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Install iridium-toolkit

iridium-toolkit is a set of tools developed by the Chaos Computer Club Munich for parsing and decoding Iridium satellite frames. It works in conjunction with a demodulator (either gr-iridium or iridium-sniffer) that captures the raw Iridium bursts from the air.

How the Iridium decoding pipeline works​

Decoding ACARS over Iridium requires two components:

  1. A demodulator that captures and demodulates Iridium satellite bursts:

    • iridium-sniffer (recommended) — Lightweight standalone C program. No GNU Radio dependency, runs well on Raspberry Pi.
    • gr-iridium — GNU Radio-based demodulator. More resource-intensive but well-established.

  2. iridium-toolkit that parses the demodulated frames and extracts ACARS messages.

Installation on Debian/Ubuntu​

Install dependencies​

sudo apt-get install build-essential python3 python3-pip git

Install iridium-toolkit​

git clone https://github.com/muccc/iridium-toolkit.git
cd iridium-toolkit
pip3 install -r requirements.txt
sudo apt-get install cmake libsoapysdr-dev soapysdr-module-rtlsdr
git clone https://github.com/alphafox02/iridium-sniffer.git
cd iridium-sniffer
mkdir build && cd build
cmake ..
make
sudo make install

iridium-sniffer supports: HackRF, BladeRF, USRP (UHD), and SoapySDR (including RTL-SDR).

Alternative: Install gr-iridium​

If you prefer the GNU Radio-based demodulator:

sudo apt-get install gnuradio gnuradio-dev
git clone https://github.com/muccc/gr-iridium.git
cd gr-iridium
mkdir build && cd build
cmake ..
make
sudo make install
sudo ldconfig

Usage​

Capture and decode​

The typical workflow pipes demodulated output from iridium-sniffer into iridium-toolkit:

iridium-sniffer -d driver=rtlsdr 2>/dev/null | python3 iridium-parser.py

Docker option​

A Docker container is available that bundles gr-iridium and iridium-toolkit together:

docker pull ghcr.io/jkrasuk/docker-gr-iridium-toolkit

See the docker-gr-iridium-toolkit repository for Docker Compose configuration.

Hardware requirements​

  • SDR: Any SDR that can tune to the Iridium L-Band (1616–1626.5 MHz). Higher bandwidth SDRs (like HackRF at 20 MHz) capture more of the Iridium band simultaneously and will decode more bursts. An RTL-SDR works but has limited bandwidth (~2.4 MHz).
  • Antenna: An omnidirectional L-Band antenna with clear sky visibility. A simple patch antenna or helical antenna works well.
  • LNA: A low-noise amplifier for the 1.6 GHz range is recommended (e.g., Nooelec SAWbird+ IR).
note

Iridium decoding is more advanced than VHF ACARS or VDL2 reception. If you're just getting started with Airframes, consider starting with acarsdec or dumpvdl2 first.