This article explains what acarsdeco2 is, how it differs from other decoders, and how to set it up to turn your $20 RTL-SDR dongle into a real-time aircraft messaging receiver. acarsdeco2 is a lightweight, multi-channel ACARS decoder written in C. It is specifically designed to work with RTL-SDR devices (using the rtl-sdr library) and can decode multiple ACARS frequencies simultaneously within the bandwidth of your SDR.
If you’ve ever wanted to listen in on the digital conversations between airliners and ground stations, you’ve likely encountered the term ACARS . While many enthusiasts start with the well-known dumpvdl2 or acarsdec , a powerful and efficient alternative exists: acarsdeco2 .
acarsdeco2 --device 0 --freq-list 131.125e6,131.475e6,131.550e6,131.725e6,131.850e6 To feed decoded messages into a web dashboard or logging system: acarsdeco2
[2025-03-15 14:23:10] 131.550MHz: ACARS mode: 2 Reg: B-1234 Flight: CA1234 Message: .CA1234 001A YYZ ZBAA OOOI OUT 1423 You can also log raw text to a file:
acarsdeco2 --device 0 --freq-list 131.550e6 --json --http-port 8080 Then point a browser to http://localhost:8080/data for live JSON. A typical decoded message looks like this: This article explains what acarsdeco2 is, how it
acarsdeco2 --device 0 --freq-list 131.550e6 --output-file acars.log | Feature | acarsdeco2 | acarsdec | dumpvdl2 | |---------|------------|----------|----------| | Target | VHF ACARS | VHF ACARS | VDL Mode 2 (VHF) | | Multi-channel | Yes (up to 8) | No (run multiple instances) | Yes | | RTL-SDR | Native | Native | Native | | JSON output | Yes | Yes (with patch) | Yes | | Bit error correction | Good | Basic | Excellent | | VDL2 support | No | No | Yes | Note: dumpvdl2 decodes the newer VDL Mode 2 protocol (used alongside ACARS), while acarsdeco2 focuses on legacy ACARS. Advanced Tips 1. Reduce CPU usage acarsdeco2 --device 0 --freq-list ... --sample-rate 1.2e6 --corr-threshold 100 2. Forward to an aggregator Many users send data to ACARS Hub or ADS-B Exchange :
acarsdeco2 --device 0 --freq 131.550e6 This decodes only one frequency. To take advantage of multi-channel decoding: If you’ve ever wanted to listen in on
docker run --rm -it --device /dev/bus/usb --pull always ghcr.io/sdr-enthusiasts/docker-acarsdec:acarsdeco2 Here’s a minimal command to start decoding: