Sending IMAGES via SOUND! #shorts

While thrifting with friend of the channel Clemens we found an SSTV receiver. I had never heard of the term SSTV, but the device looked to intriging I just had to take it home. Also, it was only 2.5 euros. But what is it, what does it do and does it still work?

What I bought is a Robot Research Inc 70A SSTV receiver.
It doesn’t appear to be working. Opening up the device we find a date code. 1978!
After pulling on the brightness knob the old beast awakens. The screen still works!

What follows is a long night of reading online, experimenting with inputs, looking on Youtube and fiddling with knobs. But after a few hours we get an image on the screen.

The technique this receiver uses is know as SSTV. The model I have only supports the following format:

  • 8s (8 seconds, althought it might also be 7 seconds as that is pal 50hz)
  • 120×120 pixels
  • 15 lines per second, to make 120 lines in 8 seconds
  • The vertical sync pulse has a duration of 30ms, and the horizontal sync pulse duration is just 5ms
  • The sync frequency is 1200Hz, and black and white interpolate between 1500Hz and 2300Hz
  • The aspect ratio is 1:1 (to match the usual oscilloscope tubes of the day)

Can anybody help me encode images using the parameters descibed above?

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