I’ve just watched the recently released Techmoan video titled “Sony’s forgotten ‘80s Picture Phone”. As with all of his videos, I found it quite interesting and he has uploaded the audio files so I could do an attempt at trying to decode it.

I’ve uploaded a copy of the audio file Here for posterity.

First attempt

My first attempt at trying to decode the audio file resulted in me opening the audio file in Audacity:

audacity clean

For those who are familiar with recordings of e.g. Commodore 64 tapes, a few things become immediately obvious:

  • the signal starts with a 400ms sync pulse
  • the signal proceeds with a 400ms pause
  • the data stream is being sent
  • the data stream is terminated with silence

Having a closer look at the sync pulse produces an immediately recognisable pattern:

sync pulse 1