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