HFU HF Underground
General Category => General Radio Discussion => Topic started by: ChrisSmolinski on September 04, 2013, 2347 UTC
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Over on Reddit, user cronek discovered by using his RTL-SDR that the microphone on his HP EliteBook 8460p laptop computer was continuously and unintentionally transmitting the audio from the built in microphone at 24 MHz in FM modulation. He found that the only requirement needed for the microphone to transmit was that the laptop needed to be turned on – even muting the microphone did nothing to stop the transmission.
I accidentally stumbled upon a signal in the 24MHz range, appearing to be 4 carriers. I tuned to it and heard silence, then someone came into my office and started talking and I could hear them speak. The signal appeared to be coming from my other laptop (not the one running the SDR) and was pretty weak (my antenna, the crappy one that comes with the dongle, stuck to a metal stapler was right next to the HP laptop).
http://www.rtl-sdr.com/potential-major-security-flaw-hp-laptop-discovered-rtl-sdr/ (http://www.rtl-sdr.com/potential-major-security-flaw-hp-laptop-discovered-rtl-sdr/)
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Woah! :o
24MHz wouldn't go very far. What about harmonics?
Peace!