Install and Configure acarsdec
acarsdec is a multi-channel VHF ACARS decoder. This guide covers installation, configuration, and feeding to Airframes.
Installation on Debian/Ubuntu
Install dependencies
sudo apt-get install build-essential cmake git libusb-1.0-0-dev librtlsdr-dev libxml2-dev zlib1g-dev pkg-config
Install libacars (required for message decoding)
git clone https://github.com/szpajder/libacars.git
cd libacars
mkdir build && cd build
cmake ../
make
sudo make install
sudo ldconfig
Build acarsdec
git clone https://github.com/f00b4r0/acarsdec.git
cd acarsdec
mkdir build && cd build
cmake ..
make
sudo make install
Configuration
Basic usage
acarsdec --output json:udp:host=feed.acars.io,port=5550 -i MY-STATION-ACARS --rtlsdr 0 130.025 130.450 131.125 131.550
Key command-line options
| Option | Description |
|---|---|
--rtlsdr <device> f1 f2 ... | RTL-SDR device number followed by frequencies (MHz) |
--airspy <device> f1 f2 ... | Airspy device number followed by frequencies |
--output <format> | Output format: see --output help for details |
-i <station_id> | Station identifier included in output messages |
-g <gain> | Tuner gain in dB (leave unset for AGC - not recommended) |
-p <ppm> | Frequency correction in PPM |
-A | Only display aircraft (downlink) messages, not uplink |
-e | Exclude empty messages |
Feeding to Airframes
To feed VHF ACARS data to Airframes, use the --output json:udp:host= format:
acarsdec --output json:udp:host=feed.acars.io,port=5550 -i MY-STATION-ACARS -g 42 --rtlsdr 0 130.025 130.450 131.125 131.550
Important parameters for feeding:
--output json:udp:host=feed.acars.io,port=5550enables JSON output (required for Airframes) and sends data to the Airframes ACARS ingest (UDP port 5550)-i MY-STATION-ACARSidentifies your station (see Station ID format below)
Station ID format
Your station ID helps identify your feed on Airframes. The recommended format is:
XX-YYYY-ACARS
Where:
XX— Your initials or a personal identifier (e.g.,KE)YYYY— The ICAO code of the nearest airport (e.g.,KSEA)ACARS— The decoder type
Example: KE-KSEA-ACARS
Common ACARS Frequencies
All frequencies must be within the same 2 MHz band. Up to 8 channels can be decoded simultaneously.
North America
| Frequency | Provider |
|---|---|
| 129.125 MHz | ARINC (USA/Canada) |
| 130.025 MHz | ARINC (USA/Canada) |
| 130.425 MHz | ARINC (USA) |
| 130.450 MHz | ARINC (USA/Canada) |
| 131.125 MHz | ARINC (USA) |
| 131.550 MHz | ARINC (USA/Canada) |
Recommended North America set: 130.025 130.425 130.450 131.125 131.550
Europe
| Frequency | Provider |
|---|---|
| 131.525 MHz | SITA |
| 131.725 MHz | SITA (primary) |
| 131.825 MHz | SITA |
| 131.850 MHz | SITA |
| 136.900 MHz | SITA |
| 136.925 MHz | ARINC |
Recommended Europe set: 131.525 131.725 131.825 131.850
Asia-Pacific
| Frequency | Provider |
|---|---|
| 131.550 MHz | SITA (primary) |
| 131.450 MHz | SITA |
| 129.125 MHz | ARINC |
| 130.025 MHz | ARINC |
Middle East / Africa
| Frequency | Provider |
|---|---|
| 131.550 MHz | SITA (primary) |
| 129.125 MHz | ARINC |
| 130.025 MHz | ARINC |
Check the Airframes stations page to see what frequencies other feeders in your area are using. Frequencies vary by region and may change — the station list shows what's working for feeders near you.
Running as a Service
To run acarsdec at boot, create a systemd service:
sudo tee /etc/systemd/system/acarsdec.service << 'EOF'
[Unit]
Description=acarsdec ACARS decoder
After=network.target
[Service]
Type=simple
ExecStart=/usr/local/bin/acarsdec --output json:udp:host=feed.acars.io,port=5550 -i MY-STATION-ACARS -g 42 --rtlsdr 0 130.025 130.450 131.125 131.550
Restart=always
RestartSec=5
[Install]
WantedBy=multi-user.target
EOF
sudo systemctl daemon-reload
sudo systemctl enable acarsdec
sudo systemctl start acarsdec
Verifying Your Feed
Once running, visit the Airframes stations page and search for your station ID. You should see message counts appearing within a few minutes (depending on air traffic in your area).
Troubleshooting
No messages received:
- Verify your SDR is detected:
rtl_test - Check your gain setting — try different values between 20–48
- Ensure you're using frequencies active in your region
- Make sure no other software is using the SDR device
Permission errors:
- Create a udev rule for the RTL-SDR:
sudo sh -c 'echo "SUBSYSTEM==\"usb\", ATTRS{idVendor}==\"0bda\", ATTRS{idProduct}==\"2838\", MODE=\"0666\"" > /etc/udev/rules.d/rtl-sdr.rules' - Blacklist the kernel DVB-T driver:
sudo sh -c 'echo "blacklist dvb_usb_rtl28xxu" > /etc/modprobe.d/blacklist-rtlsdr.conf' - Reboot after making these changes