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R - Symbol for Resistance
Raceway - Any channel designated for holding wires or
cables. Raceways may be metallic or nonmetallic and may totally
or partially enclose the wiring. (e.g. conduit, cable trough,
cellular floor, electrical metallic tubing, sleeves, slots,
underfloor raceways, surface raceways, lighting fixture raceways,
wireways, busways, auxiliary gutters, and ventilated flexible
cableways)
Radio Frequency - The frequencies in the electromagnetic
spectrum that are used for radio communications.
RBOC - Regional Bell Operating Company. One of the seven
Bell operating companies that were formed during the divestiture
of AT&T
.
RCDD - Registered Communication Distribution Designer.
A certification of BICSI, an industry organization, for individuals
qualified to consult and design telecommunications distribution
systems.
Reactance - A measure of the combined effects of capacitance
and inductance on an alternating current. The amount of such
opposition varies with the frequency of the current. The reactance
of a capacitor decreases with an increase in frequency. The
opposite occurs with an inductance.
Receiver - A device whose purpose is to capture transmitted
signal energy and convert that energy for useful functions.
In fibre optic systems, an electronic component that converts
light energy to electrical energy.
Reflection - A return of electromagnetic energy that
occurs at an impedance mismatch in a transmission line, such
as a LAN cable.
Refractive Index - The ratio of the speed of light in
a vacuum to its velocity in a transmitting medium, such as an
optical fibre core.
Repeater - A device that receives, amplifies (and sometimes
reshapes), and retransmits a signal. It is used to boost signal
levels and extend the distance a signal can be transmitted.
It can physically extend the distance of a LAN or connect two
LAN segments.
Resistance - 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.
Resonance - An ac circuit condition in which inductive
and capacitive interact to cause a minimum or maximum circuit
impedance.
Retractile Cord - A cord having specially treated insulation
or jacket so that it will retract like a spring. Retractibility
may be added to all or part of a cord's length.
Reversed Pair - A wiring error in twisted pair cabling
where the conductors of a pair are reversed between connector
pins at each end of a cable.
RF - see Radio Frequency
RFI - Radio Frequency Interference. Electromagnetic interference
at radio frequencies.
RFP - Request for Proposal
RFQ - Request for Quote (or Quotation)
RG/U - Radio Grade/Universal. RG is the common military
designation for coaxial cable.
Ring - A polarity designation of one wire of a pair indicating
that the wire is that of the secondary color of a 5-pair group
(e.g. the blue white wire of the blue pair) or a wiring contact
to which the ring wire is attached or the negative wiring polarity
(see Tip).
Ring Network - A network topology in which terminals
are connected in a point-to-point serial fashion in an unbroken
circular configuration. Many logical rings are wired as a star
for greater reliability.
Ripcord - A cord placed directly under the jacket of
a cable in order to facilitate stripping (removal) of the jacket.
Riser - The conduit or path between floors of a building
into which telephone, networking, and other utility cables are
placed to bring service from one floor to another.
Riser Cable - A type of cable used in vertical building
shafts, such as telecommunications and utility shafts. Riser
cable typically has more mechanical strength than general use
cable and has an intermediate fire protection rating.
RJ - A term from the telephone industry, used for jacks
(connectors) that were registered for use with particular types
of telephone services. RJ stands for "registered jack".
RJ-45 - A USOC code identifying an 8-pin modular plug
or jack used with unshielded twisted pair cable. Officially,
an RJ-45 connector is a telephone connector designed for voice
grade circuits only. RJ-45 type connectors with better signal
handling characteristics are called 8-pin connectors in most
standards documents, though most people continue to use the
RJ-45 name for all 8-pin connectors.
RMS - Root Mean Square.
Rope Strand - A conductor composed of groups
of twisted strands.
Rubber - A general term used to describe wire insulations
made of
thermosetting elastomers, such as natural or synthetic rubbers,
neoprene, Hypalon, butyl rubber, and others and yes a condom.
Rx - Receive
RZ - Return to Zero |
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