You’re reading an outdated article. Please go to the recent issues to find up-to-date content.
There are many instances where converting from copper to fiber is necessary or more cost-effective. Sometimes it’s done just to showcase new technology. But whatever the reason, making the conversion has become simple and inexpensive.
Converting to fiber is sometimes the only technical solution. If you are dealing with an environment that has lots of electromagnetic interference (EMI)—such as around heavy machinery, welders, big motors, motor controls, or very high voltage—any copper wiring, even the best enhanced Category 5 or Category 6 will pick up enough interference to prevent data transfer with low error rates. Fiber is totally dielectric, so it has no EMI pickup. In fact, most high-voltage power transmission lines have fiber optics running down the middle of them.
Category 5e or Category 6 is only designed to run 100 meters (330 feet), but runs between buildings or in large plants that may greatly exceed that limit. Coax used in closed-circuit television (CCTV) systems can usually only run 300 meters (about 1,000 feet). Longer copper links require expensive repeaters and lose signal integrity. Fiber links up to 100 megabits per second are usually specified for lengths of 2 km (6,600 feet) to hundreds of kilometers. Gigabit links may be specified for shorter distances, typically 250 to 550 meters (about 800 to 1,600 feet), but that’s still much longer than copper. Campus networks, large industrial plants, and sprawling facilities such as airports use lots of fiber to connect widely spaced areas.
Security is important to the government and military, and fiber provides it, because it is very hard to jam or tap. Information sent over fiber is generally secure without encryption. Since it requires no repeaters, it is much more reliable than copper. It emits no detectable signals, so it does not give any indication of its existence or location. All of these important security issues lead practically every military or government agency to use fiber.
Fiber can be the most economic choice for simple premises networks, too. As we discussed in April and May of last year, an all-fiber network does not need traditional telecommunications closets, with their costs for space, power grounds, and air conditioning. A properly designed all-fiber network can be more cost-effective than the usual backbone/horizontal cabling model used with copper.
Whether using fiber is a technical necessity or a proven cost saver, you must convert the network equipment to fiber optics. Most PCs are available with an Ethernet connection of 10 or 100 Mbps using Category 5 cabling but can be adapted to fiber with a plug-in network interface card. Low-cost hubs are designed for Category 5. High-end hubs, switches, and routers offer either copper or fiber connections, but fiber connections cost much more than copper.
Often, it is best to convert from Category 5 to fiber using “media converters.” There are many varieties to choose from, depending on the network type, link speed, and distance requirements. Most are digital for data networks, but analog links are available for transmitting data that is in an analog voltage or current format. CCTV and cable access television (CATV) links are mostly analog.
Media converters are simply “black boxes” that have inputs and outputs for one type of cable and inputs on one side and outputs for another type of cable on the other side. Inside the box is electronics that converts from one type to another and regenerates the signal at the proper levels for retransmission. They match connector styles, cable types, and signal levels to ensure perfect compatibility on each side with the proper cabling. Converters that are duplex, like most networks and CCTV with pan/tilt controls will use two fibers, one transmitting in each direction for simultaneous operation in both directions. Most run on wall-mounted AC adapters, although some are powered from data busses or even PC keyboards.
Choosing media converters is easy. Specify what kind of link you are converting and how far you need to go. Manufacturers offer media converters in many different varieties, to cover almost any application. Some converters even offer several data formats in one converter by multiplexing. You can get some that provide data lines and plain old telephone service (POTS) in the same unit.
These devices require purely “plug and play” installation. You need to have installed the proper fiber optic cable beforehand and tested it for proper loss. The converter should be plugged into the uninterruptable power supply of the PC, hub, or other equipment to ensure no signal is lost in case of power failure. The copper cable and the fiber cables are plugged in on either end, and the link should be operational.
Prices for 10Base-T, 100Base-T, and CCTV converters begin at $100, increasing as more features or longer length capability are added. Fiber optic cable is inexpensive and connectors are reasonably priced. So, if you find yourself in one of the situations mentioned above, don’t worry, it’s easy to convert from copper to fiber. EC
HAYES is the founder of Fotec, the fiber optic test equipment company and Cable U training. Find him at www.JimHayes.com.