Christmas message (Warning: Loud audio!)

To decode the message, follow these steps:

  1. If you don’t have phyphox installed, explore phyphox.org to learn what it is. Then follow the download buttons to install it on your phone.
  2. Visit this page on your phone.
  3. On your phone: Click this link to open the decoder in phyphox. Start the experiment.
  4. On your PC or any other device: Play the video, so the phone can hear it and watch the result on your phone. On slower phones it may take longer to see a nice results.

How does this work?

Each tone you hear is actually two tones of different frequencies at the same time (if you are technically inclined: like DTMF tones). Phyphox analyses these tones to extract both frequencies (for those mathematically inclined: it is done using a Fourier transform) and draws a point at a position given by both frequencies. So, the first frequency (in the lower range) gives an x coordinate and the second one gives the y coordinate. Eventually, all those points form up an image.

Create your own message

You can create your own message using the generator. Just drag your image into the editor and download the audio file. Small images with strong thick lines work best. Dark pixels in your image will be orange in phyphox and bright pixels will not be transmitted.