FlightAware Discussions

Newbie here

I just discovered this stuff as I was looking into software-defined radio to be able to listen in on the world as it deals with covid. The orange FA dongle and antenna set was cheap and I had a few RPis laying around so went for it.

I’m really blown away and have a better antenna and feedline coming. Might upgrade the receiver too as I learn more about this.

I keep my Pi’s locked down so the live data link didn’t work until I opened port 8080 but that really put me over the top! It’s just so surprising and amazing to me I can watch planes taxi around at my local airport, watch life flights from my local hospitals, etc. I had no idea this technology was so developed or easy to experiment with. It’s just nuts!

One thing I noticed and will be fixing with the new antenna is right now I have my antenna looking out a window right at the house next door. The view should be obstructed hard to the east but the polar plot shows a pretty good circle. The homes here are stucco with metal mesh underneath to support the stucco. I think I’ve got a big reflector. The houses are closely spaced and relatively tall compared to where the antenna is in the window so I think the signals bounce back and forth until they reach the antenna.

I suspect but don’t know that this might have affected my MLAT position. I set it very accurately manually, even to where on the lot my antenna is, but the live data map shows my location about a block away.

I know MLAT synchronizes between multiple receivers but does anyone know if it further refines your position based on those other receivers? I was surprised when I saw that offset and that’s the only way I can rationalize it. Or maybe positioning on the map allows a more precise location than it actually uses and the new dot/location is simply my location with a few fewer significant digits?

Anyway, very much enjoying this new hobby. It’s really interesting stuff!

There is a setting for dump1090-fa that fudges the accuracy of the receiver location on the map so you can have the map publicly available without revealing your exact position. You can adjust it to show your exact location if you want however:

Look for JSON_OPTIONS="--json-location-accuracy 1
in /etc/default/dump1090-fa

and change 1 to 2 for exact display.

The position you enter is the one used for mlat calculations and doesn’t change.

Thanks so much for that, caius! That’s the most favorable explanation!

I think I’ll leave it just the way it is. Should have, but didn’t, consider that. I have seen other station locations on a station map but that map wouldn’t let me zoom in enough to really see where stations were. Since the live data from the Pi is only local to my network I had just assumed it was showing me where FlightAware thought I was so I was concerned it might mess up MLAT positions.

Very good to know!