VGA Cable Limitation

Thanks.

You just solved a problem for me. Our president installed a projector on the ceiling of his office, and I know the run is not nearly 100 ft, yet his image has horrible ghosting.

Thanks a lot for your help to the original poster ... and to me

A good answer on your first post! That's very unusual! Congratulations and welcome to CR4!

I had no idea you could carry VGA that far with nothing but a cable!

Dick

Thank you for the info.

Hi,

Use good quality cable, I installed one of 30 metres and it works very well at 800x600 but at higher resolutions there is some jitter in the picture not present at shorter distances.

Peter.

VGA is not a high quality video signal, and yes, if it is a cheap cable you will run into problems.

However, if you do run into problems with signal strength, you can use a "repeater" in the chain to boost the signal.

In many situations, whether it is coax, video, HDMI, or VGA, I use a repeater that is either the same connection, or in some cases, run Cat5 for long runs and switch it back to the original protocol at the appropriate junction.

This works for me on networks and video signals.

check out this link: http://www.gefen.com/kvm/product.jsp?prod_id=3959

These solutions are costly and there are other cheaper alternatives, but at least I know that every single gefen component I have ever bought or sold has never died on me and every single client has been satisfied every time.

Or use a USB-VGA adapter: http://www.tigerdirect.ca/applications/searchtools/item-details.asp?EdpNo=1088606

I don't remember how long a USB cable could be. Maybe cheaper then VGA cable?

A good quality 30m VGA cable will work alright at the relatively low resolution of 1024 x 768 if the following two conditions are met:

1. a good quality cable is used.
2. there are no circulating earth/ground currents
3. the cable is driven by a good quality VGA output

1). for 30m cable runs you do need good quality cable. Professional installations would use larger than usual or a bundle of 5 coaxial cables (typically RG59 or equivalent for this distance)

2). It is likely the both the projector and the video source are earthed. If they are 30m apart the scope for circulating earth currents is large arising from differences in earth potential or induced interference. If you are in a public building in the UK with an induction loop hearing assistance system you will almost certainly get serious interference with the image.

3) The VGA output of some equipment is inadequate to drive long cables especially on some laptops, but some video cards have problems too. If this is the case a small booster amp may be needed. (I have had problems with some cards driving even 15m, but others cards have no problems).

If interference from circulating earth currents is a problem you will need an isolated line driver system. The most cost effective way is to use active VGA to Cat5 extenders. These can drive much greater cable lengths and use cheap Cat 5 cable for the link.