Open standard for M2M data via audio?

Question

Is there an open standard for transmitting M2M data via audio?

Use case example: I want to broadcast a public PGP key via some sort of audio output.

Answer 1

I hope someone can provide a simpler solution but so far I've found that a process called modulation was used to transmit data over audio in the days of dial-up:

Data to audio and back. Modulation / demodulation with source code

Answer 2

If time is not critical then DTMF - up to roughly 10 signs or 40 bits per second.

Answer 3

You want to use "Frequency Shift Keying". It works by encoding bits into different frequencies of tones.

If you're doing that on Linux, use Mini Modem (http://www.whence.com/minimodem/).

If you are trying to accomplish this on windows, there are a number of amateur radio tools that transmit FSK signals over a soundcard. Try googling for "Sound card FSK modem"

Just for fun, here's a link to the "Kansas City Standard", which was intend for storing data on audio cassete: https://www.wikiwand.com/en/Kansas_City_standard