VGA over CAT5e

Oct 06, 2008 22 Replies

(some newsgroups removed) Rich Seifert wrote: (snip)

(and later wrote)

I could get out pencil and paper and go through it.

It seems to me that in the series configuration the current in the center conductor of the coax is the same as in one wire of the balanced line. Also, that the transformer has to be configured so that the shield is at 0VAC. Again, with out actually drawing it on paper, I believe that indicates a 1:1 transformer.

-- glen

snip

mmm wouldn't surprise me. I've seen VGA extension cables as short as 2M exhibit ghosting.

P.

There are well built VGA extension cables (use 75 ohm mini coax cables at least for RGB signals). Those work generally well. Also there are those crappy cables built just from general purpose computer cable with lots of wires inside one outer shield. Those cheap cables have typically wrong impedance and considerable crosstalk between signals -> ghosting problems

Then the used resolution + refresh combination has effect. Almost any crapphy cable works for 640x480 60 Hz resolution but for 1280x12o4 and higher resolutions the quality of the cable starts really slow up.

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