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Glossary

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Term Main definition
Digital loop carrier
A carrier system used for pair gain and providing multiple next generation digital services over traditional copper loop in local loop applications.
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Digital signal (DS)
A representation of a digital signal carrier in the TDM hierarchy. Each DS level is made up of multiple 64Kbps channels (generally thought of as the equivalent to a voice channel) known as DS-0 circuits. A DS-1 circuit (1.544Mbps) is made up of 24 individual DS-0 circuits. DS rates are specified by ANSI, CEPT, and the ITU.
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Digital signal cross-connect (DSX)
A piece of equipment that serves as a connection point for a particular digital signal rate. Each DSX equipment piece is rated for the DS circuit it services
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Digital signal processor (DSP)
A device that manipulates or processes data that has been converted from analog to digital form.
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Digital subscriber line (DSL)
A technology for delivering high bandwidth to homes and businesses using standard telephone lines. Though many experts believed that standard copper phone cabling would never be able to support high data rates, local phone companies are deploying equipment that is capable of supporting up to theoretical rates of 8.4Mbps. Typical throughput downstream (from the provider to the customer) are rates from 256Kbps to 1.544Mbps. DSL lines are capable of supporting voice and data simultaneously. There are many types, including HDSL (high bitrate DSL) and VDSL (very high bit-rate DSL).
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Din Plug

DIN - (German standards) Abbreviation for Deutsche Industry Norm

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Diode
A device that allows a current to move in only one direction. Some examples of diodes are light-emitting diodes (LEDs), laser diodes, and photodiodes.
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Diplexor

A combiner unit designed to combine 2G and 3G Tx and Rx signals onto a common feeder /antenna system

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Direct current (DC)
An electric current that flows in one direction and does not reverse direction, unlike alternating current (AC). Direct current also means a current whose polarity never changes.
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Direct frequency modulation
Directly feeding a message into a voltage-controlled oscillator.
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Direct inside wire (DIW)
Twisted-pair wire used inside a building, usually two- or four-pair AWG 26.
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Directional coupler
A device that samples or tests data traveling in one direction only.
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Dispersion
A broadening or spreading of light along the propagation path due to one or more factors within the medium (such as optical fiber) through which the light is traveling. There are three major types of dispersion: modal, material, and waveguide. Modal dispersion is caused by differential optical path lengths in a multimode fiber. Material dispersion is caused by a delay of various wavelengths of light in a waveguide material. Waveguide dispersion is caused by light traveling in both the core and cladding materials in single-mode fibers and interfering with the transmission of the signal in the core. If dispersion becomes too great, individual signal components can overlap one another or degrade the quality of the optical signal. Dispersion is one of the most common factors limiting the amount of data that can be carried in optical fiber and the distance the signal can travel while still being usable; therefore, dispersion is one of the limits on bandwidth on fiber-optic cables. It is also called pulse spreading because dispersion causes a broadening of the input pulses along the length of the fiber.
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Dispersion flattened fiber
A single-mode optical fiber that has a low chromatic dispersion throughout the range between 1300nm and 1600nm.
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Dispersion limited operation
Describes cases where the dispersion of a pulse rather than loss of amplitude limits the distance an optical signal can be carried in the fiber. If this is the case, the receiving system may not be able to receive the signal.
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