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 <abhinavnarai...@gmail.com> 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 > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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