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Comment by tamimio | Hacker News Reader

A project I did a couple years ago was to have an onboard SDR that communicates automatically with airplanes in the vicinity, or switching to manual where the drone operator can communicate as if they are “on-board” through the internet by a mic on ground. I can see something like this is doable, with a modified system to fit the length flight, after all, the position is fixed so I don’t think it would be a problem.

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Just wondering, how were you communicating to the airplanes in vicinity?

Radio would require the planes to be listening on a specific frequency and ADSB Out would require the planes to have ADSB In which is not guaranteed.

It wasn’t an ADS-B, Transport Canada (the FAA equivalent in Canada) doesn’t like ADS-B on drones yet, so the solution was to have an SDR (BladeRF, full-duplex for Tx/Rx), the on-board SBC had a server the received the voice sample (either direct through ground station MIC or automated reading directions, alt, etc every X period of time) and then broadcasting it to the airband, so it’s simply:

Ground station mic -> internet -> server on SBC -> SDR -> airband (AM, I think it was ~120Mhz that time) -> other pilots

If you have the manual communication (where the drone pilot comms and not an automated broadcast), you can pretty much talk with pilots as if you are on-board.

I had a better write up if interested on how it works in here, in the “SDR” section.

https://tamim.io/professional_projects/nerds-heavy-lift-dron...

Super cool!

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