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Author Topic: High-Resolution Computer Signals Over Long Cable Runs  (Read 3961 times)

Collin Donohue

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High-Resolution Computer Signals Over Long Cable Runs
« on: December 01, 2011, 10:39:36 am »

Out of curiosity, what has everyone seen for long computer runs (between 100-200 feet) when your resolution is up in the ballpark of 1920x1080?  We're fine with HDSDI for some applications, but not all of our seamless switchers and projectors have HDSDI ins/outs.

From what we've tested, VGA/RGBHV DA's and cables all have bandwidth limitations, and we can't get the signals to go all that far before becoming unusable.

We also have tried DVI, but it's not always a solid signal and tends to get "snowy" over longer distances, even with amplification/equalization.

We haven't done extensive testing or research yet, but just wanted to see what other folks are doing for HD computer applications.

Also, this is for rental and staging, so rugged solutions are a must.

Thanks!
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Jeff Baumgartner

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #1 on: December 01, 2011, 04:58:25 pm »

I use CAT5 extenders.

http://www.gefen.com/kvm/dproduct.jsp?prod_id=1463

Is a cheaper one that provides decent results.
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Jeff Baumgartner

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Brad Weber

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #2 on: December 02, 2011, 04:21:18 pm »

Out of curiosity, what has everyone seen for long computer runs (between 100-200 feet) when your resolution is up in the ballpark of 1920x1080?  We're fine with HDSDI for some applications, but not all of our seamless switchers and projectors have HDSDI ins/outs.

From what we've tested, VGA/RGBHV DA's and cables all have bandwidth limitations, and we can't get the signals to go all that far before becoming unusable.

We also have tried DVI, but it's not always a solid signal and tends to get "snowy" over longer distances, even with amplification/equalization.
I don't understand the RGBHV/VGA comment as there are the same basic bandwidth and loss limitations and issues with SDI and DVI.  For reference, HDMI 1.0 defines support for up to 1920x1080@60Hz with 24 bit color depth and a bandwidth of 165MHz.  HDMI 1.3 upped that to 340MHz to support higher resolutions and scan rates and Deep Color.  Single link DVI is also 1920x1080 and 165MHz bandwidth.  Given that many VGA/RGBHV DAs are 350MHz or greater bandwidth, I don't see that to likely to be a significant limitation.

The one major factor you don't seem to note is what cable was involved and that is a critical factor in the resulting losses and potential run lengths.

UTP/CAT extenders are probably a good option in many rental and staging applications, especially as cables are pretty easy and inexpensive to replace and/or have spares. And you can get ruggedized CAT cable if desired.
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Collin Donohue

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Brad Weber

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #4 on: December 02, 2011, 06:00:47 pm »

Hi Brad... This is the cable we use:

http://www.extron.com/mobile/touch/products/product.aspx?id=5condmhrbncmbncmc&subtype=54#home
The mini-high res cable is 26AWG, http://media.extron.com/product/product.aspx?id=bnc5mhrcable&subtype=477&s=4 is the bulk cable used for those and shows the losses as -7.7dB/100' at 200MHz and -11.5dB/100' at 400MHz.  Compare that to the 24AWG RG-59 version, http://media.extron.com/product/product.aspx?id=mini59flex5&subtype=388&s=4, with losses of -5.8dB/100' at 200MHz and -8.3dB/100' at 400MHz and the 18AWG, RG-6 version, http://media.extron.com/product/product.aspx?id=shrcb6&subtype=477&s=4, with losses of -2.9dB/100' at 200MHz and -4.6dB/100' at 400MHz.  Much lower losses with the heavier gage cable and why I typically specify the larger, lower loss cable for longer runs.
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Justin Dodd

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #5 on: December 03, 2011, 01:05:37 pm »

I'll use DVI over Fiber for most HD cable runs over 50'
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Collin Donohue

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #6 on: December 03, 2011, 01:07:58 pm »

I'll use DVI over Fiber for most HD cable runs over 50'

Is there a specific product you like to use?  Any durability problems?
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Jordan Wolf

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #7 on: December 07, 2011, 12:02:02 am »

Is there a specific product you like to use?  Any durability problems?
We had a tour come through our hotel and brought in a 3 300' reels of DVI-over-fiber at their request.

The rental company apparently decided to go with non-ruggedized fiber cable, so we had to be a bit more gentle than we thought.  We kept it away from walkways, etc. and made sure bends were not too extreme.  There were no issues that I am aware of.

The DVI connectors at each end were permanently attached and had jacks for DC power, which I thought was cool.  The cable terminations (on both ends) were similar to or, possibly, the same as this cable.  I don't know if they are field-repairable, but they seemed fairly rugged, especially with the larger pins on the DVI connector.
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Jordan Wolf
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Clayton Ganzer

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #8 on: February 13, 2012, 11:01:59 am »

I don't understand the RGBHV/VGA comment as there are the same basic bandwidth and loss limitations and issues with SDI and DVI.  For reference, HDMI 1.0 defines support for up to 1920x1080@60Hz with 24 bit color depth and a bandwidth of 165MHz.  HDMI 1.3 upped that to 340MHz to support higher resolutions and scan rates and Deep Color.  Single link DVI is also 1920x1080 and 165MHz bandwidth.  Given that many VGA/RGBHV DAs are 350MHz or greater bandwidth, I don't see that to likely to be a significant limitation.

The one major factor you don't seem to note is what cable was involved and that is a critical factor in the resulting losses and potential run lengths.

UTP/CAT extenders are probably a good option in many rental and staging applications, especially as cables are pretty easy and inexpensive to replace and/or have spares. And you can get ruggedized CAT cable if desired.

+1 all stated above. RGBHV is the way to go, you can get bandwidth and resolution way over that of HD resolutions and it is far better than HDMI or DVI alternatives. I usually run 100' of RGBHV before even putting the DA in line. I routinely run over 300' and it looks great. I also use CAT5 converters at times and run 300' no problem. All I run is 720p or 1080p on my productions and people are still amazed that I am using RGBHV and getting an HD signal. I get, "I thought you couldn't get anything of SD on RGBHV" but that is flat out wrong.
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Shane Gavin

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Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #9 on: May 24, 2012, 06:26:46 pm »

+1 all stated above. RGBHV is the way to go, you can get bandwidth and resolution way over that of HD resolutions and it is far better than HDMI or DVI alternatives. I usually run 100' of RGBHV before even putting the DA in line. I routinely run over 300' and it looks great. I also use CAT5 converters at times and run 300' no problem. All I run is 720p or 1080p on my productions and people are still amazed that I am using RGBHV and getting an HD signal. I get, "I thought you couldn't get anything of SD on RGBHV" but that is flat out wrong.

The nice thing though about using DVI over fiber solutions is there is no concern about picking up noise from power lines, so the fiber lines can be run right along with high voltage power.  Additionally, they are much lighter and can be be run further than RGBHV.  Your comments about the benefits of RGBHV bandwidth are still valid and I agree.  Also, with RGBHV, you have the option of connecting via HD/SDI or composite and you have backup lines left over, although digital DA's are needed if you have to boost the HD/SDI signal.
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ProSoundWeb Community

Re: High-Resolution Computer Signals Over Long Cable Runs
« Reply #9 on: May 24, 2012, 06:26:46 pm »


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