Are there any audio data transmission protocols that use the full spectrum of sound a microphone and speaker can typically produce instead of just those frequencies that work on a POTS line?
This is what modems do.
AudioTransmit – Transmitting data between computers using audio
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Re: AudioTransmit – Transmitting data between computers using audio
#22Interesting, but it would be much more efficient using something like QAM, because with binary tones most of the bandwidth is wasted.
Re: AudioTransmit – Transmitting data between computers using audio
#23This technique is used a lot in eurorack modules for firmware updates. For example:
Re: AudioTransmit – Transmitting data between computers using audio
#24This will alternate between two different tones, one representing 0 and another representing one, each bit lasting 50 ms, giving a bitrate of 20 bits/s. This is obviously rather slow, so more a fun weekend experiment than a practical tool. There is a really deep rabbit hole when it comes to doing this more efficiently, getting into signal processing, modulation, encoding, error correction and more. And of cause, thin…
> bitrate of 20 bits/s I can imagine this being used as a control protocol for home/building automation, 20 bits is quite a lot if you consider each bit a device being turned on or off only. I still don't know why would anyone do this instead of wifi, but definitely way cooler. Also, anyone visits you the first time, there's a guaranteed 20 minute talk about the setup :)
Would make for a pretty stealthy bootstrapping protocol to share things like wifi keys between devices or to do keystroke logging.
Re: AudioTransmit – Transmitting data between computers using audio
#25zmodem or xmodem?
Re: AudioTransmit – Transmitting data between computers using audio
#26When I started programming, the computers would save their programs in a common tape record. People would usually type programs printed in magazines. We even had a radio program in Brazil that transmitted programs as if it were music.
Re: AudioTransmit – Transmitting data between computers using audio
#27Minimodem is a similar piece of software, but much more flexible. Depending on the quality of your link, you can adjust the symbol rate, as well as the frequencies to signal 1's and 0's.
Still (as said before) not more useful to me than as a weekend project. I used it a few times with my CB radios to see how far I could transmit 1200 and 300 baud.
Re: AudioTransmit – Transmitting data between computers using audio
#28This will alternate between two different tones, one representing 0 and another representing one, each bit lasting 50 ms, giving a bitrate of 20 bits/s. This is obviously rather slow, so more a fun weekend experiment than a practical tool. There is a really deep rabbit hole when it comes to doing this more efficiently, getting into signal processing, modulation, encoding, error correction and more. And of cause, thin…
I've played around with techniques like this too. My thought was to make a multimedia tape zine where people could submit songs and accompanying short text. One track of a stereo cassette track would store the audio mixed to mono, the other would store the text encoded something like this. You'd play the tape in a cassette player outputing to a computer that would play one track to a speaker and decode the other to a…
I've been a bit obsessed with the idea of running an 80's themed ARG, and this would be perfect.
Re: AudioTransmit – Transmitting data between computers using audio
#29I'm impressed by how compact this is, but if anyone is looking for a more "production-ready" solution, I've had great success with ggwave [0] - it even sounds pretty decent in the slow modes (as well as having an ultrasonic mode).
Obviously you won't be using any of this for regular communication, but there's a whole world of cool uses for sending short (up to a few bytes) messages over the air. And despite knowing dial-up modems exist, people are constantly impressed by novel applications of it.
Re: AudioTransmit – Transmitting data between computers using audio
#30Wheel successfully reinvented :) Nothing stopping you setting up a whole AX.25 network between multiple machines using Dire Wolf [1] and the built-in AX.25 [2] (a derivation of X.25) support still in the Linux kernel. You get a proper network interface that shows up alongside eth0. Nice short instructions at [3]. Just don't hook it up to radios unless you're appropriately licensed. Speakers and mics only. [1] https:/…
Also the "BadBIOS" hypothetical malware from 2013 that spreads via computer speakers & mics [1].