AV’s Low-Fibre Diet

Fibre is a viable alternative to copper. So why aren’t more AV pros using it? Tim Kridel investigates...

Just about every major city in Asia has spent the past decade sprouting bumper crops of skyscrapers. All of that construction has increased demand for materials such as copper, which doubled in price between 2005 and 2006.

That cost increase is one of several reasons why fibre optics is starting to become an attractive alternative to copper-based technologies in the AV industry.

“Today, with requirements for high-resolution video transport over longer distances, fibre has become the only choice,” says Jim Jachetta, senior vice president for sales and marketing at MultiDyne Video & Fibre Optic Systems. “Copper cable has bandwidth and distance limitations. Also, the cost of copper has skyrocketed over the last few years, while the cost of fibre has come down.”

Another driver is the growing use of technologies such as Digital Visual Interface (DVI).

“Signal formats such as DVI can only reach 30 feet over copper,” Jachetta says. “If a customer needs to move DVI more than 30 feet, fibre is the only choice.”

AV manufacturers are responding to those needs and trends by offering more fibre-ready products. The more such products on the market, the more AV integrators perceive fibre as a viable option.

“There’s more exposure to fibre optic products and technologies in the marketplace,” says John Lopinto, president and CEO of Communications Specialties, an equipment vendor that also offers educational workshops on fibre. “In the past year, you’ve had companies like Extron and Magenta introduce their first fibre optic products. I think that’s raised the overall awareness.”

Another driver is the bandwidth requirements of technologies such as high-def.

“With demand for more resolution, fibre has become the medium of choice,” Jachetta says.

Or at least that’s the trend that should be playing out. Some vendors say AV integrator interest in fibre is still nascent, at best, with slower adoption in Europe.

“We’re seeing more people inquiring about it and taking a look at it, but I’m not sure if there are more and different people using it,” Lopinto says. “In Europe, it seems to be in a relatively static state. It’s tough enough to get AV integrators to feel comfortable with fibre optic technology. In Europe, it’s even more so. I think there are more people kicking the tires than implementing it.”

The view is similar from the Munich office of Corning Cable Systems, a major fibre manufacturer.

“There's only a small portion of dedicated audio and video networks based on fibre in Europe,” says Helmar Krupp, product group manager for splice and test equipment for the EMEA, APAC and China markets. “Most are still coaxial broadband, xDSL or satellite.”

Fibre adoption in AV outside of Europe is worth noting because the more places it’s used, the bigger the worldwide market it is, which produces a wider selection of products and fosters competition that helps drive down costs for both manufacturers and their customers.

“We have also seen growth in these markets in Europe, Asia and Latin America,” says Jachetta, whose company is seeing significant growth in fibre in its core market of North America. “Quite often a lower tier or third-world market will leap-frog technology. In these cases, there is no existing infrastructure to limit new technology.”

Modus operandi

Like alternatives such as coax, fibre is available in a variety of types. The two major ones are single-mode (sometimes called “mono-mode”) and multi-mode. As its name implies, single-mode fibre transports all of the AV packets on a single beam of light, while multi-mode carries multiple beams in parallel.

This difference affects both the overall system cost and choice of fibre type. Multi-mode fibre generally is used for links no longer than about 16 KM because the light signals start to scatter as the distance gets longer. Single-mode fibre generally is used for longer links, but it requires signal transmitters – called optical emitters – that are at least twice as expensive as the ones used with multi-mode fibre.

“Single-mode has almost infinite bandwidth and can reach 20KM with generic equipment,” Jachetta says. “With multi-mode, you actually run out of bandwidth before light.”
Multi-mode fibre has what’s known as a “bandwidth-length product” of about 500 MHz per kilometer.
“This means a 500 MHz signal can reach 1 KM,” Jachetta says. “If we want to transport a 1.5 Gbps HD-SDI signal, the maximum distance supported would be 500MHz*KM / 1500MHz = 0.333 KM or 333 Meters.”

Calculating fibre’s business case

For AV integrators that are using fibre, one part of the appeal is the cost savings.

“The fibre itself – the raw cable – is actually the cheapest medium you can buy,” Lopinto says. In the United States, it’s priced about the same as Cat5, so it’s cheaper than Cat6 and than even a single strand of coax, let alone five of them.”

But those savings can be eaten up by other factors, such as any premium for the fibre-ready AV gear that sits on the ends of the cheap lines. Whether those premiums are themselves cancelled out depends on the type of installation.

“When you look at the total system cost – the boxes, the cable and the cost of installation – in many cases, it’s more expensive than what you can accomplish with copper,” Lopinto says. “On the other hand, it’s not as expensive as you think when you start to get into more complex installations where you’re trying to communicate many signals from a point to multipoint. That’s what people have to understand. When you start to get more complex, or systems that involve more cable length, then the [cost-benefit] crossover starts to occur.”

But cables and equipment are just two parts of the equation that determines overall cost – and the business case for using fibre. Another key factor is labor, which is where fibre often has an edge. For example, fibre often provides more installation flexibility because it doesn’t emit electrical signals and isn’t susceptible to interference, such as electrical noise from fluorescent light ballasts. As a result, the fibre can be run alongside power cables or coax carrying other AV signals, or even snaked through existing conduits. By comparison, copper technologies might have to take a longer, circuitous route to avoid interference, potentially increasing labor costs in the process.

Even so, pulling fibre isn’t free. As a result, it often can make sense to pull more strands per cable than the installation initially requires because the material itself is relatively inexpensive – a common practice in the telecom industry. (The fallow fibre often is called “dark” fibre because it’s not “lit” with a signal.)

“You want room for growth and expansion,” Jachetta says. “In most cases, the labor to pull the fibre is more than the fibre itself, so specify a fibre cable with extra strands. Even if you are transporting low-bandwidth signal today, always pull single-mode fibre to future-proof your fibre design. This way, you will be ready for HD, DVI, HDMI or a high-bandwidth standard that is yet to come.”

Fibre has greater bandwidth than copper alternatives, so it can carry more traffic than, for example, multiple coax cables. That ability can translate into labor savings if the installation requires union labor that charges a fee for each cable pulled, as is the case in many cities. So with a single fibre line doing the work of five coax cables, the labor savings could be 5:1.

Fibre sometimes also can reduce troubleshooting costs. For example, suppose that a commercial building’s AV system is designed before construction begins, with some of the cabling planned to be routed through elevator shafts. When the elevator motors are installed, it turns out that they create more electrical noise than expected. If copper cable had been installed, that noise could force an expensive, last-minute reengineering of some of the AV infrastructure. But that wouldn’t be the case with fibre because it’s immune to electrical noise. So in that type of scenario, fibre could save money in troubleshooting and reengineering.

Getting into the game

Fibre optic cables and equipment are widely used in other industries, particularly telecom. That adoption helps improve the business case for using the technology in pro AV.

“Fibre optic technologies are being used in many different industries today, which globally increases the demand for tooling and test equipment,” says Lee Dodson, vice president of marketing for Extron. “This allows for higher availability of materials at prices that are more affordable to A/V integrators. Also, as a byproduct of the demand, many new connector solutions are being introduced that significantly reduce the time and efforts required to terminate fibre optic cabling.”

For AV pros, the cost of expanding into fibre isn’t prohibitively expensive: less than €3000. Here’s a rundown of the basic tools required:

-A handheld fibre optic power meter. This device measures the presence of a signal at different points along a strand of fibre. Like a continuity meter in the copper world, it can be used for troubleshooting tasks such as pinpointing the location of fibre break. Cost: less than €400.

- A field termination kit. Besides putting connectors on fibre, these kits also can be used to join two pieces of fibre, such as when repairing a break. “It takes about 5 minutes to put a connector onto a piece of fibre,” Lopinto says. “Unlike the old systems, it doesn’t require any epoxy or grinding or fusion. It’s a straight mechanical process. It gives you an excellent splice with very little loss.” Jachetta agrees: “Quick-connect, epoxy-less connectors are as easy to terminate as a coaxial BNC.” Cost: about €1100 for the kit, plus about €18 per connector.

- A calibrated light source. In venues that already have fibre, this tool is handy for determining whether those lines can handle AV applications. The light source also can be used in conjunction with the power meter to identify loss in a fibre optic line. Cost: about €1100.

The total for basic gear comes to about €2600, which may be reasonable for an integrator that sees enough opportunity in fibre.

“People spend that much and more in coax tools or signal generators for Cat5,” Lopinto says. “If you’re going to get into fibre, it’s a small price to pay.”

It’s also a price that more AV integrators may have to pay: As fibre becomes more common in commercial buildings, it becomes tougher to avoid.

Says Extron’s Dodson: “A/V pros don’t always have the luxury of dictating which cables are to be used, especially in installations already pre-wired.”

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