make install;

some notes to myself



SDR and airplane transponders

Written on August 24, 2015

One project that I’ve just started fooling around with involves airplane transponder transmissions. It turns out that with a software-defined radio USB dongle (<$30 on Amazon or <$10 on Ebay from Hong Kong) you can grab the transponder signals from planes (which (generally) have data elements such as ICAO code, altitude, speed,lat, long, etc.).

I was doing this on a Raspberry Pi and was feeding the data to FlightAware - they’ll give you a premium account for doing so. Clicking around, I realized FlightAware hides info about some planes from you. That stinks.

Recently in the news there have been stories that the FBI has been flying surveillance planes over several cities. Hmm… FlightAware conceals some aircraft identification data from you and the FBI is trying to conceal the fact that they’re flying planes over us. That’s odd. One thing to do would be to decide that you’re just going to dump your collected transponder data onto the internet so that anyone can analyze it. But since servers can be seized, you may decide to use a distributed file sharing technology - such as a blockchain…

It also occurred to me that it’d be important to have accurate data related to the geographic location of the radio receiver, so I purchased a GPS receiver from Adafruit for ~40$. In addition to the lat/long/altitude, GPS also provides you with an accurate time. Ihe GPS receiver also accepts a battery so you can keep the clock going if you lose GPS signal or can’t connect to an NTP server. I’ve written a small bit of code to integrate the GPS location with the aircraft data. (This may be helpful if you wanted to drive your car over to an airport parking lot and collect data.)

Regarding saving it with a distributed technology, there are a few different options floating around that I’m still researching/playing around with - IPFS, Alexandria, encoding it directly into the Florincoin blockchain, etc.