Knowledge base · DMR

DMRhub Knowledge base

Practical step-by-step guides for the radio amateur, organised by section. Firmware, hotspots, antennas, repair, power and accessories — things we've worked through on the air ourselves. Currently 112 articles in 10 sections.

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Basics

Where to start: how DMR works, the digital modes, frequencies and the law.

35 guides →
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Firmware

Free and factory radio firmware: OpenGD77, md380tools.

9 guides →
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Codeplug

Setting up radios through the CPS: zones, talkgroups, RX groups, contacts.

11 guides →
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Hotspots

Building, configuring and connecting an MMDVM hotspot to the network.

24 guides →
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Calibration

When the radio «can't hear»: tuning the modem frequency by BER.

7 guides →
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Antennas

DIY antennas and measurements: whip, collinear, balcony, SWR.

8 guides →
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Repair

Fixing radios: connectors, buttons, displays, bricks — by model.

6 guides →
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Modifications

Useful tweaks: band, GPS, Bluetooth, cooling, audio.

3 guides →
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Power

Batteries and power: capacity, safety, the hotspot PSU.

4 guides →
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Accessories

Cables, drivers, headsets and speaker mics for radios.

5 guides →

Frequently asked questions

What is DMR in simple terms?
DMR (Digital Mobile Radio) is an open digital radio standard. Voice is encoded by a vocoder and sent as data: clean audio, two voice channels (time slots) on one frequency, and text messages.
What is a hotspot and why do you need one?
A hotspot is a small transceiver (usually a Raspberry Pi with an MMDVM modem) that links your radio to the DMR network over the internet. You need it where there's no repeater nearby: the radio reaches the wider network through your home internet.
Do you need a licence to operate DMR in Russia?
To transmit on the amateur bands (2 m 144–146 MHz, 70 cm 430–440 MHz) you need a callsign and a licence. Without a licence, only receiving and the licence-free LPD (433 MHz) and PMR (446 MHz) bands are legal.
What are a talkgroup and a time slot?
A talkgroup is a numbered group «channel» that your voice goes to. A time slot (TS1 or TS2) is one of DMR's two time channels on a single frequency; on a simplex hotspot you work on TS2.
What is Color Code in DMR?
Color Code (0–15) is a «digital subtone»: it must match between the radio and the hotspot/repeater, otherwise the radio won't open up. It's effectively the equivalent of a CTCSS tone in analogue.
Which radio should a beginner choose for DMR?
A cheap Baofeng DM-1801 or Radioddity GD-77 (which can be flashed with OpenGD77) is a fine start; for the demanding, a TYT MD-UV380 or AnyTone D878UV. The main thing is the right band (usually 70 cm) and DMR support.
How do you get a DMR ID?
A global DMR ID is issued free by RadioID.net against a verified callsign. Inside the DMRhub network a private ID is issued automatically on registration, and each hotspot needs its own identifier.
How is DMRhub different from public DMR networks?
DMRhub is a private network with its own master server: its own talkgroups, private IDs, access control and independence from someone else's infrastructure, without the noise of public reflectors.
This section is updated regularly Got a question or spotted an error — message us on our Telegram.