I transmitted this way using a raspberry pi and a basic filter and antenna and was heard one day in New Zealand from Ohio. https://github.com/JamesP6000/WsprryPi
So, you thought that machine was airgapped....
Sleeper video of the year so far. All of that was fantastic.
And imagine that, quality content without “be sure to like and subscribe!”.
From the github repo:
>Because we rely on harmonics and aliasing, the primary frequency components emitted by your microcontroller are going to be in portions of the RF spectrum where RF transmissions are banned. Please filter your output or perform your tests in an area where you are unlikely to leak significant RF. The overall EIRP output is genreally ≪300uW across the whole spectrum spread out over hundreds of emission frequencies, but there is virtually no way a device deliberately transmitting on these frequencies could ever pass FCC part 15 compliance, even with filtering.
While low over the whole spectrum, on the desired harmonics the power is higher, just how far does it go. I'd also worry about getting into trouble experimenting with such things. Some wilderness areas utilize radio to track and monitor wildlife and resources, hopefully it wouldn't interfere with those. Though maybe it is not easy to get in trouble doing so because of the low power output.
This could be very useful as a covert channel on a hacked device, there goes your air gap!
wow, that is a great hack
I really liked the explanation of how he used harmonics to get to the frequency he desired.
Also, LoRa is really good when it comes to low power data transmission. To share a recent example, with just ~100mW of transmission power, they managed to fly an RC plane to a distance of 100km: https://www.youtube.com/watch?v=CYJ2UOrlXgM .(Their transmitter from the ground station was configured at a higher power, but the transmitter on the aircraft was transmitting telemetry back at 100mW throughout the distance)
Another related fun project is using raspberry pi gpio to work as an FM transmitter: https://github.com/markondej/fm_transmitter