DMR — Digital Mobile Radio for Ham Radio
DMR (Digital Mobile Radio) is a digital voice standard originally developed for commercial land mobile radio that has been widely adopted by amateur radio operators. DMR replaces the analogue FM audio in a radio with TDMA (Time Division Multiple Access) digital encoding, providing clearer audio, more efficient spectrum use, and the ability to connect repeaters across the internet into worldwide talk group networks. DMR is the most widely deployed digital voice system in amateur radio globally, with thousands of repeaters and millions of contacts made daily.
TDMA and time slots
DMR uses TDMA — Time Division Multiple Access — to split a single 12.5 kHz channel into two time slots. Time Slot 1 (TS1) and Time Slot 2 (TS2) alternate 30 milliseconds at a time, so quickly that neither slot interferes with the other. This effectively doubles the capacity of a single repeater channel — two completely independent conversations can happen simultaneously on the same frequency. TS1 is typically used for wide-area and international traffic, while TS2 is reserved for local and regional talk groups, though this varies by repeater.
Talk groups and IDs
DMR uses a system of talk groups — numbered group addresses that allow conversations to be routed to specific groups of users. When you transmit on a talk group, all radios monitoring that talk group hear your transmission. Talk group 91 is the Worldwide English talk group on BrandMeister, meaning anyone on any connected repeater monitoring TG91 can hear you. More specific talk groups cover continents (TG302 for North America), countries (TG3100 for the US), states, and local groups.
Every DMR radio has a unique Radio ID — a number registered to your callsign at radioid.net. This ID is transmitted with every transmission and is how the network identifies you, routes your calls, and logs your contacts.
Register for a DMR ID
Go to radioid.net and register for a DMR Radio ID using your callsign. This is free and takes a day or two to process. Your DMR ID is a unique number (typically 7 digits for US operators) that must be programmed into your radio before you can use DMR networks. Without a registered ID, your transmissions may be rejected by networked repeaters.
Get a DMR-capable radio
Popular entry-level DMR radios include the TYT MD-UV380 and MD-380, Anytone AT-D878UV and AT-D578UV, Radioddity GD-77, and Baofeng DM-1801. The Anytone AT-D878UV is widely considered the best mid-range DMR radio for amateur use. Prices range from $50 for basic models to $200+ for feature-rich options. Make sure the radio supports the DMR Tier II standard used by amateur repeaters.
Create a codeplug
A codeplug is the programming file that configures your DMR radio — channels, talk groups, time slots, colour codes, zones, and scan lists. Creating a codeplug from scratch is complex. Most operators start with a community codeplug for their region — search for "[your state/region] DMR codeplug" to find pre-built files for your area. The Anytone CPS (Customer Programming Software) and open-source alternatives like OpenGD77 CPS are used to write codeplugs to your radio.
Find local DMR repeaters
Use RepeaterBook.com filtered to DMR mode to find DMR repeaters near you. Note the output frequency, offset, colour code (DMR's equivalent of CTCSS tone, typically CC1), and which network the repeater is connected to (BrandMeister, DMR-MARC, TGIF, etc.). Add these to your codeplug. Most areas have at least one BrandMeister-connected repeater.
Make your first DMR contact
Once your radio is programmed with a local repeater and talk groups, key up on TG91 (Worldwide English) or a local talk group and introduce yourself. DMR contacts follow normal voice operating procedures — give your callsign, name, and location just as you would on FM. Most DMR operators are friendly and helpful to new users.
| Network | Website | Scope | Notes |
|---|---|---|---|
| BrandMeister | brandmeister.network | Worldwide — largest network | Most repeaters, most users, most talk groups |
| DMR-MARC | dmr-marc.net | Worldwide | Original commercial-grade amateur DMR network |
| TGIF | tgif.network | Worldwide | Alternative network, some unique talk groups |
| FreeDMR | freedmr.uk | International | UK-based, connected to many regional networks |
What is a colour code in DMR?
A colour code (CC) is DMR's equivalent of a CTCSS tone — it identifies which repeater system you are accessing when multiple DMR signals may be present on the same frequency. Most amateur DMR repeaters use Colour Code 1 (CC1). Your radio must be programmed with the correct colour code for each repeater or it will not open the repeater, even if you are on the correct frequency.
What is the difference between BrandMeister and DMR-MARC?
Both are worldwide amateur DMR networks that connect repeaters via the internet. BrandMeister is the larger and more flexible of the two, with a web dashboard that allows users to manage their hotspot connections and monitor active talk groups in real time. DMR-MARC was the original large-scale amateur DMR network and has a more commercial-grade infrastructure. Many repeaters connect to both networks simultaneously.
Do I need a repeater to use DMR?
No — you can use a DMR hotspot, which is a low-power internet-connected device (typically a Raspberry Pi running Pi-Star or MMDVM software) that connects your radio directly to DMR networks via your home internet connection. Hotspots like the MMDVM Hotspot, ZumSpot, and SharkRF openSPOT allow you to access DMR networks from home or portable locations regardless of local repeater coverage.
Can my analogue FM radio work on DMR repeaters?
No — DMR and analogue FM are incompatible modes. However, many DMR repeaters have an analogue FM slot or a separate analogue input that bridges to DMR. Check RepeaterBook for whether a specific repeater supports analogue FM access. Some radios like the Anytone AT-D878UV support both DMR and analogue FM and can be programmed to use both on different channels.