Noah Vawter (of Exertion Instruments) and I used to send each other voicemails encoded in a [pre] Nazi-era (OK, further research shows it was developed in the 1920’s) German radio protocol called Hellschreiber or Feldhellschreiber, invented by Rudolph Hell. It’s a sort of early paper-tape teletype system which was also the first example of bitmapped fonts. You can encode/decode using fldigi (available on apt in ubuntu and here: http://w1hkj.com/Fldigi.html). Despite its unfortunate origins, it’s pretty interesting as an early automated text-over-radio system which is robust mainly for the same reason people are good at reading CAPTCHAs.
Here’s a mechanical feldhellschreiber machine in red/blue stereo: http://unterbahn.com/2011/04/franks-n4spp-hellschreiber-page/
Finally got around to more coding this weekend, and put together part of an encoder, a bit messily but short enough to be readable. You can try it out here:
It doesn’t work.
I’m starting to get diminishing returns for my debugging and am pretty tired, so I’m just going to put this out there and think on it and/or see if I can get help from someone who’s a bit more methodical of a coder. Sometimes I’m a bit too much of an empiricist, not to mention a cobbler-together, impatient as I am to get to Hello World.
Also — once I get an encoder working, I really want to move on to a decoder, so you can run this on a phone facing another phone, and send/receive messages that way. How efficient and historically accurate!