The optical time domain reflectometer (OTDR) has been an important tool for fiber optic testing and troubleshooting since its invention 25 years ago. We have discussed this several times in this column and in other Electrical Contractor articles, so I hope you are already familiar with them.
Industry standards make the world go ’round. No kidding. Without standards, communications and networking would never work. Telephones allow you to talk to anyone in the world, assuming you speak their language. Standards are the “language” of networks and communications.
Those involved in fiber optics are incurable optimists. Market forecasts always show upward trends and promise that fiber is going to replace copper wire or rebuff wireless and whatever other alternative methods of communications are currently being hyped.
Optical fiber, like copper wire for communications, needs to be kept dry to maintain its performance. On wire, moisture causes high impedance and crosstalk. In fiber, it adds to the attenuation and may make fibers brittle and more susceptible to damage.
Many fiber optic specifications and tests refer to wavelength because most parameters have some wavelength dependency. Attenuation, for example, is caused by absorption and scattering. Absorption occurs at certain wavelengths and scattering gets less significant at longer wavelengths.
Imagine what would happen if you were working on a construction project and had to make a measurement. You used your tape measure and got a length based on the markings on the tape. A member of your crew showed up with a laser ranger and made his measurement.
Some years back, fiber optic connector manufacturers started offering connectors that terminated fiber quickly without using adhesives or requiring polishing. The manufacturer glued a short stub fiber into the connector ferrule and polished it perfectly in the factory.
It is common knowledge that fiber optics has much more information-carrying capacity than copper wiring, mostly due to the fact that fiber optic suppliers have been touting the bandwidth advantages of fiber for so long.
A few years ago, a cohort and I were demonstrating fiber optic terminations in our booth at the NECA show. He came back from visiting another booth with a large twist-on wire connector, commonly called a “Wire-Nut,” the Ideal trademark for these devices.
Fiber optics, like many of today's technologies, has developed its own language, created from technical terms specific to fiber optic technology. Sometimes the fiber optic community cannot-or will not-standardize, and we mean beyond choosing a standard connector.
Every fiber in an installed fiber optic cable needs testing for loss. The insertion loss test is the standard test required by every network and cabling standard around the world. Superficially, loss testing is easy.
Since the beginning of fiber optics, groups such as the Telecommunications Industry Association (TIA) have worked to create standards. Standards are mandatory for technologies to move from R&D to large-scale commercial applications.
Contractors and installers generally are concerned with cabling, not networks. Installing and testing cabling to standards such as TIA-568 is the heart of their voice/data/video work. Cabling standards writers are primarily concerned with performance and interoperability.
Since the first installations of fiber optic networks more than 25 years ago, the goal of the fiber optic industry has been to install fiber optics all the way to the home. From an economic standpoint, fiber was most cost-effective in the long-distance networks.