pixelvision concept (fwd)

["Alexander the Great jr." <kanaris@bode.usc.edu>]

> 

> i have a possible idea for something that would be like a pxl, only 

> color.  i've talked with some knowlegeable friends and they say that if 

> i find the right adapter, and a camcorder without a recording device, i 



A camcorder WITH a recording device would work as well. Simply, you

don't use the recording device, only the signal output. 



> could possibly hook it up to an audiocasset recorder the same way that a 

> pxl does and get the same effect.  what do you think?



I think NO WAY! An audio tape does not have sufficient bandwidth to store

more than 400 pixels at the NTSC resolution. 

Think of it this way: The scanning rate of NTSC is 15,734 Hz

The highest frequency you can record with a good cassette deck using

Chrome or Metal tape is 16KHz or 19KHz respectively. (As measured on

my Denon and Aiwa, both of them hi-end units).



That means you have enough bandwidth for about 1 PIXEL per horizontal

line! In other words, each and every TV line has to be black or white!

This method of recording does not allow you to record the sync pulses

(which require much higher bandwidth) so this trick DOES NOT WORK

AT ALL, but it just gives you an idea of where you are and where

you have to go. 



PXLvision works because it uses a higher than normal tape speed,

8x or something like that, which roughly allows for 8x bandwidth,

then trades off vertical resolution for horizontal resolution.

So, instead of 400 horizontal lines, you get only 100. That gives 

you four times more pixels per line. 





    <<alex kanaris>>  



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Alexander Kanaris                           ___   ___     kanaris@bode.usc.edu

Electrical Engineering --- Systems   /  /  /__   /      kanaris@thales.usc.edu

University of  Southern California  /__/  ___/  /__     kanaris@aludra.usc.edu

Los Angeles, California 90089-2562                  kanaris@alumni.caltech.edu

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