binary-fsk

streaming encoder/decoder for binary frequency-shift keying

https://en.wikipedia.org/wiki/Frequency-shift_keying

STATUS

Work-in-progress. Works great if you pipe the encoder to the decoder, but still working on getting it working well in noisy / real-world environments!

Usage

Let's encode the string 'Hello!' into sound waves and then back again to a string:

var bfsk = require('binary-fsk')
var speaker = require('audio-speaker')
var microphone = require('mic-stream')

var opts = {
  mark: 884,
  space: 324,
  baud: 5,
  sampleRate: 8000,
  samplesPerFrame: 320
}

var encode = fsk.createEncodeStream(opts)
var decode = fsk.createDecodeStream(opts)

// pipe to your speaker
encode
  .pipe(speaker())

// receive sound from your speaker and decode it back to text to print out
microphone()
  .pipe(decode)
  .pipe(process.stdout)

// write a message!
e.end('heya!')

This will make your computer scream garbage at you (make sure your speakers and microphone are on!) briefly, but it should then output

hello warld!

API

var bfsk = require('binary-fsk')

bfsk.createEncodeStream(opts)

Returns a Transform stream. Pipe text or other interesting data into this, and it will output audio data. You can pipe this to your speakers.

Valid opts include:

mark (required) - the "mark" frequench, in hertz. This frequency is used to
signal a '1' bit.
space (required) - the "space" frequench, in hertz. This frequency is used
to signal a '0' bit.
baud (required) - the number of bits to transmit/expect, per second.
sampleRate (optional) - the number of samples per second. Defaults to 8000.