by Steve Anderson » Mon Nov 25, 2019 3:47 pm
The brick wall you hit is always bandwidth - the amount of information sent down a communication channel.
SSTV was originally 120x120 pixels per frame, monochrome, at about 7-8 seconds per frame. This requires a bandwidth of about 1kHz - easily fits down a phone line or via HF Amateur Radio.
NBTV may only be 32x48 pixels per frame (using a common-ish arrangement) but the frame rate is 12.5 frames per second. This will not fit down a telephone line or via HF radio as the bandwidth required is in the order of 10kHz, ten times greater - and no sound. (Neither does SSTV, but SSTV is really a sequence of stills).
It doesn't make any difference how you 'chop up' the signal it still needs to get from one end to the other intact. You can't send every other character in a book and hope it'll be understandable. Sure, you can compress signals, Winzip, jpeg etc. but there's always a trade-off somewhere.
Steve A.