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Lawrence

Type of video transmission cable for 20-40m

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Hi Folks,

I'm using a Dell workstation with Quadro P2000 as display computer, outputting 3 sets of HDMI signal at [email protected] to projectors. On the display card end, I used DP to HDMI adaptor, then two shorter paths (15-20m) I use HDMI cables directly, while the longest one is about 25m, I use Kramer HDMI to cat5 extender.

There is no issue about the HDMI direct cables but I consistently experience video signal interrupt once a day, happens at random time. We used Kramer extender before and its quality is good, so we thought maybe our Cat5e cable was not good enough or there was some noise, or maybe the projector had problem. We switched to use the latest HDMI fiber cable (the cable core is optical fiber, not an extender type) and swap another projector, but after a few days, same things happened. For your info, all projectors are BenQ PU9530. Most of the time the video signal is disrupted and resume after a while, there are times that when picture resume, Watchout display was minimise and need to remote control it to bring it back to the front.

I discussed this with various person and they had diverse options, some said that HDMI has the 5Vdc pin and the line voltage drop as it travel long distance, so the more ports you are using, the higher voltage drops you will experience, but I tried using the computer to output only the longest video signal, and the problem still exist with only one video port. Some said all those extender, fiber cable are unstable and only the HDMI cable with embedded amplifier is stable.

So what are you using to extend video signal beyond 20m? Do you tend to use less than 3 ports per card?

Regards,

Lawrence

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Lawrence,

There are two points which are important. When WATCHOUT - or rather Windows - looses contact to a display it usually means that it does not see a valid EDID information on that port anymore and since we are using digital signals today Windows will just close the output on the graphic card. WATCHOUT will notice this and will show the error message that it detected an unexpected display configuration change. A way to stabilize this at least for WATCHOUT would be to use EDID minders behind the graphic card outputs (short good cable in between) and make sure that the EDID minders only hold one valid resolution.

The second part is the extension side. This is basically a question of quality cables and/or quality extenders. From my experience, Kramer products are not on my list of quality products here anymore. If you go for CAT-extenders, use quality brands and good shielded CAT cables with CAT-5e or better CAT-6 specification. Or use good optical converters and glass fibers. Another option could be to use HD-BaseT solutions and good cables. Many manufacturers offer solutions over IP today which give pretty good results, though most of those solutions use compression algorithms.

//Rainer

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2 hours ago, RBeddig said:

Lawrence,

There are two points which are important. When WATCHOUT - or rather Windows - looses contact to a display it usually means that it does not see a valid EDID information on that port anymore and since we are using digital signals today Windows will just close the output on the graphic card. WATCHOUT will notice this and will show the error message that it detected an unexpected display configuration change. A way to stabilize this at least for WATCHOUT would be to use EDID minders behind the graphic card outputs (short good cable in between) and make sure that the EDID minders only hold one valid resolution.

The second part is the extension side. This is basically a question of quality cables and/or quality extenders. From my experience, Kramer products are not on my list of quality products here anymore. If you go for CAT-extenders, use quality brands and good shielded CAT cables with CAT-5e or better CAT-6 specification. Or use good optical converters and glass fibers. Another option could be to use HD-BaseT solutions and good cables. Many manufacturers offer solutions over IP today which give pretty good results, though most of those solutions use compression algorithms.

//Rainer

Dear Rainer,

Interesting, I knew a bit about this and have been trying to imitate this by saving EDID on the extender, setting EDID file on PC but I think it is still different from a dedicated hardware to do so. I think I’ll have a try. There are many brands and may I know what brand you recommended?

Regards,

Lawrence

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Our standard solution used to be to use a DVI Parrot to define a single resolution and then to use the DVI Parrot as the source for a bunch of cheaper Gefen DVI Detective units. Then the graphic will only see one resolution which is even more important when you try to use 50fps resolutions. All displays have their preferred resolution in the 60fps range and are sometimes a bit unwilling to change to 50fps.

Good EDID minders are also those of Lightware or http://www.spatz-tech.de.

Internal EDID management could be an option and is probably the choice to use when it comes to UHD or 4K since there are not many EDID minders available for resolutions above WUXGA.

 

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