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vga over Cat5e

5K views 30 replies 8 participants last post by  DeletedUserPost 
#1 ·
Hi, don't know if this is the correct place for this question...


So I am setting up a classroom with 25 monitors and have seen that using cat5e is no problem. Well I have been having problems. It's one monitor splitting the image to the other 25 monitors.


I am using solid utp cat5e cable.


I ran all the cat5e to a patch panel punch down 568B. At the other end I have it terminated to keystone jacks. I am using an RJ45 to vga (HD15) adapter to connect everything.

I can't post url's so if you go to eforcity . com and search POTHRJ45AD03 you will see what I'm using.



From the patch panel I have 2 foot patch cables with the RJ45 to vga adapter plugging into a 16 port VGA 300Mhz splitter


monoprice .com search 4087


I am using flat panel monitors with a native resolution of 1360x768 and have tried moving it down to 1024x768 and it's a little better but the main issue is a lot of ghosting.



Thanks
 
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#2 ·

Quote:
have seen that using cat5e is no problem

That's the problem.

VGA requires at least 3 75 Ohm coax cables to carry RG and B.

You're using 110 Ohm twisted pairs, the impedance mismatch is causing signal reflections (ghosting).

If you must use cat5, use the proper baluns to balance the unbalanced video signals and properly match the cables characteristic impedance.
 
#3 ·
Thanks for the replies.


Mark I don't know electrial terms at all. So please bear with me. I understand that the cat5e ohm is 110 and you are saying that is 35 Ohm over the vga spec.


What baluns could I use? Something like a ferrite?


I need a low cost fix for this.


Thanks!
 
#8 ·
I did make the cable from the instructables.com site and same issues. All the other options there are too expensive, the person doesn't want to spend money (of course).


at $180/each for the extenders that would come out to $4500.


 
#9 ·
Yes, it is not cheap. You want to do something that really is only used really in certain circumstances. Back in the day when computers were expensive, yes, you would see multiple monitors split off With the advent of terminal software like Teamviewer, DLP & LCD projectors, Whiteboards, it is easier to do through IP applications, or face to face with a projector, than having each individual sit at a desk with you expecting them to always be watching what the instructor wants them to see, when they can look up on the wall at the projector showing the same thing on a screen.
 
#10 ·

Quote:
Originally Posted by SAM64 /forum/post/21892399


He's feeding the same thing to 25 monitors, he needs a distribution amp, not a switcher, and the correct cabling or the proper baluns, not an expensive vga over ip device or multiple video cards.





Google "VGA over cat 5 BalUn"

I googled that and there are a ton of different options.


Does anyone have any recommendations on one's they have used?
 
#12 ·

Quote:
Here are some more if you are bored with the current choices http://audio-video-supply.markertek....00&isort=price BTW, they go as high as $38k.

Greg, why do you bother?

You provided a link to a bunch of matrix switchers, not BalUns. No BalUn is 38K.


Daryl, it might be cheqaper for you to replace the cat 5 with coax, if you don't want to spend the money on BalUns.
 
#13 ·

Quote:
Originally Posted by SAM64 /forum/post/21893505


Greg, why do you bother?

You provided a link to a bunch of matrix switchers, not BalUns. No BalUn is 38K.


Daryl, it might be cheqaper for you to replace the cat 5 with coax, if you don't want to spend the money on BalUns.

Thanks Sam64. I was thinking about coax but didn't know how that would work.


I would still need a splitter capable of 25 monitors; also what would I do have some other coax adapter to vga?


Thanks
 
#14 ·
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#17 ·

Quote:
Originally Posted by SAM64 /forum/post/21891233


That's the problem.

VGA requires at least 3 75 Ohm coax cables to carry RG and B.

You're using 110 Ohm twisted pairs, the impedance mismatch is causing signal reflections (ghosting).

If you must use cat5, use the proper baluns to balance the unbalanced video signals and properly match the cables characteristic impedance.

It sometimes depends on the application. I ran three 100foot shielded CAT5 lines for VGA in a security system. The display was 12 to 16 cameras per screen.


For that application, the artifacts caused by the cable were secondary to the poor quality video images being provided in the first place.


Now at home in my HT monitor wall I did use 5x 75ohm mult cable.
 
#18 ·
Sorry to bump an old thread, but I have a similar question.


I want to extend the monitor signal from a laptop. Monitor only, no mouse keyboard etc.


The wiring is existing in the house, and is plain Cat5, not Cat5e, but otherwise very good condition, modern cable. It's a homerun between both locations, no splices. The run is 100' or so.


I have seen the "VGA over Cat5" adapters on MonoPrice. Would this be okay in my application?


Do I even need to use VGA? I have not bought the display yet. Would I be better off buying a TV and using "HDMI over Cat5" ? Or maybe DVI?


Really, the only thing that is set in stone is the cable. Everything else I've yet to buy. I could get any adapters, any display, any laptop.


Thanks guys.
 
#20 ·
Yeah, would be helpful to know what you're trying to accomplish...


But you'll definitely have better luck with a VGA extender than an HDMI one. VGA signals will be much more forgiving with the "non-e" cat5.


Jeff
 
#21 ·
Thanks for the info on VGA vs HDMI. VGA will be easier anyway, as I may end up using an existing LCD monitor I have.


The main goal for the remote monitor will be to view a Megapixel IP cam feed. It will have other duties as well, like weather info etc. It will be mounted in a strategic spot in the house. It will be used as reference only, and will not need to act as a workstation in any way.


The laptop will not be 'mobile', and will not get much direct use. Hard to explain... It will act as a 'server' if you will, and it will be in a somewhat remote location. I will access it regularly via remote desktop. Everything is on the same network, all hard line, no wireless.


Laptop instead of desktop/server for a whole slew of reasons.


I have done all of this before, with great success. The only thing I didn't do before is the remote monitor. It was the only thing missing in my prior application. This time, all the components will be even better (cam quality, software, server etc)


I don't expect a perfectly clear, vivid, full high definition picture on this remote monitor. I won't be watching movies or anything. I just want a normal picture that I can view a higher end IP cam feed on, some desktop gadgets, and maybe some other things. No audio.


Think I will be okay with a regular 21" LCD monitor and Monoprice Cat5/VGA adapters?
 
#22 ·
For the OP, why not use some form of meeting / desktop sharing software (Lync, Skype, Communicator, Live Meeting, Go to Meeting, etc., etc.)? Use your existing Cat5e infrastructure and share the teacher's desktop. Not everything has to have a HW solution.
 
#23 ·
Klaus,

Can you use the existing Cat5 to pull Cat5e?
 
#26 ·

Quote:
Originally Posted by Klaüs /forum/post/22045098


I just figured all along it was regular Cat5, not sure why.

So, you ASSUMED...
 
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