Transmitting from your computer using RFI

[ChrisSmolinski]

Here's my Mac Book Pro (2010 model)  playing Mary Had A Little Lamb over the radio, by modulating the RFI (Radio Frequency Interference) produced by it and other computers. As picked up on a Sony 7600G receiver. I found the best reception was on the long wave band, although I could continue to hear it well above the AM (medium wave) band, past 1700 kHz. The signal was pretty much everywhere, no matter where I tuned, in 1 kHz steps.  

Picking up radio emissions from computers is one method that can be used to spy on them.

I used the source code available here: https://github.com/fulldecent/system-bus-radio

If you want to see some radio related software I've written, please visit http://www.blackcatsystems.com

https://www.youtube.com/watch?v=l8AYHnF8ZrA&feature=youtu.be

[youtube]l8AYHnF8ZrA[/youtube]

[Fansome]

Stopping such transmissions was one of the goals of the Tempest regulations promulgated by the government.

Tanenbaum, in one of his classic textbooks, has a brief section on how a rogue application could transmit data by modulating its cpu usage, so that noise, power usage, and other externally observable aspects of the system could be monitored for information  sent by the application. Even though such transmissions would be noisy, that could be overcome by using forward error correction.