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Cat5/6 or Coax for extended video?

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Scott Raymond:

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

Thomas Lamb:
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.

Brad Weber:
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.

Jonathan Johnson:
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.

Brad Weber:

--- Quote from: Jonathan Johnson on January 16, 2011, 09:24:43 pm ---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.
--- End quote ---
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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