Immunity to EMI makes copper-fiber cable attractive We marveled at photos of the Titanic taken by the team headed by Dr. Robert Ballard, who located the shipwreck in 1986. But how many of us realized the photos were made possible by a special type of fiber optic cable?
AT&T Inc. and General Growth Properties have agreed to construct a fiber to the premises (FTTP) network to deliver such services as digital TV, high-speed Internet and voice services to a 20,000-home, master-planned community near Houston.
The problem always cited with optical time domain reflectometer (OTDR) measurements, especially on multimode premises cable plants, is they generally do not agree with insertion loss measurements made with a light source and power meter.
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.