3 ms·

If you need a datapoint on how noisy those signals are: some people have combined a 144.6Mhz Raspberry Pi output with a narrow passive bandpass filter to genera

• a-priori 13y ago
  Yes, assuming there's strong harmonics (I'd be real surprised if there weren't), you should definitely put a bandpass filter between the Raspberry Pi and the antenna like these guys did. Thanks for the link! That's a clever way of using harmonics to your advantage.
• aortega 13y ago
  Recently I did a similar project in which a malicious hardware device leaks a victim's data (Password, credit card #, etc.) through a similar technique. We used an FPGA though, so with a 100 Mhz fundamental frequency we had harmonics well into the 1.5 Ghz. We called it CPU-SDR. Video here: https://sites.google.com/a/groundworkstech.com/index/blog/rsa-2014---about-cpu-backdoors-and-data-exfiltration https://sites.google.com/a/groundworkstech.com/index/blog/rs... Bonus: Using mutiple PCB traces, you have a basic Yagi-like directional antenna. Feeding different traces you can modify the RF radiation pattern it in real-time.
  • jrockway 13y ago
    You've indeed invented MIMO.
    • aortega 13y ago
      It's more like a Yagi, as currently I feed only one of the "antennas" and the modulation is very limited. But messing with the phases should be possible.