Components

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GLOSSARY
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Glossary
Copper / Fiber Glossary of Terms
Power Sum: The method of evaluating the
performance of a single cable pair taking into
account the impact of other cable pairs operating
simultaneously.
Propagation Delay: The time loss due to the
transmission medium between when a signal is
transmitted and when it is received.
PS-ACR (Power Sum Attenuation to Crosstalk
Ratio): Similar to ACR except Power Sum Near-end
crosstalk is used in the calculation instead of near-
end crosstalk. Used to quantify the noise seen at
the receiver due to multiple near-end transmitters
relative to the attenuated transmit signal present at
the receiver. Usually expressed in decibels (dB).
PS-ELFEXT (Power Sum Equal Level Far-end
crosstalk): The mathematical summation of the
equal level far-end crosstalk power relative to the
attenuated signal of the disturbing pair, coupled into
a disturbed pair from all other pairs within a cable or
transmission channel. Usually expressed in decibels
(dB). Used to quantify the noise seen at the receiver
due to multiple far-end transmitters.
PS-NEXT (Power Sum Near End Crosstalk):
The measurement of the total crosstalk energy in the
cable when more than one cable pair is operating
simultaneously. It is determined by measuring the
crosstalk of each of the pair combinations in the
cable.
PSTN (Public Switched Telephone Network):
The worldwide communications network that
carries phone calls and data.
RBOC (Regional Bell Operating Company): The
regional holding companies that resulted from the
divestiture of AT&T. The original 22 Bell Telephone
companies were combined into seven regional
companies in 1984.
Resistance: That property of a conductor, wire or
shield that determines the current flow for a given
applied voltage. In DC circuits, the opposition a
material offers to current flow, measured in Ohms.
In AC circuits, resistance is the real component
of impedance and may be higher than the value
measured at DC.
Return Loss (RL): Also known as echo. Ratio of
the reflected power in a cable or transmission
channel to the incident power. Effectively expresses
therelationship of impedance changes throughout
a cable or transmission channel, as a function of
frequency, relative to the normal system impedance.
Used to quantify the noise seen at a receiver due
to reflections (echo) from a near-end transmitter
on the same pair when full duplex, bi-directional
transmission is employed. Usually expressed in
decibels (dB).
Riser: Pathways for indoor cables that pass between
floors. It is normally a vertical shaft or space. Also a
fire code rating for indoor cable.
Riser cables: Riser cables are intended for use
in elevator (vertical) shafts between floors in a
building. Also a fire-code rating for indoor cable
connectorization.
Router: The central switching device in a packet-
switched computer network that directs and controls
the flow of data through the network.
RoHS: (The Restriction of Hazardous Substances
Directive) RoHS 2002/95/EC was adopted in February
2003 by the European Union. The RoHS took effect on
July 1, 2006, but is not a law; it is simply a directive
for participating countries, including the European
Union (exclusive of the United States and many other
countries). This directive restricts the use of six
hazardous materials in the manufacture of various
types of electronic and electrical equipment.
RoHS is often referred to as the "lead-free" directive.
Sag: The downward curvature of an aerial cable or
wire due to its weight.
Sheath, Cable: The protective outer covering over
the cable core.
Shield: A tape, serve or braid of metal, usually
copper, aluminum, or other conductive material
placed around or between electric circuits or cables
or their components, to prevent signal leakage or
interference.
Spare Pair: An additional pair in a cable, above
the guaranteed number, available in case a pair is
defective when it leaves the factory.
Splice Case: A metal or plastic housing used around
a cable splice to provide a water and gas tight
closure.
Structural Return Loss (SRL): Ratio of the reflected
power in a cable to the incident power expressed
in decibels. Effectively expresses the relationship
of impedance changes throughout a cable, as a
function of frequency relative to the characteristic
impedance of the cable. Important consideration for
transmission of Analog video. Used as a figure of
merit for consistency of impedance in a cable due
to changes in the cable’s construction or structure
down a long length.
T-1: Same as DS1.
Telcordia: Formerly Bell Core, a research company
once owned by the RBOCs.
TIA: The Telecommunications Industry Association.
TIA creates telecommunications standards.
UL: Underwriters Laboratories, Inc.
UTP (Unshielded Twisted Pair): Cable containing
one or more pairs of twisted copper without metallic
shielding.
Velocity of Propagation: The transmission speed of
electrical energy in a length of cable compared to
speed in free space. Usually expressed as
a percentage.
FIBER GLOSSARY OF TERMS
Absorption: The loss of light energy in an optical
fiber, resulting from conversion of optical power into
heat and caused primarily by impurities and defects
in the glass.
Aerial Cable: Fiber optic cable installed on aerial
supporting structures such as poles.
All-dielectric: Non-conducting; made entirely of
dielectric (insulating) materials, without any metal
conductors.
Aramid Yarn: Strength elements that provide
tensile strength, support and additional protection
of the fiber bundles. Kevlar
®
is a particular brand of
aramid yarn.
Armor: Additional protective covering beneath outer
jacket to provide physical protection against severe
outdoor environments. Usually made of plastic-
coated steel, it may be corrugated for flexibility.
Attenuation: A general term indicating the decrease
in power of a signal in transmission as it passes from
one point to another. In optical fibers, the power
loss results from absorption and scattering and is
normally measured in decibels (dB) per kilometer at a
specific wavelength.
Bandwidth: Measure of the information-carrying
capacity of an optical fiber. (This term is often used
to specify the normalized bandwidth of a multimode
fiber).
Bend Radius: The radius which a fiber or cable can
be bent before risking increased attenuation or fiber
breaks.
Blown Fiber: A method for installing fiber cable in
which the cable is blown through the duct.
Bonding: Electrically connecting the metallic
components of cable sheaths together.
Break Out Cable: Multi fiber cables where each
fiber is further protected by an additional jacket and
strength elements.
Breaking Strength: The amount of force needed to
break a fiber.
Broadband: Denotes transmission facilities
capable of handling a wide range of frequencies
simultaneously, thus permitting multiple channels in
data systems, rather than direct modulation.
Buffering: (1) An additional protective material
extruded directly over the fiber coating to protect it
from the environment and handling (tight-buffered);
(2) extruding a tube around the coated fiber to allow
isolation of the fiber from stresses in the cable
(buffer tubes).
Buffer Tubes: A hard plastic cylindrical tube, with a
diameter several times larger than the fiber, covering
optical fiber(s) used for protection and isolation.
Cable: An assembly of one or more optical fibers
formed into a core and covered with a protective
sheath providing mechanical and environmental
protection.
Cable Bend Radius: The effective radius resulting
when a cable is bent. Often specified as a minimum
bend radius that can be applied without causing
damage to the cable’s components.
Central Member: The center component in some
cable designs. It serves as a strength and anti-
buckling element The central member material is
typically either steel or glass-reinforced plastic.
Cladding: The material surrounding the core of an
optical fiber. The cladding must have a lower index of
refraction to keep the light in the core.