DMR and its three tiers
DMR (Digital Mobile Radio) is the open digital radio standard developed by ETSI. It uses time division multiple access (TDMA) to carry two simultaneous calls on the same 12.5 kHz channel, doubling capacity compared to analog systems. Over analog, DMR delivers better audio quality, lower battery consumption in portable radios, text messaging, and GPS location tracking.
The standard is structured in three tiers, each designed for a distinct operational context.
DMR Tier I: license-free communication
Tier I covers the PMR446 band at 446 MHz, accessible in Europe without a license at up to 0.5 W with a fixed, non-removable integrated antenna. It is the choice for short-range use with no dedicated infrastructure — retail, small construction sites, events, and recreational activities.
| Parameter | Value |
|---|---|
| Band | 446 MHz (PMR446) |
| Maximum power | 0.5 W |
| Channels | 16 digital channels |
| Typical coverage | 1–2 km |
| License | Not required |
DMR Tier II: conventional licensed systems
Tier II is the professional tier operating on licensed frequencies. It covers VHF (136–174 MHz) and UHF (403–527 MHz) bands at up to 50 W. The two-slot TDMA scheme doubles the capacity of each assigned frequency. It supports encryption, data messaging, and GPS tracking.
This is the standard choice for businesses, private security, transport, utilities, and industry that need wide-area coverage with a conventional infrastructure.
| Parameter | Value |
|---|---|
| Bands | VHF 136–174 MHz / UHF 403–527 MHz |
| Maximum power | 50 W |
| Multiplexing | TDMA — 2 slots per 12.5 kHz channel |
| License | Required |
DMR Tier III: trunked systems
Tier III adds trunking: a central controller dynamically allocates available channels to active calls, reducing wait times and maximizing spectrum utilization. It supports thousands of users, priority calls, group calls, and advanced security features including encryption and authentication. It is the tier chosen by government agencies, large enterprises, and emergency services managing networks with high traffic volumes.
DMR tier comparison
- Licenza
- Senza licenza
- Modalità operativa
- Simplex
- Banda di frequenza
- 446 MHz
- Potenza di uscita
- 0,5 watt
- Raggio
- 1–2 km
- Applicazioni
- Piccole imprese
- Licenza
- Con licenza
- Modalità operativa
- Simplex / Duplex
- Banda di frequenza
- VHF / UHF
- Potenza di uscita
- Fino a 50 watt
- Raggio
- A livello cittadino
- Applicazioni
- Aziende medie e grandi
- Licenza
- Con licenza
- Modalità operativa
- Trunked
- Banda di frequenza
- VHF / UHF
- Potenza di uscita
- Fino a 50 watt
- Raggio
- Ampia area
- Applicazioni
- Grandi organizzazioni
Choosing the right tier
- Tier I — short-range communications, no network infrastructure, no license. Suited to simple and temporary deployments.
- Tier II — extended coverage on assigned frequencies, conventional infrastructure, data features and encryption. The right choice for most professional organizations.
- Tier III — trunking for high traffic volumes, dynamic channel allocation, scalable to thousands of users. For large mission-critical networks.
Frequently asked questions
Can DMR radios from different manufacturers communicate with each other?
Yes. Devices from different manufacturers can interoperate, provided they comply with the ETSI DMR standards.
What is TDMA and why does it matter in DMR?
TDMA (Time Division Multiple Access) divides a single frequency into two time slots, allowing two simultaneous calls on the same 12.5 kHz channel. This doubles capacity without requiring additional frequencies.
Do I need a license to use DMR Tier II and Tier III radios?
Yes. Both Tier II and Tier III operate on licensed frequencies. In Italy, the authorization is requested from the Ministry of Enterprises and Made in Italy (MIMIT).
Can I migrate from a Tier II system to a Tier III system?
Migration is possible but requires additional hardware and infrastructure for the trunking controller. Planning must account for current traffic volume and the scalability needed going forward.