Dear Chris, RF actually! Thanks, Abhinav
On Tue, Jun 7, 2016 at 10:11 AM, Christopher Richardson < [email protected]> wrote: > Hi Abhinav, > > This sounds really interesting! > > Are you using RF or ultrasound out of interest, to grab emissions from the > SMPS? > > cheers > > Chris > > On Tue, Jun 7, 2016 at 6:35 AM, abhinav narain <[email protected]> > wrote: > >> Hi all, >> I am trying to make a covert communication channel using SMPS noise >> generated by the processor as a part of my research. >> >> I see a change in frequency emitted by the processor when I run the >> following loop (http://pastebin.com/uRghLuLm) with message variable >> containing the message, and see the spectrogram ( >> http://postimg.org/image/g0ec0nvqj/full/), with fluctuating red points >> ~60kHz, indicating the change due to a loop and sleep executed on the >> processor. >> >> I want to decode the bits and I think I should use FSK, although I lack >> understanding to configure the details. >> The following is the current flowgraph where I have used bandpass filter >> to narrow down the signal to ~60kHz and using quadrature block to >> demodulate. >> >> Since the entity of interest is actual SMPS noise of the laptop adapter >> instead of a sinosoid, I have no clue how to write a clear decoder after >> looking at some tutorials of GNU Radio to know the symbol rate etc for the >> clock recovery algorithm. >> >> I would be grateful, if someone can guide me on how to proceed >> >> >> Thanks, >> Abhinav >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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