DMR radio: what Digital Mobile Radio is and how it is set up

DMR radio: Digital Mobile Radio in plain words

DMR stands for Digital Mobile Radio. It is a standard written by ETSI, the European standards body, and first ratified in 2005.1 Any maker can build to it, and the DMR Association counts a wide range of vendors behind it.2

A DMR radio turns your voice into data before it sends it. The data goes out in short bursts. Each 12.5 kHz channel is cut into two time slots of 30 ms, numbered 1 and 2, and the pattern repeats every 60 ms.3

This method is called TDMA, time division multiple access: two users take turns on one frequency so fast that both hear a steady call. The signal itself carries 4,800 symbols per second, with 2 bits in each symbol.3 That makes 9,600 bits per second on one channel.

The standard has a promise built in. A radio that follows it must work over the air with radios from other makers.3 How DMR compares with plain FM radio is covered in DMR vs analog radio.

Pick two types below to see how license-free DMR446 differs from licensed DMR.

DMR tiers: Tier I, Tier II and Tier III

The ETSI standard defines three tiers, or levels, of DMR products.3 Each tier is a different way to run a radio system.

"Conventional" means each group has its own fixed channel, like a channel knob on any walkie-talkie. "Trunked" means the system picks a channel for every call, so many groups share a few frequencies.

The tiers do not mix. ETSI says the three tiers work independently and there is no interoperability across them.3 One radio can still support two tiers: the Motorola R7 lists both Tier II and Tier III.5

DMR446: license-free DMR on PMR446 channels

DMR446 is Tier I DMR on the European PMR446 band, 446.0 to 446.2 MHz. The CEPT decision for the band names the DMR standard for digital radios with 12.5 kHz channels.4

The rules are the same as for every PMR446 radio. The radio is a hand-held with a built-in antenna, at no more than 500 mW. Base stations, repeaters and fixed set-ups are not allowed.4

Since 1 January 2018, the digital channel plan covers the whole band, with the first 12.5 kHz carrier at 446.00625 MHz.4 The full channel list is on the PMR446 frequencies page.

The Hytera BD505LF is one DMR446 radio. Hytera sells it as a license-free DMR radio with 0.5 W, 16 channels, and both analog FM and digital modes.6

dPMR446 is a different digital standard on the same band. It uses 6.25 kHz channels, one call per channel, and works radio to radio only.74 A DMR446 radio and a dPMR446 radio share the band, not the language.

In the US, DMR radios run on licensed channels, such as those of the FCC's Industrial/Business Pool. Companies, schools, clinics and clergy groups can hold that license.8 More in do you need a license for a walkie-talkie.

DMR radio settings: the four that both radios must share

On an analog radio, two people need the same channel and the same privacy code. A DMR radio needs the same frequency plus four digital settings.

The color code is not an address. ETSI says plainly that it is not used to call a person or a group.3 It works more like a site name that keeps two nearby systems apart.

A talkgroup is the group you belong to. Motorola's CP100d guide says a radio must be set up as part of a group to make or receive that group's calls.9 A private call goes from one radio to one other radio.9

These settings live in the radio's programming file. Motorola's guide sends users to their dealer for it.9 The maker's software and a cable set channels, color codes, slots, talkgroups and contacts in one go.

Here is how a small warehouse with one repeater could set up its radios:

Two teams talk at the same time on one licensed frequency, each in its own slot. The "All call" channel reaches every radio that lists that talkgroup.

DMR encryption and data

Encryption is an option on top of the standard. The ETSI air-interface document leaves security out of its scope.3 The DMR Association lists four encryption types: ARC4 (40-bit), DES (64-bit), AES-128 and AES-256, for both voice and data.2

Both radios need the same type and the same key to hear each other. The Kenwood NX-1300 lists ARC4.10 The Motorola R7 lists AES-256.5

DMR also carries data. The DMR Association names text messages, GPS location and telemetry as add-ons, and the second slot can carry data next to a voice call.2

DMR brands and compatibility

DMR is an open standard. The DMR Association calls it fully public, backed by a wide range of vendors.2

Its working group keeps lists of mandatory and optional features for Tier II and Tier III. Two makers at a time test their radios against them.11 Each certificate names the features tested, for one hardware model and one software release.11

Basic calls work across brands, since every radio must work over the air with other makers' radios.3 Makers then add their own system features on top:

Capacity Plus is Motorola's single-site trunking for up to 1,000 users. Capacity Max is Motorola's Tier III system.13 Hytera's XPT shares channels across up to 16 sites, with up to 8 voice repeaters per site.12

The repeaters in these systems come from the maker. Hytera's IP Connect, for example, runs on Hytera Tier II repeaters with an IP Connect license.14 Hytera adds that DMR radios of any brand work on it.14 Ask for the maker's list before you mix radios on a trunked system.

The repeater and linking side is explained in repeaters and IP Site Connect.

DMR radios: hand-helds by maker

These DMR hand-helds are in our database. All of them follow the ETSI DMR standard, and each maker lists its own extras.

The next table adds power, the maker's battery claim, water rating and price.

The BD505LF is the only license-free radio here; the rest need a business license. Full reviews cover the Motorola R7 and the Hytera PD405 in detail.

DMR mobile radios and base stations

A DMR mobile radio goes in a vehicle and runs on its power. Hytera's HM785 sends up to 50 W on VHF and 45 W on UHF and holds 1,024 channels.18 The same mobile can also sit in a control room.18

A base station is a fixed radio at one site. In Tier II, radios talk directly or through a base station that repeats the call.3

DMR for ham radio operators

Amateur radio operators use DMR too, on ham bands, under an amateur license.19 BrandMeister, an amateur DMR network, links repeaters and hotspots over the internet so any talkgroup is reachable from any of them.20

A hotspot is a small personal box that links a DMR radio to such a network. Calls on these networks are organized by talkgroups, as on a business system.20

Questions

Sources

1. The DMR standards, developed by ETSI · DMR Association
2. Key benefits of DMR technology · DMR Association
3. ETSI TS 102 361-1 V2.7.1 (2026-05): DMR air interface protocol · ETSI
4. ECC/DEC/(15)05: analogue and digital PMR 446, 446.0-446.2 MHz, amended 2 March 2018 · CEPT ECC
5. MOTOTRBO R7 data sheet (EMEA) · Motorola Solutions
6. BD505LF licence-free DMR handheld radio · Hytera
7. ETSI TS 102 490 V1.8.1 (2014-06): peer-to-peer digital PMR, FDMA, 6.25 kHz, up to 500 mW · ETSI
8. 47 CFR 90.35: Industrial/Business Pool · eCFR
9. MOTOTRBO CP100d full keypad portable radio user guide (2021) · Motorola Solutions
10. NX-1000 series portable radios specification sheet · Kenwood