@rockerest @Fallenstedt
You got it! The antenna picks up the RF from the aircraft and feeds it to the #SDR (30 dollar software defined radio ie, USB dongle) and then the #raspberrypi etc runs #dumpvdl and you get #JSON out.
The dumpvdl config contains the USB device number, the 4-6 or so frequencies to listen on etc.
Here is a nice short sample of the JSON direct from the decoder (ie, it has both name:value).

https://github.com/thebaldgeek/thebaldgeek.github.io/blob/main/json/dumpvdlJSON.json

Thanks again for sharing your thoughts!

Added two Aussie stations to the map while we were at it.
@scanSydney and @airman941 enter the rabbit hole that is #dumpvdl and #nodered #worldmap
Mostly just testing stuff. @AirframesIO is doing the real mapping.
Its more an 'excuse' for me to yell at #JSON and #JavaScript

Im on the fence about how much a non-coder like me should rant about coding stuff like #JSON.
I clearly don't understand it even after many years of trying to use it.
Long story short, this evening, I used some cut/paste #JavaScript to add labels and #dumpvdl data to #nodered

Here is last nights #dumpVDL #ACARS messages for the SoCal/Arizona area.
The air band antenna picks up the signal, usual #RTLSDR v 3 receives it, #RaspberryPi running #dumpvdl decodes it, MQTT sends the JSON, #nodered extracts the lat/lon and plots it on the map.

Night flight patterns are always quiet, as are weekends, going to let it run and see what we get.