6 Reasons To Use Fiber On Your Next Project
Connecting the right cable in the right place is obviously essential for pro AV systems integrators, but choosing the right type of cabling for the job can be just as important. We've all heard the stereotypes, as the fiber versus copper debate has been raging for more than a decade.
“With fiber, run it with the power cable — it just doesn't matter,” Commare says. “Where you run it doesn't become an issue unless you put it somewhere where a door can slam on it.”
Fiber can even be run in the same conduit with a low-voltage electrical line. For instance, Caidar notes, the wires carrying power for a projector bulb can be packaged with the fiber carrying the video signal to that projector, making for simpler installation without causing any crosstalk problems. In many parts of the United States, fiber can also be run without conduit, simplifying installation and reducing cost. (Check with local codes for specific conduit requirements in your area.)
This immunity to interference, coupled with fiber's ability to carry signals greater distances without loss of quality, means more consistent results, maintains Lopinto. With copper connections, he says, “you may have 10 plasmas all showing the same image, but they all look different.”
Interference and distance from the source may affect brightness, color balance, and clarity. With fiber, “you get absolute consistency from one display to the next, regardless of what the length is back to the source,” he says.
But Al Keltz, general manager of Whirlwind, adds a qualifier to this. While analog signals over copper wire are highly vulnerable to interference, Keltz says, digital signals are less so, even when transmitted over copper. Keltz says he wouldn't run any copper AV cabling parallel to electrical cables for any distance, but other than that few environmental factors would have much effect on a digital signal.5 Fiber doesn't radiate signals like copper cable.
“Fiber cable, because it's not electrical, doesn't act like an antenna and radiate a signal,” Lopinto says. That makes fiber communications more secure than transmissions over copper cabling. “It's very hard to tap into fiber-optic cable,” Caidar says. “It's very easy to tap into coax and very easy to tap into twisted pair.”
Does this security matter in AV applications? Not always. If you're carrying audio signals from a stage to a mixer, or a video image of a conference speaker on stage from a camera to a projector that will display a large image on a screen above the speaker's head, you're not dealing in sensitive information. But consider video from surveillance cameras being transmitted back to a bank of monitors or a private videoconference. Caidar says fiber is especially popular in government and military installations for this reason.
The fact that fiber doesn't radiate a signal can be important for another reason — running fiber alongside copper cabling won't be subject to interference from the adjoining copper; nor will it cause any interference on the nearby cable. This could also be important where fiber runs close to sensitive electronics, such as in a hospital, suggests Barlow.6 Fiber doesn't cost as much as you think.
In bulk, fiber costs about eight cents a foot. Cat5 twisted-pair cable costs about five cents a foot. The copper cable is cheaper — but fiber has greater capacity. Therefore, it can be cheaper when bandwidth requirements are high.
The bills for fiber start mounting when you look at the supporting electronics, which to date have cost more than their counterparts for copper. But that cost is coming down. The need to convert signals from electronic to optical is even being eliminated in some cases. In fact, some manufacturers have begun including optical outputs in video cameras, Hall says. And in longer-distance installations, the need for more switches or repeaters to enable copper to go the distance can make fiber the cheaper alternative.