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Fiber vs. Copper

Aug 1, 2005 12:00 PM, By Bennett Liles

An industry roundtable examining the two conveyance media.


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Copper vs. Fiber: Glossary

Image courtesy Communications Specialities, www.commspecial.com

Is there actually a conflict between conveyance media? Listening to the traditional rhetoric, one might think that there is a war going on between copper and fiber for world dominance. Both certainly have their proponents, but the truth is that they serve side by side on the same team, each one doing the job it does best. But with new copper transmission technologies and skyrocketing bandwidth needs spurred by HDTV and other modern applications, the roles of copper and fiber are changing.

A team of experts who, by profession, deal heavily with these media sorts through the hype and gets to the facts on what copper and fiber conveyance media are doing and where they are going. The panel: Sam Spennacchio, director of sales and marketing for Fiberplex, Annapolis Junction, Md. (Fiberplex manufactures the LightViper brand of professional audio fiber-optic products); John Lopinto, president and CEO of Communications Specialties (manufacturer of high-performance fiber-optic, scan converter, and video scaler equipment for the professional AV and broadcast industries); Charlie Wicks, CEO/product manager for Pro Co Sound (manufacturer of audio cables and related products for the musical instrument industry and for sound contractors, “plumbers to the audio industry,” according to Wicks); Bill Schuermann, senior project consultant for HFP Acoustical Consultants (provides acoustical consulting services for major industrial, infrastructure, and architectural clients, including audio-visual design); Mark Fehlig, director of engineering for Georgia Public Broadcasting (operates a nine-station PBS network serving Georgia and surrounding areas with radio, television, and satellite-based instructional programming); Dr. John Bryan, vice president for information technology and services for Clayton State University, Morrow, Ga. (currently upgrading its academic office data network consisting of copper and fiber segments to include VoIP and videoconferencing); Ray Legnini, senior marketing product manager for Aviom (provider of distributed audio networking solutions for musicians and audio professionals); and Brent Fowler, technology communications manager for Bellsouth (a Fortune 100 communications company headquartered in Atlanta that offers voice, video, wireless, and data services).

We've heard a lot about relative costs and cost per bandwidth of copper and fiber. Which is actually more expensive?

Fowler: It is clear that we're seeing a reversing trend between copper and fiber. With international growth escalating, the price of materials for raw copper is higher than it's ever been. Meanwhile, the price for fiber cabling is lower than it's ever been. Although we're doing more with copper-based DSL, we do recognize that fiber is the only future-proof technology and are emphasizing investments there. Once you have fiber cable in the ground, upgrades only consist of updating the terminating electronics on each end.

Lopinto: Fiber is really not an expensive medium, especially when you look at the amount of signal that can be transported over a single fiber cable. Fiber costs about the same as Cat-5; however, I can transport many more signals over a single strand of fiber than I can over Cat-5, so there is an advantage there when you look at the system cost.

Bryan: Cost per bandwidth is not the only way of looking at the cost. You also have to look at the total cost of the system. What does it take to put that connection from end to end in place? Right now, the connectors and fiber-optic transceivers are more expensive than the copper transceivers.

Fehlig: Except when there is a very high RF field, such as with transmitter sites. Then the cost of fiber wins hands down for pure noise isolation. Without such an RF field, or known intra-rack, intra-building, or similar hum potentials, I suppose your points are correct. And the budget would steer the course.

Spennacchio: The various fiber connectors can be expensive, but the price of connectors is beginning to get more reasonable. One well-known connector manufacturer I know of that makes a variety of audio connectors is beginning to produce fiber connectors, and the prices are pretty reasonable. Don't forget, the price of a single fiber connector could be $300, but you can have 256 channels of audio on one connector. What would 256 XLR connectors cost? Even 256 Phoenix connectors? What does a big quicklatch or similar multi-pin connector cost? You get the picture.

Schuermann: You are right: Cost is relative. The equipment cost for a fiber system is higher than a copper-based system. However, with a fiber backbone, look at what you are not spending your construction budget on — conduit, labor, copper, and that all-important “risk” issue under a must-work deadline. If you go fiber, your equipment cost is going to be higher because you have to get all of those five to seven signal formats on and off the fiber. However, the savings achieved by this approach makes fiber a very viable option. The other benefit of fiber is that you now have an open architecture for your facility. If the system requirements change, you change the media converter.

Lopinto: As fiber goes, multimode fiber today is more expensive. It is about 10 percent to 20 percent more expensive than single-mode fiber.

How does installing the various media compare? Is it difficult finding or training installers for fiber or Cat-6?

Fowler: What's good about our FTTC solution is that the installation process from the curb to the house is the same for the technician as the copper network. Thus, there is no impact on the installer. We use standard splicing and other cabling techniques. Thus, we do not have to retrain our techs as we move more toward fiber.

Bryan: I have used electrical contractors to pull the network copper and fiber, and then I've used inhouse staff to terminate that because it has been difficult to find contractors to do termination. It is getting easier to find people to do that, but you have to be careful about your relationship with your networking contractor because if they don't do it right, it's a big hassle, and it's very costly to fix.

Lopinto: Fiber is a lot easier to install than coax. As far as terminating it in the field, with the termination kits that are available today, it's as easy to terminate fiber as it is to terminate coax. The advantage is that you need less termination for fiber than for coax because I can send RGB over one single strand of fiber where it would take five coax cables to do it. We do some training regarding how to terminate in the field, but other than that, there isn't much training involved, other than just understanding the terminology. We do full-day seminars around the world that go into the various aspects of fiber, but there isn't that much training that is necessary. The biggest training is for people to get over their fear of fiber, but that is taking place.

Spennacchio: We have discussed various plans on how to help train installers in fiber termination but haven't really come up with a perfect solution yet. You do need to get training to terminate fiber, but it isn't rocket science. It's pretty straightforward, but you do need to learn how to do it. With a lot of installers, the one question they come up with is "OK, so we've got this whole system, and how do I terminate the fiber," and right now my answer is 'find somebody in town that has somebody that knows how to do it and hire them or have them train you."

Schuermann: Terminating fiber does require the integrator to employ or to hire an installer trained and equipped to properly terminate the various terminations, but the savings in man-hours alone will offset the cost of this element as well. The fiber-based systems we design are all splice-free. The only connections on any one fiber are the ends. Splicing is a potential trouble spot.

Wicks: Cat-6 is constructed using an x-separator in the middle to space out the conductors to give us the specifications [crosstalk numbers] needed for Cat-6. It is much larger in diameter than Cat-5e, takes its own special connector [which still fits in an RJ-45 connector], and yes, is more difficult to assemble than Cat-5—a small price to pay for 640 channels, don't you think?

What can go wrong with fiber installations? Are dirt and scratches a problem?

Bryan: You can have backhoe fade when somebody cuts it in the middle. That's why you need to have redundant paths for cabling. Most likely, you're going to have problems at the ends. Dirt, scratches can cause problems. For single-mode fiber, a speck of dirt can almost obstruct the 8mm fiber itself. It's a very small piece of fiber, and so it's very easy for that to happen. If you have your fiber in dirty environments—which is typical in local area networks, in mechanical closets, equipment closets, rooms that are not clean or friendly to fiber technology—it's easy for those things to happen. We have had to occasionally re-connectorize fiber here at Clayton State University.

Spennacchio: We do specify a 3in. bend radius [conservative]. Basically, the only thing you don't want to do with any fiber cable is to conform it to an acute bend radius and then put pressure on the cable. This can break the fibers.

Fowler: Dirt is the biggest problem we encounter that affects transmission performance, but it doesn't always cause scratches. Most of the time, this dirt can be cleaned off without scratches. This problem is relatively easy to remedy.

In the trend toward digital audio onstage, what type of cabling is being used?

Legnini: One of the things that traditional copper is being replaced by is high-density audio over Ethernet-based or Cat-5 based products. There is a lot of that happening. We're finding it more and more. We're seeing a big changeover trend in Europe. It seems to be happening faster there. I think a lot of it has to do with size, weight, and transportation costs. Obviously, fuel is ridiculous there. So there's a pretty good savings when you can take a 300lb. case off the truck and put a 6lb. reel of Cat-5 in its place.

Wicks: The reason for our CAT-alyst digital [twisted-pair] facility-wiring harness had nothing to do with long runs and all the obviously cool things fiber brings to our party. The sole reason CAT-alyst exists is to replace standard analog wiring on performance stages everywhere. Its design allows for the elimination of all conduit under a stage necessary to run the analog wiring through the 60,000ft. to 100,000ft. of Belden 8451 or West Penn 291 or whatever, this conduit having been put there at a cost of $50,000 to $150,000 just for the conduit. This does not help the sound contractor much, but the facility owner is certainly happy not to have to spend the 100 grand for the silly, no longer needed pipe. I'll make what my customers want me to make as a plumber — a rock-solid, inexpensive Cat-5e/6 stage wiring system, not because they welcome the change [from analog], but [because] the change makes their jobs easier, cheaper, faster, and better. Guys that were afraid of RJ-45 connectors are no longer afraid of them, since they are basically fat phone [computer networking] jacks.

Legnini: We've been watching a trend of the pro cable manufacturers coming up with more robust, stage-friendly types of cable — stuff that behaves more like a microphone cable and doesn't roll up and create loops on the stage. It lays flatter, has heavier rubber jacket so that you can walk on it and not feel like you're going to damage the cable. Our products are based on the physical layer of Ethernet with a custom protocol on top. What that means is twofold. One, by stripping off some of the Ethernet stuff that people are familiar with, we get a lot of speed, so that's how we can keep our latency well under a millisecond, and [two], live audio applications is the design protocol. We do away with the TCP/IP junk and a lot of other things, which greatly benefits the audio user. However, the other side of it is that you cannot pass the stuff through a standard computer hub or switch that is waiting for those Ethernet upper layer commands to say, “I've got some data. What do I do with it?” Those devices don't blow up or do anything funny; they just don't pass the data through because they don't know what to do with it. Any kind of passive devices are fine — switch panels, breakout boxes, and that sort of thing. Anything that has a brain in it, that's a no-go.

Any problems with twisted copper pair onstage?

Legnini: We find that people break the tabs off Cat-5 cable, and it's usually from carelessness. You get a tech who thinks that the cable ejects from the jack just by pulling it, and they don't press the tab to unlock it. They just basically rip it off. Those are RJ-45s, but there's a trend to use the Neutrik Ethercon, which is basically an XLR-style jacket, over the Cat-5 end, with all the good components of XLR, the locking and so forth.

Since fiber is optical, you can't put a voltage on it. Isn't this a problem when using wet lines for phantom power and intercoms?

Spennacchio: You are correct that you cannot get voltage down a fiber cable. You can accomplish phantom power and intercom, etc. down fiber. How? Basically, the stagebox or stage headend needs power in a fiber system anyway. You simply send a digital signal down the fiber telling the stage end to “turn on phantom” at the other end. Similarly with intercom, you simply send a signal down the fiber that tells the other end to put out a voltage to “signal” at the other end. It's really pretty simple, but something lots of people would assume is a problem. Pretty cool, huh?

How do copper twisted pair and fiber compare on rejection of RF, EMI, and other noise?

Legnini: The beauty of [digital on copper] is that since you have already converted to data, we're 100 percent certain that you can't get a ground loop in it. So outside interference, as far as the normal audio system bugaboos, is really low. Nobody with a walkie-talkie or other radio junk is going to get in there either. We're just pushing data down a pipe.

Schuermann: The real beauty of a fiber system is the fact that you don't have ground loops.

Fehlig: I'm sure Cat-5, Cat-6, etc. have better common noise immunity than those before it. Fiber beats them all, however. This may particularly be helpful in high-RF [transmitter site] locations. Also, you have the voltage potential ground loops induced by AC power system that may be unbalanced but even for a moment now and then. Fiber ignores that.

Lopinto: An advantage of fiber relative to copper is that it can be installed in far more places than copper can, and by that I mean that you can run it next to power lines and put it in places where if you installed copper, you would have to worry about signal interference and things like that.

Bryan: In higher education, typically we don't have a lot of equipment that generates great amounts of radio frequency, but hospitals for example have tremendous RF interference problems over twisted pair. A CAT scanner or NMR [nuclear magnetic resonance] scanner is not something that you want to have twisted pair around, so typically they use a lot of fiber to the desktop in hospital situations.

How are HDTV and its bandwidth demand going to impact the use of copper and fiber?

Fehlig: We have upgraded our network to pass HDTV from PBS as a compressed ASI feed, which they do. Fox is also ATSC/ASI compressed. That rate [19.38MBps] has no problem with coax systems designed for SMPTE 259 like ours. However, our system here will not pass SMPTE 292 (1.5GBps) over most copper plants.

Bryan: Multichannel HDTV distribution will be a challenge for all systems that use either copper or RF. The bandwidth required for full-resolution 1920×1080 progressive scan HDTV is approximately six times higher than NTSC television, and current CATV and satellite systems use compression to fit hundreds of NTSC channels over coax or via satellite. If you watch movies distributed over CATV or satellite, you have probably seen encoding artifacts from the compression. Full-resolution, multichannel HDTV will require more bandwidth, which only fiber optics can deliver. Fiber optics has at least 100,000 times the bandwidth of copper, and it will be the media of choice for the distribution of multichannel HDTV to the home. This is probably why Verizon has begun upgrading to fiber to the home.

Lopinto: The trend in AV is to create information with increasing amounts of display resolution, and as you continue to go up in resolution, it requires greater and greater bandwidth in order to distribute that information. This plays directly into fiber's strong suit, which is the incredible amount of bandwidth that fiber systems have, counter to the capabilities of copper, whether it be coax or twisted-pair Cat-5.

Spennacchio: The trend is definitely toward fiber for both live sound use [and] installations and broadcast. The advent of all the new digital consoles, mic preamps, etc. has helped to push this issue also. As bandwidth demands continue to increase, the limitations of copper [even Cat-5], begin to surface; we are only scratching the surface of bandwidth capacity with fiber.

Wicks: The fiber guys, after 10 years or so, will win the war. Of that I am sure, but there are many battles to be fought where Cat-5 technology will be inexpensive, reliable, easy to use, and have a good run before the most advanced technology of fiber takes over.

Legnini: Yes, there are all the same good things (with digital on copper) but as people come up with distance issues, that's when Cat-5 stops working for them because it always does have a maximum distance, and fiber then becomes an option.

How are HDTV and its bandwidth demand going to impact the use of copper and fiber?

Spennacchio: We are in development of some products to cost-effectively transport HDVideo on fiber. To transport HDTV signals down fiber takes some very large bandwidth capabilities. This necessitates the need to use single-mode fiber; connectorization would largely stay the same.

Bryan: When we try to run gigabit long distances over copper, that's when we will see lots of interference and signal problems over twisted pair, and I predict that 10Gb Ethernet will kill copper as a networking medium, certainly for the business world in local area networks.

Are there any new transmission technologies that telephone companies might want to use to extend the life of their present coax infrastructure?

Fowler: New technologies like ADSL2+, VDSL2, and copper-pair bonding are increasing the capabilities of copper to deliver higher broadband speeds and lengthening the lifespan of copper loops. However, one thing that is required is short copper loops that are fiber-fed. This represents about 50 percent of BellSouth's network. With short copper loops and new DSL technologies, we're able to do more with the existing fiber we have that will also support customer demands and applications for some time to come. For the foreseeable future, we'll maintain a network that combines both fiber and copper.

So it appears that rising bandwidth demands will soon have fiber ruling computer networks as they expand their mission from 10Mb office applications to 10Gb videoconferencing and HDTV. Within the physical confines of performance venues, digital audio will use twisted pair and fiber, while video will run on fiber to HD displays. For the present and near future, broadcasters and cable outlets will use compression techniques to extend the service of their coax plants and satellite distribution to handle HDTV signals. With a substantial investment in the last mile of copper to the home, telephone companies will use evolving copper-pair transmission technologies to boost the bandwidth they can deliver.

SUMMARY

We thank our experts for their participation in this roundtable session on copper and fiber transmission media, and we hope it has provided some insight on where these technologies are positioned and where they are headed.


Copper vs. Fiber: Glossary

Cat-5: Unshielded twisted-copper pair, traditionally used for Ethernet networks at 10Mbps or 100Mbps.

Cat-5e (enhanced): Suggested for new installations, such as gigabit Ethernet.

Cat-6: Same as Cat-5e, but constructed to a higher standard with more stringent specifications for crosstalk and noise rejection.

Multimode fiber: 62.5-m or 50µm core, LED source light at wavelengths of 850nm and 1300nm. Used for local area networks over relatively short distance.

Single-mode fiber: 9µm core, laser source light at 1300nm and 1550nm. Used for telephone service and CATV for very high bandwidth over long runs.

ADSL2+: ADSL2+ is the successor of the original ADSL standard. ADSL technology has evolved during the last years. Main objects to achieve: more reach and higher bandwidth.

Electromagnetic Compatibility (EMC): The ability of electronic equipment or systems to function in their designated environments without causing or incurring interference due to electromagnetic radiation or induction.

Fiber to the curb (FTTC): A deployment strategy practiced by telephone companies to get the length of their copper loops to the minimum required for high-speed services over copper pair.



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