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 [email protected] or changing your settings at https://mailman.stanford.edu/mailman/listinfo/liberationtech
