What about digital NBTV?

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What about digital NBTV?

Postby emeaexe » Thu Mar 07, 2019 7:17 am

Hey! I've been interested on NBTV since quite some time and I've got an idea, maybe it could be interesting for you, guys.
What I'm thinking on is building a receiver/ transmitter that, instead of using a nipkow disk or a mirror drum/ screw it uses an LED or photodiode array.

LEDs didn't exist back in 1926 and it took a long time for they to become the cheap silicon diodes we have today, so this idea is to break down some "classical ideas"

It's wrong say it'll be digital, though. Because I'm thinking opf making the transmission and actual storage on an analog way (Simply using voltage levels, not discrete signals) and the scanning mechanisms could be something like a guy on the early 1900 used for the first television demostration ever. He used a lamps and photocells array and he mechanically switched one or other on and of to transmit the picture cell by cell/ lamp by lamp.

I've done some math and calculated an example resolution in pixels for the NBTVA club standard: 32 x 48. Basically what I've done is take the number of lines and knowing the aspect ratio is 3:2 then I deduced that one unit was 16px, since the shorter side is 2 units and that side in lines is 32. For the side being 3 units I multiplied 16 (one unit) by 3, wich gave me 48. I hope you understood, my english may seem fine but when I have to explain something complicated I go crazy :D

For the final thing I converted an image of Felix The Cat to that resolution, resulting on a really well accurated reproduction of the original, with no loses at all. Here ar the images: (Notice the one that's been converted is really small, the size it would appear on some nipkow disks!)
Original - Screenshot from NBSC player NBTVA club standard
felixx.png (78.33 KiB) Viewed 235 times
Altered resolution from the original - No changes on quality!
felixDigitalNBTV.jpg (1.53 KiB) Viewed 235 times
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Re: What about digital NBTV?

Postby Harry Dalek » Sun Mar 10, 2019 2:16 pm

Using led's for a rotating display and using a photo diodes for a camera are things that have been thought of before ...
Matrix led monitor display has been done a few times and very well .
You have to think out side the box when doing the rotating led idea or you will have to use a communicator and brushes noisy and friction but they have been made to work even back first in the 30's a wiring nightmare as well .
I dabbled with induction to power and modulate the led's only on a test proof of concept test and it would work well if you want to try that .
To do a larger screen you have to either still make a over large nipkow or drum or ....compact with a second framing drum disk to block out the leds ...or switching the leds on and off per line and do it with electronic switching ...may as well go full matrix on that idea .
Lots of ways to make mechanical Television ,i would read the old posts which i mention a bit as most of the ideas you are thinking about are on the forum in past posts ..you could do a search or best go to the start of the forum and browse whats been done over the years .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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