Glossary

A chemical added to plastics to make them softer and more flexible.

The air-handling space between the walls, under structural floors, and above drop ceilings when used to circulate and otherwise handle air in a building. Plenum-grade cable can be run through these spaces if local building codes permit it.

Cable whose flammability and smoke characteristics allow it to be routed in plenum spaces without being enclosed in a conduit; all cables with this rating must pass NFPA 262 (formerly UL 910).

The male component of a plug/jack connector system. In premises cabling, a plug provides the means for a user to connect communications equipment to the communications outlet.

One of three basic methods of adding information to a sine wave signal in which its phase is varied to impose information on it. See also amplitude modulation and frequency modulation.

Carrying a signal between two endpoints without branching to other points.

Identifies which side of an electrical circuit is positive and which is negative.

(1) Alignment of the electric and magnetic fields that make up an electromagnetic wave. Normally refers to the electric field. If all light waves have the same alignment, the light is polarized. (2) The direction of vibration of the photons in the light wave.

Optical fiber that maintains the polarization of light that enters it.

Spreading of the light wave caused by imperfections in a single-mode optical fiber that slow down a polarization mode of the signal. When one polarization mode lags behind another, the signal spreads out and can become distorted.

The degree of variation in insertion loss as the polarization state of the input light is varied.

A media access control method that uses a central device called a controller, which polls each device in turn and asks if it has data to transmit. 100VG-AnyLAN hubs poll nodes to see if they have data to transmit.

A type of synthetic rubber often blended with other synthetic rubbers to improve their dielectric properties.

A polymer that is used to coat optical fiber for harsh environment applications.

A substance made of repeating chemical units or molecules. The term is often used as a synonym for plastic, rubber, or elastomer.