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You Can Get There From Here

The challenge for any good signal distribution system is to send a variety of video signals to an equal variety of display devices.

Even though it was open less than a year, Jay-Z's 40/40 Club in Las Vegas was an AV playground. JVN Systems opted for a video distribution solution that utilized Cat-5 wiring and a Magenta Mondo Switch (see sidebar).

Even though it was open less than a year, Jay-Z's 40/40 Club in Las Vegas was an AV playground. JVN Systems opted for a video distribution solution that utilized Cat-5 wiring and a Magenta Mondo Switch (see sidebar).

Credit: Nicholas Foresta

The challenge for any good signal distribution system is to send a variety of video signals to an equal variety of display devices. And to meet the challenge, there's a bewildering array of devices. And while you might regard distribution as a job for installers in malls, casinos, stadiums, and other large venues, it can also be necessary in small educational and corporate settings where flexibility in switching between content sources to one or two display devices–say, a monitor and a projector–is called for.

The question becomes, with all the options at your disposal, with all the permutations of video distribution applications, what system configuration is right from you? More pointedly, what system will get your video signals from point A to points B, C, and D without busting your and your client's budget?

Three main variables that determine a distribution architecture are wiring, the content to be displayed, and the connectors on input and output devices. When you address these variables, basing your decisions on specific questions, it will lead you to the right system.

Category-5 or Something Else?

The first variable, wiring, is probably the most important. When the time comes, you can usually deal with content and I/Os by adding cards and adapters to make almost any content source talk to any display. Understanding how you'll connect your endpoints, though, will determine a lot.

But first you have to ask if you even need video signal distribution. If your only desire is to play a looping video or data display, connecting a DVD player or streaming-video player from a vendor such as Roku directly to a screen might be adequate. You won't have as much flexibility in managing the content, and such devices often have hard drives and other moving parts that can negatively impact reliability. So it's important to ask which displays must be able to show live or frequently varied content, and what your requirements are for image quality and uptime. The answers will drive the decision on which displays can get by with locally stored video.

At distances exceeding 100 feet, the choice of well-heeled or security-conscious customers would normally be fiber-optic cabling, but for cost reasons, most people opt for the unshielded twisted-pair (UTP) copper wiring of Category-5 network cables. Coaxial cable is cheaper still, but at such distances, it might need a peaking amplifier or long-distance line driver to maintain signal strength.

Paul Hand, product manager for AMX's AutoPatch group, says most installations covering shorter distances use coax because of its track record in AV, but economics and improved technology make Cat-5 the choice for nearly anything but the smallest video distribution systems.

"[Coax] is so much more cost-effective and so proven. It's been used forever and people know how to deal with it," Hand says. "Cat-5 is a cruddy way of sending high-resolution video. It's a poor medium. But the industry has come up with great devices–the transmitters and receivers–to overcome that."

With Cat-5, the idea is to use a building's existing data wiring, or if new cabling is unavoidable, to have it be the cheapest possible. Special equipment is required to convert AV signals for transmission over UTP. Near the video source is a transmitter, and at the other end of the wire, a receiver, typically one per display, though some are dual-display. Sometimes a distribution hub is needed to replicate and transmit signals to additional devices.

Performance can certainly be comparable to coax, and because of its smaller circumference, UTP can be easier to thread through conduit and might be a better option in older buildings, which might lack conduits and have few places to conceal coax. UTP terminates in a common RJ45 connector.

Still, when considering wiring, be aware of Cat-5's other characteristics. Especially at long distances, twisted-pair cable is prone to skew: variations in the lengths of each pair of wires that can cause a horizontal misalignment in the red, green, and blue colors on the screen, compromising image quality. There are devices designed to compensate, but many support fixed lengths. Pick the wrong length, and you might have to add more such devices at greater expense than if you had picked longer, or variable, lengths in the first place.



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