The VHF Data Link mode 2 (VDL2) is a relatively new wireless transmission mode used on aircraft for sending short messages, position data (similar to ADS-B) and also for allowing traffic controllers to communicate to pilots via text and data. VDL2 is an evolution of ACARS and is eventually supposed to replace it entirely. The advantage over ACARS is that VDL2 can transmit data 10 times faster, and supports a much wider range of services. The main default channel is at 136.975 MHz, but channels could exist on other air band frequencies too.
Over on GitHub Tomasz Lemiech (szpajder – also the author of RTL-Airband) has uploaded a new VDL2 decoder called dumpvdl2. This is a lightweight command line Linux based VDL2 decoder and protocol analyzer. The features include:
- Runs under Linux (tested on: x86, x86-64, Raspberry Pi)
- Supports following SDR hardware:
- RTLSDR (via rtl-sdr library)
- Mirics SDR (via libmirisdr-4)
- reads prerecorded IQ data from file
- Decodes up to 8 VDL2 channels simultaneously
- Outputs messages to standard output or to a file (with optional daily or hourly file rotation)
- Outputs ACARS messages to PlanePlotter over UDP/IP socket
- Supports message filtering by type or direction (uplink, downlink)
- Outputs decoding statistics using Etsy StatsD protocol
In a previous post we showed how VDL2 could be decoded with MultiPSK on Windows. But the advantage of dumpvdl2 is that it allows you to set up a lightweight monitoring station on something like a Raspberry Pi. dumpvdl2 can also be interfaced with PlanePlotter, and statistics can be graphed with another program such as Grafana.