This is probably the stupidest question to ever grace the halls of GQ, but when you go into electronics shops you see like 20 TVs, each one of them showing only a section of the big picture.
How do they do that? I’ve always wondered. I can figure out how you’d make them show all the same (full) pic, but not sections.
They do it with a magic doohikey that splits up the incoming video signal into 25 separate signals. (You generally want a square number.) So it divides the incoming signal into a 5x5 grid, takes each box and blows it up to a full size video signal, yielding a new signal with really crappy resolution. You then connect one output to each monitor, and put the whole display really high up or far away so people don’t realize how bad it actually looks.
The same way some computers can output pieces of one image to multipl monitos. We had computers at work that divided the image and sent it to multiple monitors.
We also had a large screen made up of four 50" screens. There was a hardware box that took the signal and assigned 1/4 of the image to each of the four TVs.
Wow, where can I get me one?
Thanks, friedo. I figured it was something like that. How does it split up the signal?
A magic doohicky. Oh OK, now I get it. 
The newer ones probably use fancy digital stuff, but the older ones had a very accurate timing circuit that would listen to the scanning signal and increase the wavelength in an analog fashion. So, for example, it would wait for the scanning signal to go 1/5 the way accross the usual frequency range, take that wave and streeeetch it out to a full size wave, and send that as a single line to the upper left monitor. Then do the same for the other 4/5 of the line. Then the scan drops down and reverses, rinse and repeat 524 times until you’ve done the entire signal.
Is this something you can do with sound waves, too, or only light waves?
I mean, I have a basic knowledge of the difference but I am curious now if there was some way you could do it.
I figure it would be gibberish, though, right? Or could we understand a radio wave that’d been stretched out like that?
It occurs to me we’re not talking about light waves per se but TV waves, which are a little different.
So my question is properly: can they do this somehow with radio waves, not sound waves.
Or are the frequencies too long (or short)?
Technically, it’s doing it to waves of fluctuating-voltage electric current, so yeah the process could be applied to any other signal.
Just to take a sound recording and stretch it out 5 times? A good piece of sound editor software can do that to an audio file, but it’d sound very weird.
Two different questions are being answered here.
As a side note, some computer systems can essentially allow the same parsing of image. You can use Windows XP to accomplish this by going into the Display menu and finding out where to click to have an external monitor, or secondary monitor, seen as a section of desktop instead of as a clone of full desktop. In this way, you could have a shared image where two monitors ( or, a laptop LCD and a desktop monitor ) have the desktop split. It’s always cool the first time someone sees a cursor be moved across the left-hand monitor towards the right-hand edge…and then seamlessly appear on the right hand monitor along it’s left-hand edge. 