tier I equipment.
DMR Tier II equipment can use repeater stations to extend the range of the system. This allows you to build a radio infrastructure to meet all your geographic needs.
What is DMR Tier 3?
DMR Tier III radio equipment works within the same frequency range as Tier II equipment, but has the additional advantage that all kinds of extra functionalities are possible to adapt the system to your situation.
DMR Tier III equipment operates in the so-called '' Trunked mode ''. This means that radios are automatically assigned to specific frequencies, instead of being on a fixed frequency.
Trunking allows you to license fewer frequencies to establish the same amount of communication. Automatic frequency allocation prevents the possibility of two groups trying to communicate on the same frequency. This is of increasing importance with larger systems.
DMR Tier III also adds additional data capabilities, enabling the radios to use SMS messages, location services (GPS), telemetry data, remote programming, as well as remote control. Even radios that have been forgotten to turn off can be turned off remotely.