Mode DMR

DMR (Digital Mobile Radio), two-slot TDMA.

Group	Two-way radio
Default frequency	446.10625 MHz
Default sample rate	2.4 Msps
In the mode list	Digital voice

Step-by-step: Tutorial-DMR

What DMR is

DMR is a digital two-way radio standard (TDMA, 12.5 kHz) used by businesses, public services and amateurs.

Frequencies and settings

Digital two-way radio.

Setting	Value
Start frequency	446.10625 MHz
Tuning range of the mode table	30 to 1000 MHz
Sample rate asked	2.4 Msps
Lowest working rate	1 Msps
Channel width	12.5 kHz

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is Digital voice.

What OnAir shows

Talkgroups, IDs and data (no voice).

Tips and caveats

• Checked with generated signals and impairments; recordings of real signals welcome. Voice through the vocoder is unverified on real recordings.
• Voice needs mbelib, which is not included in OnAir (see below).
• Which radio: Usually yes for narrowband signals: an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: In many countries it is illegal to intercept or disclose private radio communications. OnAir is a receiver: encrypted calls show up only as encrypted and are never decrypted, and voice needs a library you install yourself. Follow the law where you live. See Legal.

Voice needs mbelib (not included)

mbelib is not included in OnAir and must be installed by you. The AMBE / IMBE vocoders are patented in some countries; check your local law first. Calls, IDs and data are shown without it; the voice stays silent until you:

1. Build mbelib from github.com/lwvmobile/mbelib as a shared library (Linux: sudo apt install git cmake build-essential, git clone https://github.com/lwvmobile/mbelib, then mkdir build && cd build && cmake .. && make && sudo make install && sudo ldconfig; macOS: brew install cmake git and the same; Windows: MSYS2 with -DBUILD_SHARED_LIBS=ON).
2. Copy it into the OnAir codecs folder (libmbe.dylib, libmbe.so or libmbe.dll). The ? next to the sound has an Open codecs folder button.
3. Press Look again (no restart needed).

Steps for every system are on the Voice codecs page. OnAir never decrypts: encrypted calls show up only as encrypted.

Related pages

• Digital voice: DMR, D-STAR, P25
• Voice codecs
• All modes, Two-way radio
• Supported radios, Troubleshooting, FAQ
• More in Two-way radio: NXDN, P25, dPMR / PMR446, TETRA, TETRAPOL