I'm interested in capturing analog video in NTSC and transmitting it as efficiently as possible over a digital link, preferably while maintaining as much fidelity to the original signal as possible. My thought was that the video signal might be able to be sampled with a high-speed ADC, the samples transmitted, and the signal reconstructed at the other end with a DAC. Is this possible? If there's a better way of doing this, by all means share!
Transmitting NTSC over digital link
analogdigital-logicntsc
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Draw on paper.
Post anywhere OR email to me and I will post. apptechnz@gmail.com.
ANY diode in the signal path will affect accuracy badly.
Probably error of about +/- 0.1V best case or 2% at 5V or 20% at 0.5V.
If you must multiplex ADC use a "real" multiplexer IC to start.
The cheap CD4051 (HEF4051 etc) 8:1 multiplexer will do well enough for playing.
Pricing here - in stock from 52 cents US in 1's.
eg see below. They use an external ADC but the method is identical for onboard ADC.
Interlaced scan composite video signal isn't easily convertable to similar progressive-scan signal. You need to store the whole frame into some kind of memory and resend it at different speed using progressive scan. The simpliest way you will need a DAC-ADC pair with Fq about 6.5 MHz, an SRAM or ADRAM unit capable of running at 13 MHz clock and holding two frames, and the logic to control both input and output address. This way you will be able to store two interlaced half-frames and resend them back as progressively-scanned frames.
Everything said above applies to monochrome images as I don't know how any color-coding system works with progressive scan.
The image produced is likely to have visible interlacing artifacts, especially if there are horizontally moving objects in the image. It's a quite difficult task to remove them, but if you really want to reduce them, the better option is to have a PC with a analog video capture card and a program that processes and displays the image captured.
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Best Answer
Yes it is possible 100%. A little inefficient due to blanking intervals but 100% possible. You should get some 50-100Mhz+ 8-12bit ADC + DAC on other side.
But transmitting 8x100Mhz signal might be a problem for long distance.
If you are really cool you may encapsulate it into 1G Ethernet :-D