Radio technologies
DMR technology: professional digital radio for businesses and infrastructure.
DMR, short for Digital Mobile Radio, is the European standard for professional digital radio: a 12.5 kHz channel carries two communications, with voice, data, and GPS location over the same network. This guide explains the three Tiers, how a DMR network works, what simulcast is, and what Teleproject builds: from network design to dispatching.
What is DMR
DMR, short for Digital Mobile Radio, is the ETSI standard (ETSI is the European telecommunications standards body) for professional digital radio communications. It was created to bring digital to business radio networks: clean audio right up to the edge of coverage, text messages and GPS location, and safety functions for people working in the field, such as man-down and emergency calling.
The defining technical feature of DMR is the 12.5 kHz channel split into 2 TDMA slots: the same frequency carries two independent communications. For the same license, a DMR network doubles the capacity of an analog network. It is today the most widely used professional digital radio standard in the world, from business fleets to infrastructure networks.
Teleproject designs and builds complete mission-critical radio networks in DMR technology, from licensing to commissioning: business networks for utilities and industry and simulcast networks along highway routes.
The three DMR Tiers
The standard defines three levels, from the simplest to the most structured. The choice depends on the fleet, the area, and the frequencies available.
Tier I
License-free
PMR446 radios: a harmonized license-free band, limited power, an integrated antenna, and no repeater. They are fine for personal use and small businesses.
Tier II
Licensed conventional
Assigned frequencies and repeaters: this is the DMR of business and infrastructure fleets, and the basis of most of the networks we build.
Tier III
Trunked
The network assigns channels dynamically to whoever needs to talk, with call queuing and priority. It is the configuration for large fleets and multi-site networks.
The channels, power levels, and usage rules of the three levels are explained in the dedicated article: Understanding the tiers of the DMR standard.
How a DMR network works
Four concepts are enough to understand any DMR project: the 2 TDMA slots, the difference between a conventional and a trunked network, simulcast, and migration from analog.
2 TDMA slots on a 12.5 kHz channel
Each DMR channel occupies 12.5 kHz and is divided in time into 2 alternating slots (TDMA): two independent communications travel over the same frequency, two conversations or voice on one slot and data on the other. Where an analog channel carries a single conversation, a DMR channel carries two.
Conventional or trunked network
In a conventional Tier II network, each group works on the channels set in programming: simple and robust, ideal for small and medium fleets. In a trunked Tier III network, the channels become a shared pool: the network assigns a free channel to whoever presses the PTT and releases it when the conversation ends, with call queuing and priority.
Multi-site simulcast (same-frequency) coverage
To cover a long route, a highway, a valley, or a transport line, the most efficient solution is the simulcast (same-frequency) network: multiple sites transmit in sync on the same frequency and their coverage areas merge into a single continuous cell. The radio never changes channel along the route, and a single pair of frequencies covers the entire route. It is the typical architecture of highway radio networks, a Teleproject specialty.
- Same frequency f1
- All the sites transmit on the same frequency, at the same instant: a single pair of frequencies covers the entire route.
- Continuous coverage
- The sites’ coverage areas overlap and merge: the radio does not change channel along the route.
- Synchronization
- A shared time and frequency reference (typically GPS) aligns the sites’ transmissions in the overlap zones.
Coverage is not improvised: it is designed with a radio coverage study and verified in the field with RF measurements and drive tests. Why simulcast makes sense is explained in the article Why switch to a DMR simulcast solution.
Migration from analog
DMR radios and repeaters also work in analog: the same fleet can use the existing analog channels and the new digital ones. Migration happens in stages, first the equipment and then the channels, without stopping service. The full path is in the article Moving from analog PMR networks to digital DMR.
The complete architecture
These elements make up the network: the terminals communicate with the repeaters and base stations, the sites connect to each other over an IP network with microwave radio links or optical fiber, and operators in the control room manage communications from the dispatch consoles.
- Terminals
- Portable and vehicle radios: they are the users’ access points to the network, in digital or analog (dual mode).
- Repeaters and base stations
- A single repeater covers one site; multiple coordinated sites cover large areas, in a multi-site or simulcast configuration. In Tier III the network controller assigns the channels.
- Links between sites
- The sites connect to each other and to the control room over an IP network, with microwave radio links or optical fiber.
- Control room
- The dispatch consoles manage the communications of the whole network, including alongside TETRA and analog networks.
Want to dig deeper into the standard, the functions, and the design criteria? Read the dedicated article: DMR radios: professional digital radio communication systems.
DMR or TETRA: which to choose
Both are ETSI standards for professional digital radio, with different network profiles.
Choose DMR when the fleet is small or medium and the budget is limited: a conventional Tier II or trunked Tier III network covers most business and infrastructure needs, and simulcast extends coverage over long routes. Choose TETRA when the fleet is large and the priority and encryption requirements are high: this is the typical case for public safety.
This is not a matter of principle: Teleproject designs both technologies, including mixed networks where the two coexist. You will find the comparison table in the guide to TETRA technology and the full comparison in the article DMR and TETRA: which standard to choose.
Where DMR is used
DMR is the radio technology of businesses and infrastructure: operational fleets, industrial sites, and routes to be covered without interruption.
Utilities and industry
Radio networks for energy and water utilities and for industrial sites, with lone-worker safety functions.
Highways and tunnels
Simulcast networks along the route and coverage in the tunnel bores, with continuous carrier monitoring.
Transport and logistics
Fleet communications for depots, terminals, and vehicles moving across large areas.
Public safety
Radio networks for local police, civil protection, and emergency services across the territory.
Mines and quarries
Reliable communications underground and at extraction sites, including hazardous environments.
Three use cases worth exploring: radios in ski resorts, protecting lone workers, and DMR and TETRA radios in ATEX environments.
What Teleproject offers for DMR
A DMR network is not an off-the-shelf product: it is a project. We handle the entire cycle, from licensing to maintenance, with products developed in-house for monitoring.
Complete, turnkey DMR networks
We handle the project with a single point of contact: coverage study, licensing, equipment supply, installation, commissioning, and maintenance under SLA contracts. Including the multi-site simulcast (same-frequency) networks along highway routes.
Portable and vehicle terminals
We supply, program, and integrate portable and vehicle DMR radios from Motorola Solutions (MOTOTRBO), Hytera, and Kenwood, with ATEX variants for explosion-risk environments.
Repeaters and base stations
The equipment to build and extend the network, from a single Tier II repeater to a simulcast network: the Radiodata (BS2500) and Radio Activity (Kairos) base stations and the MOTOTRBO, Hytera, and Kenwood repeaters.
Monitoring the DMR network
Track-TP supervises network equipment and sites over SNMP, with real-time alarms. TP-RFX monitors the presence of DMR carriers in the tunnel 24 hours a day and alerts technicians at the first missing signal.
DMR coverage in tunnels
DAS and radiating cable carry the DMR signal inside the tunnel bores. We have installed radio coverage systems in over 100 tunnels, across more than 500 km of highway routes, and we keep them under control with our monitoring products.
Dispatching and control rooms
Respondr unifies DMR, TETRA, and analog networks and cellular PTT in a single operator console. We also supply the Funktronic operator consoles and radio gateways, for which Teleproject is the exclusive distributor for Italy.
Browse the DMR catalog
The current models from the manufacturers we work with, with specifications and official datasheets: choose a category.
Portable terminals
The handheld DMR radios from Motorola Solutions, Hytera, and Kenwood, with ATEX variants.
Vehicle terminals
The in-vehicle radios for service vehicles and operational fleets.
Repeaters and base stations
The equipment to build the network, from the repeater to simulcast.
Operator consoles
The Funktronic operator consoles and radio gateways for dispatching.
Frequently asked questions about DMR
Frequencies, licensing, tiers, and range: the essential answers to the questions we hear most often.
What frequencies does DMR use?
DMR does not have a band of its own: it uses the ordinary licensed PMR bands, typically VHF 136–174 MHz and UHF 400–470 MHz. Each channel occupies 12.5 kHz and carries two communications thanks to the 2 TDMA slots. Tier I, by contrast, uses the PMR446 band, harmonized across Europe and license-free.
In Italy. DMR networks use the frequencies that the national frequency allocation plan (D.M. 31 agosto 2022) reserves for the professional mobile radio service, with the corresponding usage rights.
Do you need a license to operate DMR radios?
It depends on the Tier. PMR446 radios (Tier I) are license-free throughout Europe. Tier II and Tier III networks use frequencies subject to authorization from the national regulator, in every European country.
In Italy. A general authorization with frequency usage rights is required under D.Lgs. 259/2003; the application is submitted through the MIMIT portal and involves administrative fees and annual contributions. Teleproject handles the paperwork on the client’s behalf.
Is PMR446 DMR?
In part. Digital PMR446 radios use the DMR Tier I protocol: the 446 MHz band, license-free, power limited to 500 mW, an integrated antenna, and no repeater. They are fine for personal use and small businesses, but they do not replace a professional radio network.
What is the difference between DMR Tier II and Tier III?
Tier II is conventional DMR: each group works on the channels set in programming, with one or more repeaters. Tier III is trunked: the network assigns a free channel to whoever presses the PTT, with call queuing and priority. Tier II covers small and medium fleets; Tier III is worthwhile with large fleets and multiple sites.
Are DMR radios compatible with analog radios?
Yes. DMR radios and repeaters also work in analog and can switch between the two modes. Migration happens in stages, first the equipment and then the digital channels, without stopping service.
What is the range of a DMR radio?
There is no single number: range depends on the band, power, antenna, and terrain. Radio to radio, the range is a few kilometers; with a repeater it covers a city or a valley; with multi-site and simulcast networks, coverage extends as far as needed. This is why every network starts with a coverage study.
Let’s talk about your DMR project.
A new network, migration from analog, or a simulcast network along the route: we take care of design, build, and technical support, with a single point of contact.