I love this PoC, and I believe it might actually prove useful in certain situations. Short-range FM transmission is certainly possible with cheap devices [1] Modulating the FM signal should be a breeze, I'll try to hack up some code soon. Awesome project.
[1] - http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter On Sunday, March 3, 2013 at 4:25 PM, Jens Christian Hillerup wrote: > Hi, > > One thing I've been thinking a lot about recently is how to make > digital one-way communication feasible for activists, sort of sending > digital information to the broad public. I believe that FM is a good > medium for this because the transmitters are cheap and everybody has a > radio. Hook up the radio to your sound card, and demodulate the audio > back into data, and there you go. > > I did a quick hack back in September, called modulera [1]. The idea is > to exploit how pentatonic polyphony always sounds good, regardless of > the notes picked (as long as they're within the scale). The way it > works is that it takes three octaves of some pentatonic scale (in this > case F# major), and silence. This gives 16 different notes. Split up a > byte into two nibbles and you get your two tones. I realize this > approach has a way too low bitrate, but I like the aesthetic in having > the modulated data also be easy on the ears. For any real use, this > would likely need to be scrapped to increase bitrate. Feel free to try > the script, though! I've included the output of the script modulating > itself. > > I basically just wanted to throw it out here. Does anybody have > experience in modulating data? Has this kind of digital one-way > communication been done in an activist setting before? Does it make > sense to kick off a project aimed at creating a easily usable system > capable of modulating and demodulating data at modest bitrates > (>15KB/s)? > > JC > > [1] https://github.com/jchillerup/modulera > -- > Too many emails? Unsubscribe, change to digest, or change password by > emailing moderator at compa...@stanford.edu or changing your settings at > https://mailman.stanford.edu/mailman/listinfo/liberationtech > >
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