(We wish to thank Unicom for their contributions.)
Quad – A four conductor cable.
Rated Temperature – The maximum temperature at which an electric component can operate for extended periods without loss of its basic properties.
Rated Voltage – The maximum voltage at which an electric component can operate for extended periods without undue degradation or safety hazard.
Reflection Loss – The part of a signal which is lost due to reflection of power at a line discontinuity .
Return Loss* – Noise or interference caused by impedance discontinuities along the transmission line at various frequencies. Return loss is expressed in decibels.
RFI (Radio Frequency Interference)* – Noise created in the radio-frequency range.
RG/U – “RG” is the military designation for coaxial cable, and “U” stands for “general utility”.
Riser Cabling* – That portion of a building’s cabling system which extends from the main distribution frame to the wiring closets. For data, this is often fiber optic cable. For voice, it is fiber optic cable if the PBX is distributed, and twisted pair copper cable otherwise.
RJ-11/12* – A standard connector commonly used to terminate voice connections.
RJ-45* – A standard connector commonly used to terminate data connections.
Router* – A layer-three device responsible for making decisions regarding which of several paths network traffic will follow. To do this, it uses a routing protocol to gain information about the network, and algorithms to choose the best route based on several criteria (known as routing metrics). Routers interconnect subnets.
Rope Lay Conductor – A conductor composed of a central core surrounded by one or more layers of helically laid groups of wires.
RS-232-C* – An Electrical Industries Association (EIA) Standard for the physical interface between Data Terminal Equipment (DTE) and Data Circuit Terminating Equipment (DCE).
SC* – A type of optical fiber connector. The SC utilizes the same 2.5mm ferrule as the ST, held in a housing that allows for “push-pull” insertion and removal of the connector of choice for data networks.
ScTP (Screened Twisted Pair)* – Copper cable that includes one or more sets of cable pairs which have been molded into an insulating material and covered by a braided shielding conductor. STP offers better noise protection than unshielded twisted pair (UTP) but is much more expensive and more difficult to use. Commonly associated with early token ring networks.
Sheath – The outer covering or jacket of a multiconductor cable.
Shield – In cables, a metallic layer placed around a conductor or group of conductors to prevent electrostatic or electromagnetic interference between the enclosed wires and external fields.
Shield Effectiveness – The relative ability of a shield to screen out undesirable radiation. Frequently confused with the term shield percentage, which it is not.
Signaling* – The process of sending information over media.
Single Mode fiber* – A form of fiber optic cabling in which light follows a single path as it traverses the cable. More expensive, and with a higher maximum rate and distance, than multi-mode fiber optic cable.
Skin Effect – The phenomenon in which the depth of penetration of electric currents into a conductor decreases as the frequency increases.
SNMP (Simple Network Management Protocol)* – An IAB protocol designed to manage networking devices. With SNMP, a management station can configure a supported device (SET), request that the device send statistical, status, and configuration information (GET), and receive unsolicited alarms from the device (TRAP).
SOHO* – Small Office / Home Office
Spark Test – A test designed to locate pinholes in the insulation of a wire or cable by application of a voltage for a very short period of time while the wire is being drawn through the electrode field.
Specific Gravity – The ratio of the density (mass per unit volume) of a material to that of water
Spiral Wrap – The helical wrap of a tape or thread over a core.
Spanning Tree* – A protocol specified in the IEEE 802.1 D standard which allows a network to have a topology that contains physical loops. Spanning Tree operates in bridges and switches. It opens certain paths to create a tree topology, thereby preventing packets from looping endlessly on the network.
SQE test* – A special 802.3 signal sent by MAU to the DTE to test the collision detection function. Commonly referred to as Heartbeat. DTEs request the SQE signal; repeaters do not.
ST* – A registered trademark of AT&T for their fiber optic connector. Originally, an acronym for “Straight Tip”.
Star* – A network topology in which each node is connected to a central point.
Station Cabling* – See “Horizontal Cabling”.
Store and Forward* – A method of switching in which a message is received as a whole, buffered, and then resent. All routers and virtually all current switches work in this manner. This method ensures that information being forwarded is free of errors.
STP (Shielded Twisted Pair)* – Copper cable that includes one or more sets of cable pairs which have been molded into an insulating material and covered by a braided shielding conductor. STP offers better noise protection than unshielded twisted pair (UTP) but is much more expensive and more difficult to use. Commonly associated with early token ring networks.
Strand – A single uninsulated wire
Stranded Conductor – A conductor composed of groups of wires twisted together.
Strip Force – The force required to remove a small section of insulating material from the conductor it covers. Usually measured in pounds.
Surface Resistivity – The resistance of a material between two opposite sides of a unit square of its surface. It is usually expressed in ohms.
Surge* – A rapid rise in current or voltage, usually followed by a fall back to a normal level. Also known as transient.
Sweep Test – Pertaining to cable, checking frequency response by generating an rf voltage whose frequency is varied back and forth through a giver frequency range at a rapid constant rate and observing the results of an oscilloscope.
Switch, Ethernet* – The Ethernet switch functions like a bridge to isolate traffic and separate collision domains. It’s objective is to increase throughput to each user by decreasing the number of stations that compete for the shared bandwidth. It also maintains a matrix of destination addresses and the physical ports associated with each address, so that it can switch frames/packets. An incoming frame/packet is only transmitted on the port associated with the frame’s destination address. The number of destination addresses is dependent on the vendor model of a switch, but can range from one to over one thousand.
Tape Wrap – A spirally applied tape over an insulated or uninsulated wire.
TC (Telecommunications Closet)* – Central location for termination and routing of on-premises wiring systems.
T-Connectors* – Connectors used to join thin Ethernet cable sections. The connectors also have a connector that is attached directly to a station.
Tear Strength – The force required to initiate or continue a tear in a material under specified conditions
Tensile Strength – The pull stress required to break a given specimen.
TIA (Telecommunications Industry Association)* – An organization that sets standards for cabling, pathways, spaces, grounding, bonding, administration, field testing and other aspects of the telecommunications industry.
Token ring* – A network architecture standardized in IEEE 802.5 in which the devices on a ring transmit data while they are in possession of a token which passes from node to node continuously. Token ring operates at 4 or 16 Mbps.
Topology* – Can be either physical or logical. Physical topology describes the physical connections of a network and the geometric arrangement of links and nodes that make up that network. Logical topology describes the possible logical connections between nodes, and indicates which pairs of nodes are able to communicate.
TP-PMD* – Twisted Pair Physical Media Dependent. ANSI X3T9.5 Committee’s proposed 100 Mbps over UTP Standard. Also referred to as CDDI (Copper Distributed Data Interface).
Transmission Cable – Two or more transmission lines. If the structure is flat, it is sometimes called Flat Transmission Cable to differentiate it from a round structure such as a jacketed group of coaxial cables.
Transceiver* – A device used in contention networks for sending and receiving data over the same network.
Transient* – A high-voltage burst of electric current, usually lasting less than 1 second, occurring randomly.
Tray – A cable tray system is a unit or assembly of units or sections, and associated fittings, made of metal or other noncombustible materials forming a rigid structural system used to support cables. Cable tray systems (previously termed continuous rigid cable supports) including ladders, troughs channels, solid bottom trays, and similar structures.
Triaxial Cable – A cable construction having three coincident axes, such as conductor, first shield and second shield all insulated from one another.
Trunk Cable* – Typically refers to a copper twisted pair backbone or vertical riser cable consisting of multiple groups of 25 pairs.
Twisted Pair* – Insulated copper wires twisted together with the twists or lays varied in length to reduce potential signal interference between the pairs. They are usually bundled together and wrapped in a cable sheath. New data grade Unshielded Twisted Pair (Category 5) is specified for 100 Mbps transmission.