Installation · RTL-SDR v4 · TETRA Decoder · Setup

Installation & TETRA decoder projects

RTL-SDR v4 driver installation (Zadig/WinUSB), setting up SDR++, cropinghigh sdrpp-tetra-demodulator step by step, SDR-Trunk, Telive-2, GopherTrunk — all tools compared.

⚠ Legal notice The software described here can technically decode TETRA signals. Applying it to the German emergency-services digital radio (380–400 MHz) is, under TKG §148, a criminal offence. This guide is for technical education, your own systems and legal use cases.

RTL-SDR v4 — driver installation (Windows)

RTL-SDR v4 not yet NOT plugged in

Zadig download: zadig.akeo.ie

Plug in the RTL-SDR v4 via USB

Zadig as Administrator launch → Options → List All Devices

Select the device: Bulk-In, Interface (Interface 0) or RTL2838UHIDIR

Target driver: WinUSB select (NOT libusbK)

Click "Install Driver" → wait until Driver Installation: SUCCESS

RTL-SDR v4 note: If Zadig shows two entries (Interface 0 and Interface 1), only switch Interface 0 to WinUSB. Interface 1 is for GPIO functions.

RTL-SDR blacklist (Linux)

# blacklist the kernel driver (prevents conflict with librtlsdr):
echo 'blacklist dvb_usb_rtl28xxu' | sudo tee /etc/modprobe.d/blacklist-rtl.conf
echo 'blacklist rtl2832' | sudo tee -a /etc/modprobe.d/blacklist-rtl.conf
sudo modprobe -r dvb_usb_rtl28xxu 2>/dev/null || true

# test whether the RTL-SDR is detected:
rtl_test -t
# expected output: "Found 1 device(s)"

Install SDR++ (Linux)

# Ubuntu 22.04 / Debian 12:
sudo apt install librtlsdr-dev libfftw3-dev

# prebuilt .deb from GitHub Releases:
wget https://github.com/AlexandreRouma/SDRPlusPlus/releases/latest/download/sdrpp_ubuntu_jammy_amd64.deb
sudo dpkg -i sdrpp_ubuntu_jammy_amd64.deb
sudo apt install -f

# start:
sdrpp

TETRA decoders — which tool for which purpose?

Project	Difficulty	Platform	Strength	Weakness
GopherTrunk	Very easy	Win/Linux/macOS/Pi	One binary, no dependencies	Browser console in development
OpenEar	Easy	Win/Linux	TETRA/DMR/P25 in one GUI	Less TETRA depth
cropinghigh sdrpp-tetra	Medium-high	Linux (WSL)	Cleanest DSP signal chain	Compiling, Linux-native only
SDR-Trunk	Fair	Win/Linux/macOS	Multi-protocol, GUI, multiple dongles	TETRA experimental, needs Java
Telive / Telive-2	High	Linux	Dedicated TETRA, proven	Complex installation, needs GNU Radio

GopherTrunk — the quickest start

# Linux/macOS — a single binary, no dependencies:
chmod +x gophertrunk
./gophertrunk --device rtlsdr --frequency 385000000

# Windows:
gophertrunk.exe --device rtlsdr --frequency 385000000

# browser console: http://localhost:8080
# supported protocols: P25 Phase 1+2, DMR, TETRA, NXDN,
# Motorola Type II, EDACS, LTR, MPT1327, dPMR, D-STAR, YSF

cropinghigh sdrpp-tetra-demodulator (Linux)

The technically cleanest plugin for SDR++. It implements the full DSP signal chain: AGC → FLL → RRC filter → timing recovery → Costas loop → symbols → differential decoder → osmo-tetra.

Dependencies: sudo apt install build-essential cmake libvolk2-dev libtalloc-dev pkg-config

Install SDR++ (see above)

Clone the repository: git clone https://github.com/cropinghigh/sdrpp-tetra-demodulator.git

Patch the ETSI codec: cd src/decoder/etsi_codec-patches && chmod +x download_and_patch.sh && ./download_and_patch.sh

Compile: cd ../../.. && mkdir build && cd build && cmake .. && make -j$(nproc) && sudo make install

In SDR++: Module Manager → tetra_demodulator → + → give it a name → the plugin appears in the panel

Drag the VFO to the centre of the signal → watch the constellation diagram → 4 clear dots = synchronisation

Interpreting the constellation diagram

Appearance	Meaning	Action
4 clearly separated dots	Perfect synchronisation	None — keep watching
4 dots slightly widened	Slight noise	Increase gain slightly
4 dots rotating	Frequency offset, FLL not yet settled	Wait 5–10 seconds
Diffuse cloud	Signal too weak (<20 dB SNR)	Improve the antenna
Only 2 dots	No TETRA on this frequency	Look for another frequency

SDR-Trunk

📺 SDR-Trunk + RTL-SDR on Windows 11 — January 2026, current
(Java, multi-protocol)

# install Java 21+: adoptium.net
# download the SDR-Trunk release: github.com/DSheirer/sdrtrunk/releases
# Windows: run bin\sdr-trunk.bat
# Linux: run bin/sdr-trunk.sh

# for TETRA: Playlist Editor → Create System → Protocol: TETRA
# enter the control-channel frequency manually
# 2x RTL-SDR v4 recommended (control + voice channel)

Complete checklist: RTL-SDR v4 + antenna → Zadig/blacklist → test SDR++ (FM radio) → the TETRA tool you want (table above) → legal test frequency or your own system → observe the legal limits

Next: amateur radio licence →