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Author Topic: Cat5/6 or Coax for extended video?  (Read 8118 times)

Scott Raymond

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Cat5/6 or Coax for extended video?
« on: January 12, 2011, 05:19:38 pm »


Just looking for thoughts on what direction video runs are going.  We are looking to upgrade a room and install new into another couple rooms.  Now we are just doing a basic single coax run out of a VCR to feed TV monitors in a couple rooms with mediocre results.  I've done some studying and searching on baluns for all sorts of conversions using cat5/6.  Even a suggestion to just run multiple coax for RGB/sync or component video as it ends up costing the same as using good baluns and cat5/6 and can have less issues.

At least two rooms will be fed for video projection and  a couple for smaller panel type displays.  We will be doing this ourselves so labor won't come into play in the decision.  I'm just looking into thoughts on what the trends are in video.  Will component or RGB be around for a while yet or is everything heading the DVI / HDMI for installs like this.  We aren't at the professional camera stage yet just using mini DV.

Thanks for any thoughts!

Scott
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Thomas Lamb

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Re: Cat5/6 or Coax for extended video?
« Reply #1 on: January 12, 2011, 11:41:59 pm »

Call me old school but I got burnt once with baluns (I still have the scars) so I am anti!! The new facility I am at has some and has had issue with them. so this week we ran some rgbhv to a few select locations for dependability sake. I still use rgbhv extensively in installs with flat panels along with a strand or two of mic cable. That way I have stereo or two channels of audio and VGA or component. If you run the proper grade at a later date you could even use it for HD/SDI.
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Brad Weber

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Re: Cat5/6 or Coax for extended video?
« Reply #2 on: January 13, 2011, 08:08:18 am »

It may depend on what you are, and what you may be, distributing in terms of source and content.  The 'analog sunset' has started to kick in where analog outputs on Blu-Ray players are limited to SD (480i/576i) resolution and in three years there will be no analog outputs from Blu-Ray players.  However, that applies to AACS encrypted content and Blu-Ray players, so basically commercial Blu-Ray releases, and would not necessarily affect internal or non-commercial content (although the Blu-Ray player manufacturers may elect to do so).  So if you may want to distribute commercial Blu-Ray content now or in the future this could be an important factor.

A similar issue exists with computers as while computers and laptops with VGA outputs are still common, there are an increasing number coming with only DVI, HDMI or DisplayPort outputs.  I don't know if you'd ever have a computer source but again, something to consider.


I have worked on several large audio and video over UTP systems with good results, but I tend to specify higher end active products such as those from Extron, FSR and Magenta Research.  I also tend to be conservative in interpreting the "up to X distance at Y x Z resolution" specs, keeping in mind that those are maximums.


I was not clear on one point.  Is the intent to add to or supplement the existing RF coax based distribution or is the intent to replace that?  That could affect what makes the most sense.

I would also say that labor could affect the approach.  Regardless of whether coax, UTP, bundled RGBHV or component, installing distribution systems such as noted with the potential of having to use in-wall or plenum rated cable for some of the runs typically means using bulk cable and terminating it yourself.  If you have someone with experience and the toools to terminate specific cables that could be a factor in the decisions.  For example, having to purchase BNCs and the appropriate stripper, crimpers and dies for the specific cable being used could make bundled RGBHV a more expensive option than if someone already had those for the cable planned.
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Jonathan Johnson

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Re: Cat5/6 or Coax for extended video?
« Reply #3 on: January 16, 2011, 09:24:43 pm »

We are still in the transition period from analog to digital. What you install today might not be compatible with what you'll need ten years from now.

One of the problems with digital signals (HDMI, DVI, DisplayPort) is that the specifications for these signals allow for only relatively short runs: the practical limit without doing some kind of balun or conversion seems to be around 50 feet. (The HDMI specs don't give an absolute distance; rather, they specify that the signal cannot be degraded below a specified value.) Analog lines typically can be run much longer, not because the signal is degraded less, but because an analog signal is still usable when significantly degraded. Digital, on the other hand, becomes unusable at the point where the ones and zeroes cannot be clearly resolved enough to provide a reliable data stream.

Baluns may be useful, but as others have pointed out, they are not always the best solution. If they were, we'd be connecting our VCRs to our TVs with CAT5e cables. To split the signal to multiple displays requires special equipment.

If you can convert the digital signal to RF (digital broadcast), you should be able to make much longer runs. Essentially, you are converting a digital signal to an analog one, encoding via an RF Modulator. The RF signal can be transmitted along a single, inexpensive coax cable (which you may already have in place) to the receiver, usually a TV which already has a tuner built in. The signal is easily split to multiple displays using inexpensive splitters. The disadvantage is that an HD RF Modulator can be quite expensive. If you are using an HD video mixer, it already outputs a signal an HD RF Modulator can use. My guess is that this is probably the most future-proof solution, as digital broadcast is here to stay for a long time.

Another possibility -- and I've done no research on this -- is using fiber optics. This allows extremely long runs, but the fiber and equipment required can be very expensive.
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Brad Weber

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Re: Cat5/6 or Coax for extended video?
« Reply #4 on: January 17, 2011, 08:57:54 am »

If you can convert the digital signal to RF (digital broadcast), you should be able to make much longer runs. Essentially, you are converting a digital signal to an analog one, encoding via an RF Modulator. The RF signal can be transmitted along a single, inexpensive coax cable (which you may already have in place) to the receiver, usually a TV which already has a tuner built in. The signal is easily split to multiple displays using inexpensive splitters. The disadvantage is that an HD RF Modulator can be quite expensive. If you are using an HD video mixer, it already outputs a signal an HD RF Modulator can use. My guess is that this is probably the most future-proof solution, as digital broadcast is here to stay for a long time.
A couple of things to add to this.  One is that you would want to make sure all the display devices have ATSC tuners.  Televisions made in the last year or two typically do but older televisions may have NTSC tuners while monitors and projectors generally have no tuner.  Those devices without integrated ATSC tuners would require external tuners.  The other is that while many existing analog NTSC RF distribution systems may be able to distribute HD digital signals, in some cases the bandwidth and losses of taps, splitters and the cable used in the existing system may not be compatible with HD ATSC signal  distribution.
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Arnold B. Krueger

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Re: Cat5/6 or Coax for extended video?
« Reply #5 on: January 20, 2011, 09:03:05 am »


Baluns may be useful, but as others have pointed out, they are not always the best solution. If they were, we'd be connecting our VCRs to our TVs with CAT5e cables. To split the signal to multiple displays requires special equipment.

This is a funny comment since the essence of HDMI is doing almost exactly what you say never happens. 

If you've got a source (e.g. Blu Ray player) and a display with HDMI connections, this is almost always the best and easiest way to hook the two together.

On paper HDMI over long lines with active repeaters or high powered drivers should give the most perfect results since everything stays in the digital domain.
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Doug Fowler

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Re: Cat5/6 or Coax for extended video?
« Reply #6 on: January 20, 2011, 12:05:35 pm »

This is a funny comment since the essence of HDMI is doing almost exactly what you say never happens. 

If you've got a source (e.g. Blu Ray player) and a display with HDMI connections, this is almost always the best and easiest way to hook the two together.

On paper HDMI over long lines with active repeaters or high powered drivers should give the most perfect results since everything stays in the digital domain.

Please go to your profile and put your full name in the "Name" field.

Thank you.

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Brad Weber

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Re: Cat5/6 or Coax for extended video?
« Reply #7 on: January 20, 2011, 04:14:41 pm »

If you've got a source (e.g. Blu Ray player) and a display with HDMI connections, this is almost always the best and easiest way to hook the two together.
A source to a single display a limited distance away is indeed what HDMI most directly addresses.  That works well for most residential and consumer applications, the problem is that many pro AV applications involve multiple sources to multiple, and varying, destinations with longer distances between devices being common.

On paper HDMI over long lines with active repeaters or high powered drivers should give the most perfect results since everything stays in the digital domain.
The signal being digital does not guarantee a 'perfect' result.  Analog signals tend to be affected by line losses, noise, etc. to varying degrees while digital signals tend to either not be affected or be very affected.

It seems that what potential capabilities of HDMI you are trying to implement affects the cable with four current HDMI cable types defined that are typically applicable to Pro AV:
  • Standard HDMI Cable
  • Standard HDMI Cable with Ethernet
  • High Speed HDMI Cable
  • High Speed HDMI Cable with Ethernet
So it's easy to see that the cable can affect what capabilities are supported, for example a "Standard HDMI Cable" is supposed to be tested for 720p and 1080i signals but not for 1080p or Deep Color signals, which are part of the "High Speed HDMI Cable" rating.  Try sending a 1080p signal over a "Standard HDMI Cable" and it may work fine or may not work at all.

I also have to wonder if support for higher bandwidth signals, return audio and Ethernet may also impact any intermediate devices.  And HDCP becomes a factor with HDMI repeaters, drivers, etc.  Looking quickly at some such devices the product data seems to rarely address such factors, making a 'perfect' result a far from assured outcome.
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Scott Raymond

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Re: Cat5/6 or Coax for extended video?
« Reply #8 on: January 28, 2011, 08:07:05 pm »


Thanks for all the info, suggestions and discussion!  I've been browsing, studying and ruminating on all the different hardware and ideas.  The vast amount of gear available is slightly staggering.  And I just basically looked through Extron and Magenta and one other company's product.  I now at least have a semi-educated idea of what it's going to take to implement a system depending on what goals and cost they want to achieve.  Other than staying with just basic video the solutions are all going to be fairly expensive to get into.  What comes about will likely depend on how important they see the need to upgrade or look down the road a bit for what we may be doing or needing then. 

Just FWIW we are in construction on stage one of a proposed 3 stage expansion.  This stage is an addition of space for a new nursery and conference room, moving and revamping the youth ministry as well as opening up the current entryway and upgrading the whole building with sprinklers.  So new video will be needed in the nursery and conference room in the addition, as well as possibly having video in the enlarged entry.  The other areas are an existing room that's had video and a gym/multipurpose room that might get a feed for overflow or miscellaneous use.  Those involve distances up to around 250 ft. whereas the others are all under 50 ft.  So we aren't talking huge distances at this stage but the second and third phases will involve a separate youth wing and then a new worship center and longer distances involved.  At this point it may boil down to cost and whether they feel the need for any type of digital signage for announcements or messaging etc.  I've seen text over composite from an older computer I have and it definitely "ain't pretty".

Looking at the Magenta hardware I came up with a rough estimate of 1300/1500 dollars for 4 or 5 locations and then whatever Cat5/6 costs would end up at.  With the longer runs it sounds like it might be good to use low skew cable even though it might not be absolutely required at that distance.  Running discrete coax could easily get up in the same area with splitters or matrices involved with that.  The other idea brought up with HD rf was one that hadn't occurred to  me even though we're currently using old analog RF.  Doing a search I ran across an intriguing fairly new product from a company by the name of ZeeVee.  Some of you may have looked into them, they have modulators from around 900$ to maybe around 1800$.  If they are a reliable, quality product they would allow a fairly large distributable system built on standard single rf coax using pretty much off the shelf splitters etc.  They use QAM channels so any off the shelf consumer flatpanel (cable capable obviously) could be used at the receiving end.  Adding another unit and a simple combiner some where down the road would be easy and allow sending different program material to any location.  Seems like a viable option for a ways down the road but I'll welcome any thoughts anyone has on something like this.  Here's the link for anyone that hasn't run across them yet.

http://www.zeevee.com

Thanks again!

Scott
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Kevin Hoober

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« Reply #9 on: January 28, 2011, 09:19:22 pm »

Scott,

I recently implemented a digital CATV distribution setup for a new campus.  I was originally looking at the ZeeVee product, but was steered away from that product by some smart folks.  I came across (and was recommended to) Contemporary Research's QMOD-HD boxes--I have 3 (2X HD, 1X HDSDI).  They work great...and look good--I highly recommend them. 

Kevin
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