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Fiber Optic Center Glossary

View: Glossary, Acronyms, Military Specifications for Connectors

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There are currently 202 names in this directory beginning with the letter F.
F-Block Carrier
A 10-MHz personal-communications-services carrier serving a basic trading area in the 1890-to-1895-MHz range paired with 1970-to-1975-MHz.

Fabry-Perot (FP) laser
A multilongitudinal mode laser diode with a semiconductor on each end to form a resonant chamber to create the lasing effect. Used in digital applications. Limited to 10 Gb/s speeds and used only for digital transmission.

Face Clearance
The distance between a glass plate and the edge of the stop.

Face Glazing
The method of glazing in which a rabbeted glazing recess, with no movable stop, is used and a triangular bead of compound is applied to the face of the lite and extended onto the recess (ASM C 717-07a).

Face Seal
A sealing of mated connectors over the whole area of the interface to provide sealing around each contact. (MIL-STD) Also called Interfacial Seal

Factor of Safety
Ratio of breaking strength of a wire rope to total rope stress

Failure, Adhesive
Rupture of an adhesive bond such that the separation appears to be at the adhesive substrate interface.

Failure, Cohesive
Condition of bond failure in which the adhesive falls apart.

Failure, Substrate
Condition of bond failure in which the substrate falls apart. The cohesive strength of the adhesive and the adhesive forces between the adhesive and substrate exceed the internal strength of the material being bonded.

Condition in which a tape pulls completely away from the surface to which it is applied and drops off.

False Ceiling
A ceiling that creates an area or space between the ceiling material and the structure above the material. Synonym: Drop Ceiling, Suspended Ceiling.

A device similar to a concentrator in that it provides multiple access to a single backbone tap.

Fanout kit
A kit designed for loose tube cable structures with multiple fibers per buffer tube. The fanout kit provides a 900-?m tubing over each 250-?m coated fiber strand, which allows for additional protection.

Far End Crosstalk (FEXT)
Refers to the undesired coupling of signals from the transmit pair onto the receive pair at the other (=far) end. FEXT isolation is also expressed in dB. For some applications this is an important parameter, for most applications however, the NEXT values are more important.

Far-End Crosstalk Loss (FEXT)
A measure of the unwanted signal coupling from a transmitter at the near-end into a neighboring pair measured at the far-end.

Farad (F)
The standard unit of capacitance whereby a charge of one coulomb produces a one volt potential difference. It indicates the charge per potential difference.

Faraday Shield
A conductive material used to contain or control an electric field. Placed between the primary and secondary windings of a transformer, it reduces coupling capacitance and common-mode noise. The shield provides electrostatic shielding while passing electromagnetic waves and requires no ground.

A unit of electric capacity.

Fast Ethernet
IEEE 802.3 standard operating at 100 Mb/s.

Fat Fiber
FOC specialty fiber market with connectors for more fiber sizes than any other company in the world (more than 40 hole sizes of SMA connectors, over 10 sizes of FCs, custom hole sizes (i.e., other than 125 um) in ST, SC, LC and other connectors).

Term commonly applied to progressive fracture of wires of a rope

Fatigue failure
Failure of a material as a result of rapid cyclic deformation

Fatigue Resistance
Resistance to metal crystallization which leads to conductors of wires breaking from flexing.

Break or stress in the continuity of the optical fiber’s normal performance.

Fault Find
A diagnostics feature on the IDEAL LAN Testers that allows you to determine where in a link a fault is located. (also see DOWNLINE IMPEDANCE)

Fault Finder
A simplified OTDR used to locate breaks in spans of fiber. See fiber break locator.

Fault Ground
A fault to ground.

Faying Surface
The surface of an adherend which makes contact with another adherend.

A connector type used primarily for Singlemode fiberoptic cable. It offers precise alignment of the cable with respect to the transmitter and detector. Using a threaded receptacle and a locator notch, once installed the position is maintained with absolute accuracy.

FDDI (Fiber Distributed Data Interface)
A standard for a 100 Mbs fiber optic area network.

The tapering of an adherend on one side to form a wedge section, as used in a scarf joint; in pressure sensitive tapes, a jagged, irregular paint line frequently characterized by small "feathers" of the top-coat projecting into the masked area.

Federal Communications Commission (FCC)
A board of five commissioners, appointed by the President, that regulates all electronic communications systems originating in the United States, including telephone systems. This government agency is responsible for the allocation of radio spectrum for communication services in the US

Feed-Through Insulators
Insulators that carry a metal conductor through the chassis while preventing the 'hot' lead from shorting to the ground chassis.

A connector or terminal block usually having double-ended terminals which permit simple distribution and bussing of electrical circuits. Also used to describe a bushing in a wall or bulkhead separating compartments at different pressure levels with terminations on both sides.

Energy that is extracted from a high-level point in a circuit and applied to a lower level. Positive feedback reduces the stability of a device and is used to increase the sensitivity or produce oscillation in a system. Negative feedback, also called inv

Feeder Cable
In telecommunication or CATV systems, the transmission cable from the head end (signal pickup) to the trunk amplifier. Also called a Trunk Cable.

(1) A conductor that connects patterns on opposite sides of a PCB. Also called Interfacial Connection; (2) A connector or terminal block, usually having double-ended terminals which permit simple distribution and bussing of electrical circuits.

FEP (Fluorinated Ethylene-Propylene)
Copolymer of PTFE and hexafluoropropylene. Electrical properties similar to PTFE, but temperature limited to 400°F (204°C).

Ferrimagnetic ceramic non-conductive compound material used to prevent high frequency electrical noise from entering or exiting the equipment.

Ferrite Material
Material made by calcining a combination of metal oxides sintered into tiles. Material only a few millimeters which absorbs low frequencies. These tiles may be used with dielectric materials or as a hybrid combination with dielectric pyramids.

Composed of and/or containing iron. A ferrous metal exhibits magnetic characteristics.

A component of a connector that holds fiber in place and aids in its alignment, usually cylindrical in shape with a hole through the center. A short tube used to make solderless connections to shielded or coaxial cable. An item molded into the plastic inserts of multiple contact and fiber optic  retaining springs can bear. Connections to provide strong, wear-resistant shoulders on which contact. A substance that is added to a material to improve its solidity, bulk , or other properties.

Any filament or fiber, made of dielectric materials, that guides light. Also, single discrete element used to transmit optical (light wave) information. See also Fiber Optics.

Fiber Amplifier
Most common are the erbium doped fiber amplifiers (EDFAs), semiconductor optical amplifiers (SOAs), and Raman amplifiers, which are used to increase signal gain without electrical conversion.

Fiber Bragg grating (FBG)
A piece of photo-refractive fiber that is exposed to high intensity UV interference patterns, causing it to reflect a specific wavelength while being transparent to all other wavelengths. Used as a filter in WDM systems.

Fiber Break Locator
A low-cost OTDR that is used to locate breaks in optical fiber cables.

Fiber Centers
Cords or rope made of vegetable fiber or synthetic fiber used in the center of a strand

Fiber Channel
A high speed point-to-point, ANSI Optical Communications Standard that supports data transfer rates up to 1,062.5 Mbs (1 Gps).

Fiber Cleaving
Controlled fracture of an optical fiber along a crystalline plane which results in a smooth surface.

Fiber Coating
A UV-cured material immediately surrounding the glass cladding that serves to protect the integrity of the fiber from surface damage and stresses. Normally 250 ?m for outside plant cables and 900 ?m for indoor cables.

Fiber Connector (FC)
A keyed connector with threaded coupling mechanism that has 2.5-mm ferrule. Mostly used in single-mode systems and test equipment.

Fiber Demarcation Box (FDB)
A fiber demarcation box provides a service provider with a customer disconnection point, either via a splice or connector interface. Slack cable storage and battery backup are stored here as well.

Fiber Dispersion
Pulse spreading in a fiber caused by differing transit times of various modes.

Fiber Distributed Data Interface (FDDI)
100 Mb/s ring architecture data network.. An American National Standards Institute (ANSI) standard for a fiber-based token ring physical and data link protocol that operates at a 100-Mbps data transfer rate. A duplex, counter-rotating, self-healing ring communication standard (ANSI X3T9) that provides a 100 Mb/s data format. Often used to interconnect low-speed protocols such as Token Ring and Ethernet.

Fiber distribution unit (FDU)
Enclosures that house and organize groups of fibers.

Fiber Identifier
A device that clamps onto a fiber and couples light from the fiber by bending, to identify the fiber and detect high speed traffic of an operating link or a 2 kHz tone injected by a test source.

Fiber in the loop (FITL)
An outside plant architecture deployed by telephone companies to provide broadband services to subscribers. In this architecture, SONET/SDH fiber runs from the telephone company central office to an optical networking unit. From the ONT, subscribers are served in a star topology with a drop of coax, twisted pair, or composite coax/twisted pair.

Fiber Optic Building Cable (LGBC)
A fiber optic cable in which individual optical fibers are formed into a cable for primary use in side building.

Fiber Optic Bundle
A number of fibers grouped together (rigid or flexible), usually carrying a common signal (or an image, or a conduit for transfer of light power).

Fiber Optic Cable
A communications cable that consists of one or more optical fibers, each capable of transmitting data via modulated light waves. Loose buffered types for outside plant applications can be armored or dielectric stranded or central tube designs. Applications include aerial figure-8, ducted, direct buried, all dielectric self-supporting (ADSS), and optical power ground wire (OPGW). Indoor designs are tight buffered breakout or distribution types with cable jackets designed to meet building codes for use in plenum, riser, and low smoke zero halogen environments.

Fiber Optic Center Catalog

Fiber Optic Connectors
Connectors designed to connect and disconnect either single or multiple optical fibers repeatedly. Fiber optic connectors are use to connect fiber cable to equipment and interconnect cables.

Fiber Optic Cross Connection
Fiber optic apparatus for terminating cable in couplings. Designed for high-density cross-connection fields, the apparatus can terminate up to 72 fibers on each shelf, with up to nine shelves in a bay frame. Single shelves can also be wall mounted. Cross connections are handled with fiber optic patch cords. See also Patch Cord.

Fiber Optic Cross-Connect (LGX) Distribution System
A component of fiber optic cross-connect hardware. This component accommodates 24-216 fiber terminations. Also referred to as an LGX or shelf or frame.

Fiber Optic Interconnect
An interconnection unit used for circuit administration and built from modular cabinets. It provides interconnection for individual optical fibers but, unlike the fiber optic cross-connect panel, it does not use patch cords or jumpers. The fiber optic interconnect provides some capability for routing and rerouting circuits, but is usually used where circuit rearrangements are infrequent.

Fiber Optic Splice
A fiber optic cable splice is used to join together 2 or 24 fiber optic cable ends, permanently.

Fiber Optic Test Procedure (FOTP)
Standardized methods for testing various fiber optic components, as specified in the TIA-455 standard.

Fiber Optic Test Protocols
A series of test procedures defined by the FO 6.2 committee of TIA. The procedures cover a wide number of situations, for example, verification by manufacturers of cable specifications, cable bend radius, connector manufacturing, fire rating, and field testing of fiber optic installations.

Fiber Optics
A lightwave or optical communications system in which electrical information is converted to light energy transmitted to another location through optical fibers, and is there converted back into electrical information. Branch of optical technology dealing with the transmission of radiant power through fibers made of transparent materials such as glass, fused silica, or plastic. Term used to describe links used for voice, video, data, medical, sensing, and illumination applications. All use optical fibers to transmit or receive optical signals or power. Light transmission through flexible transmissive fibers for communications or lighting.

Fiber Optics LAN Section
Known as FOLS, a group operating within the trade association operation of TIA. FOLS is dedicated to promoting the common interests of TIA members involved in fiberoptic telecommunications.

Fiber Proof Testing
A mechanical tensile test used to measure the axial strength of an optical fiber, normally 100 kpsi.

Fiber Saturation Point
The moisture content of wood at which all unbound moisture has been eliminated. This is typically about 30% Moisture Content.

Fiber Sensor
A sensing device in which the active sensing element is an optical element attached directly to an optical fiber. The measured quantity changes the optical properties of the fiber so that it can be detected and measured.

Fiber surface finish
The quality of the polishing at the end of the fiber (1 mm, 0.3 mm, etc.). Some terms that describe a poor surface finish are: mist, hackle, chipped, or cracked.

Fiber Tear
In an FRP adhesively bonded joint, failure occurring exclusively within the fiber reinforced plastic matrix, charisterized by the appearance of reinforcing fibers on both ruptured surfaces.

Fiber to the antenna (FTTA)
See Fiber to the cell.

Fiber to the building/business (FTTB)
A topological reference to a network that supports multiple subscribers in a single structure, i.e., a business or a building. Multiple dwelling unit (MDU) defines residential use and multiple tenant unit (MTU) defines business units.

Fiber to the cell (FTTCell)
Fiber to the cell tower. Used to provide greater bandwidth and to transition to IP requirements using Ethernet.

Fiber to the curb/customer (FTTC)
Distribution of communication services by providing fiber optic links to a central point in each neighborhood and continuing to the homes by either twisted pair or coax.

Fiber to the desk (FTTD)
Transmission system using fiber optics from transmitter todesktop.

Fiber to the home (FTTH)
Distribution of communication services by providing fiber optic links all the way to each house. Protocols include active Ethernet and PON systems as defined by the IEEE, ITU, and SCTE.

Fiber to the node (FTTN)
An access network in which fiber is used for part, but not all, of the link from the OLT to the end user. An optical-to-electrical conversion takes place at a node, which typically serves a neighborhood. The terminal network segment is usually twisted copper pair (FTTC) or coaxial cable (HFC). Most current CATV and telephony networks have FTTN architectures.

Fiber tracer
An instrument that couples visible light into the fiber to allow visual checking of continuity and tracing for correct connections.

Fiber Tubing
A loose, crush-resistant cylinder applied over individual fibers to provide mechanical protection.

Fiber-reinforced plastic (FRP)
A plastic that contains fibers in various forms such as cloth, mat, strands, or chopped to enhance properties.

The trademark for glass which is formed into thin fibers and twisted and plied into yarns. It is used as protective braiding for cables. Normally saturated with silicone-base varnish to seal against moisture.

Fiber Optic Center term on their strong technical area in the manufacturing and testing of fiber optic cable assemblies, also known as patch cords. FOC is the only company in the world that can supply every piece of equipment needed to strip the cable, dispense and cure the epoxy, polish the terminated connector and perform all three kinds of testing: optical, geometry and visual inspection.

Fibre Channel
A high-speed interconnection ANSI standard for connecting supercomputers with peripheral devices up to 10 km away at transmission rates over 1 Gb/s. Used for the broadcast industry, storage area networks, and data centers.

An area of influence around a magnet or electric charge.

Field Coil
A suitable insulated winding to be mounted on a field pole to magnetize.

Field Effect Transistor (FET)
One of the two main amplifier types. FETs have limited frequency but are less noisy than bipolar circuits.

Figure 8 cable
A type of cable with a built-in messenger designed for aerial installations.

Figure 8 polishing
When a connector is polished on a lapping film/plate combination in a Figure 8 pattern to minimize scratches by using a different area of the lapping film.

Fiber characterized by extreme length.

File Server
A device found on local area networks which sends requested files and programs to requesting nodes and stores files sent from nodes.

Fill, Gap
Ability of an adhesive to fill the space between substrates and hold the substrates in place.

Filled Cable
A telephone cable construction in which the cable core is filled with a material that will prevent moisture from entering or passing through the cable.

(1) A material used in the cable to fill large interstices between electrical components; (2) A substance, often inert, added to a compound to improve properties and/or decrease cost.

Filler Sheet
Sheet of deformable or resilient material which, when placed between the assembly to be bonded and the pressure applicator, or when distributed within a stack of assemblies, aids in providing uniform application of pressure over the area to be bonded.

Filler Wire
Small auxiliary wires in a strand for spacing and positioning other wires

Non-conducting components cabled with the uninsulated conductors or optical fibers to impart roundness, flexibility, tensile strength, or a combination of all three, to the cable.

That portion of an adhesive which fills the corner or angle formed where two adherends are joined.

A thin plastic sheet. Uniform, homogenous on-fibrous synthetic webs.

Film Adhesive
An adhesive in film form, with or without a carrier, usually set by means of heat and/or pressure. The main advantage is uniformity of glueline thickness.

A devise which blocks the flow of EMI current while passing the desired 50/60/400-Hz current. When used in communications circuits, it suppresses unwanted frequencies and noise, or separates channels.

Filter Contact
A contact which provides R.F.I. suppression without altering its normal function.

Final Polish Film

Fine Stranded Wire
Stranded wire with component strands of 36 AWG or smaller.

Finger Joint
See finger joint under joint.

Finger Stock
A beryllium copper electrical gasket used to bond metal panel members on doors, sills or covers.

A material, device, or assembly of parts installed in a cable system in a fire-rated wall or floor to prevent passage of flame, smoke, or gasses through the rated barrier.

Operating instructions for a processor permanently stored in devices such as EPROM’s, and ROM’s which are hardware.

First Article
A sample part or assembly manufactured prior to the start of production for the purpose of assuring that the manufacturer is capable of manufacturing a product which will meet the requirements.

Small auxiliary wires in a strand for spacing and positioning other wires

Five Nines
Any system operating 99.999% of the time.

Fixed Contact
A contact which is permanently included in the insert material.

Fixture Time
Time needed for adhesive to reach sufficient strength to allow pieces to be handled and moved.

Fixture Wire
Fixture wires according to the National Electrical Code are designed for installation in lighting fixtures and in similar equipment where enclosed or protected and not subject to bending or twisting in use. They also are used for connecting lighting fixtu

The wires and connectors that connect the device-under-test to the tester.

Flame Resistance
Ability of the material to extinguish flame once the source of heat is removed.

Flame Retardance
Ability of a material to p revent the spread of combustion by a low rate of travel so the flame will not be conveyed.

The measure of the material's ability to support combustion.

Flammability Rating
Test methodologies of various organizations designed to simulate exposure to flame and burning, and the results of a material when tested under a specific methodology. Frequently used tests are UL94 (for testing materials as slabs or plaques), UL VW-1 or CSA FT1 (testing cable in a verticaly orientation), NEC CL2 (testing cables for general purpose communications which are installed within buildings), CSA FT6 (testing cable for horizontal flame and smoke)

Flammability Test
A test to determine the ability of a cable to resist ignition when placed near a source of heat or flame and to self-extinguish when removed from this source.

Describes any material that will ignite easily and burn rapidly.

Flange Connector
A projection extending from or around the periphery of a connector with provisions to permit mounting the connector to a panel or to another mating connector half.

A thin film of material formed at the sides of a forging, casting or molded part where some of the material is forced between the faces of the dies or mold halves

Flash Memory
Flash Erasable Programmable Read-only Memory is a form of computer semiconductor storage. It allows data in electronic format to be held without loss (unlike RAM) for an indefinite period (like ROM), and for the contents to be changed. It is a popular type of removable storage used for transporting data between recording devices and a PC.

Flash Plating
The application of extremely thin deposits of a plating material for environmental protection or as a base for a subsequent layer of plating.

Flash point
The lowest temperature at which the vapors being given off by a substance can be ignited.

A disruptive discharge around or over the surface of a solid or liquid insulator.

Flat Braid
A woven braid of tinned copper strands rolled flat at time of manufacture to a specified width.

Flat Cable
A cable in flat form, where the conductors lying parallel longitudinally but essentially with flat surfaces.

Flat Conductor
A wire having a rectangular cross section as opposed to round or square conductors.

Flat Conductor Cable
A cable with a plurality of flat conductors.

Flat Polish
A highly-reflection ferrule endface condition where fiber optic and ferrule tip are polished flat. Normally used with multimode fibers.

Flat Rope
Wire rope made of parallel alternating right lay and left lay ropes sewn together by relatively soft wires

Flat Under Carpet Cable
A cable containing one or more cores, each formed of a group of wires, the diameters of the wires being sufficiently small to afford flexibility.

Fleet Angle
Angle between position of a rope at the extreme end wrap on a drum, and a line drawn perpendicular to the axis of the drum through the center of the nearest fixed sheave

Flex Damage
Damage, usually occurring where a cord enters the housing, which is caused by the sharp bending of the cord. A strain relief or cable clamp restricts the concentration of flexing.

Flex Life
The number of cycles that a cable can withstand before failure when bent around a specific radius. The ability of a cable to bend many times before breaking.

Flex Life Test Types
Testing methodologies used to evaluate the durability and reliability of a cable or assemly under repeated bending. Three methods are frequently used: Weighted Bend, Bend, or Rolling Bend. The Weighted Bend test holds a section of the cable aligned within a fixed holder and with a weight attached to the calbe below the holder (applied load). At a specific distance from the holder, the free end is bent to a 90 degree angle in one direction and then reversed to a 90 degree angle in the opposite direction. This is one flex cycle. The Bend test is the same as the Weighted Bend test without a weight (no load) attached to the cable. The Rolling Bend test holds one end of the cable in a fixed holder, the cable is formed into a U shape, and the free end of the cable is moved back and forth keeping the sides of the U at a fixed distance apart during the cycling

The ability of a cable to bend in a short radius (also see Limpness).

The quality of a cable or cable component which allows for bending under the influence of outside force, as opposed to limpness which is bending due to the cable's own weight.

Flexible Cable
A cable containing one or more cores, each formed of a group of wires, the diameters of the wires being sufficiently small to afford flexibility.

Referring to a circuit which has no connection to ground.

Flood Wiring
The concept of wiring for future growth, by providing full coverage of information outlets.

Floor Distributor
The distributor used to connect between the horizontal cable and other cabling subsystems or equipment (see telecommunications closet).

Flory-Huggins theory
A thermodynamic theory of polymer solutions, first formulated independently by Flory and by Huggins, in which the thermodynamic quantities of the solution are derived from a simple concept of combinational entropy of mixing and a reduced Gibbs-energy parameter, the `X parameter'. The X parameter is a numerical parameter employed in the Flory-Huggins theory, which accounts in the main for the contribution of the non-combinational entropy of mixing and for the enthalpy of mixing. (IUPAC)

Movement of an adhesive during the bonding process before the adhesive is set.

Fluorinated Ethylene Propylene (FEP)
FEP is similar to polytetrafluoroethylene (PTPE) but has a melting point of about 50° C lower and slightly different physical properties.

Fluorocarbon Films
A film with very high and low temperature limits, and excellent electrical characteristics. Typically exhibit a very slippery on-sticking surface. Note: One example is DuPont’s Teflon®.

A polymer that contains atoms of fluorine. Typical fluoropolymers are TFE, FEP, PFA, ECTFE and PVF.

(1) The lines of force which make up an electrostatic field; (2) The rate of flow of energy across or through a surface; (3) A substance used to promote or facilitate fusion .

Foam Polyethylene
See Cellular Polyethylene.

Foam Skin Cable
A cable utilizing a foamed polyolefin inner layer covered by a solid polyolefin skin as the conductor insulation.

Foamed Adhesive
An adhesive whose apparent density has been decreased by the presence of numerous gas-filled cells throughout its mass.

Foamed Plastics
Resins in flexible or rigid sponge formed with the cells closed or interconnected. Foamed insulations provide low dielectric contestants and weight savings.

Polyethylene foam insulation with polyethylene outerskin.

FOC Corporate Citizen
Fiber Optic Center support of select non-profit organizations by annual donations and hours of volunteerism.

Fiber Optic Center's video library of training, content and product demonstrations

Foil screened twisted pair cable (FTP)
A cable that use's a metallic Foil to surround the conductors in a Twisted Pair cable.

A thin supporting film of continuous sheet such as plastic foil, metal foil, laminated foil etc. for static shielding, contacts and other electrical applications.

A sleeve used to compress a grommet which tightens the seal around the wire entering the connector.

1) The area of the earth’s surface covered by a satellite signal.  2) The area of a printed circuit board covered by an electronic component such as a connector, IC, etc.

Forward error correction (FEC)
A method to improve the performance of large-capacity optical transmission systems. System designs employing FEC can accept relatively large BER (better than 10–12) in the optical transmission line before encoding.

Four wave mixing (FWM)
A collective name for a group of nonlinear processes where up to three different incident waves interact in the medium, resulting in a fourth wave.

Four-Wire Circuit
A transmission circuit using a transmit pair and a receive pair, or four wires altogether.

A metallic structure for hanging switch hardware.

Frame Relay
A packet-based technology that provides LAN-to-WAN connectivity over telephone lines at up to 1.5 Mb/s.

FRD (Fire Retardant)
A rating used for cable with Teflon or equivalent jacket and insulation. Use this cable when local fire codes call for low flame and low smoke, or when cable is run through a forced-air plenum.

Free Connector
A connector for attachment to the free end of a wire or cable.

Free Radical
A chemical component that contains a free electron which covalently bonds with a free electron on another molecule.

An adjective referring to a chain macromolecule the segments of which produce such small frictional effects when moving in a medium such that the hydrodynamic field in the vicinity of a given segment is not affected by the presence of other segments. Thus, the solvent can flow virtually undisturbed through the domain occupied by a freely-draining macromolecule. degree of polymerization the number of monomeric units in a macromolecule or oligomer molecule. (IUPAC)

Freeze/thaw stability
The ability of a product to remain usable after it has been frozen and thawed.

The number of cycles, now expressed as hertz, by an alternating current in one second. The hertz is equivalent to the older unit cycles per second.

Frequency Division Multiplexing (FDM)
Two or more signals combined at different frequencies so they can be transmitted as one signal.

Frequency Modulation (FM)
A scheme for modulating a carrier frequency in which the amplitude remains constant but the carrier frequency is displaced in frequency proportionally to the amplitude of the modulating signal. An FM broadcast is practically immune to atmospheric and man-made interference.

Frequency Re-Use
Because of their low power, radio frequencies assigned to one channel in a cellular system are limited to a single cell. Carriers are free, however, to re-use the frequencies again in other cells in the system without causing interference

Frequency Response
The characteristic of a device denoting the range of frequencies over which it may be used effectively.

Frequency-Division Muliplexing (FDM)
Simultaneous transmission of two or more messages over the same cable medium. Also called Multiplexing.

Fresnel reflection
Reflection of a portion of the incident light at a planar interface between connectors, mechanical splices, or two homogeneous media having different refractive indices.

A condition whereby mated surfaces move slightly and continually expose fresh metal. The exposed metal oxidizes and builds up until electrical continuity of the system is broken.

Fretting Corrosion
A form of excellerated oxidation that appears at the interface of contacting materials undergoing slight cyclic relative motion. All non-noble metals (i.e. tin) are susceptible to some degree of fretting corrosion and will suffer contact resistance increases.

Frictional Coefficient
A tensor correlating the frictional force F, opposing the motion of a particle in a viscous fluid, and the velocity u of this particle to the fluid. (IUPAC)

Front Mounted
A connector mounted on the outside of a panel or box with its mounting flange outside the equipment. (MIL-STD) A front mounted connector can only be installed or removed from the outside of the equipment.

Front Release Contacts
Connector contacts are released form the front side of the connector and then removed from the rear (wire side) of the connector. The removal tool engages the front portion of the contact and pushes it out the rear where it is removed by hand.

Full Cycling Control
Controls placed on the crimping cycle of crimping tools forcing the tool to be closed to its fullest extent completing the crimping cycle before the tool can be opened. (MIL-STD)

Full Duplex
In contrast to half-duplex devices, full duplex ones allow permanent, simultaneous two-way transmission of information, without interaction or interference of receive and transmit signals.

Full Duplex Ethernet
Full Duplex Ethernet will allow nodes to transmit and receive data at the same time, bringing aggregate throughput to 20 Mb/s. The CSMA/CD protocol may have to be disabled for the full duplex mechanism to function.

Full Duplex Transmission
1) Data transmission over a circuit capable of transmitting in both directions at the same time.  2) Synonymous with full duplex transmission. Also called Duplex Transmission.

Full spectrum wavelength division multiplexing (FSWDM)
A technology platform that uses spectrally enriched optical pulses for signal transmission at speeds of 10 Gb/s and higher.

Full width half maximum (FWHM)
Used to measure the spectral width of light sources. Measure the spectral width at 3 dB (half power from peak) and at the full width of the source’s power peak.

Full/full duplex
The primary can transmit to one secondary while simultaneously receiving from another secondary. In a typical multidrop LAN, the primary operates in full/full duplex mode while the secondaries operate in a half duplex mode.

Functional Group
A group of atoms on a monomer that can react with a group of atoms on a second monomer (Example: -COOH)

Funnel Entry
Flared or widened entrance to a terminal or connector wire barrel.

A safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level.

Fuse Wire
Wire made from an alloy that melts at a relatively low temperature .

Fused Coating
A metallic coating which has been melted and solidified, forming a metallurgical bond to the base material.

Fused Conductors
Individual strands of heavy tinned copper wire stranded together and then bonded together by induction heating.

Fused Spiral Tape
A PTFE insulated hookup wire. The spiral wrapped conductor is passed through a sintering oven whereoverlaps are fused together.

Fusion splicer
An instrument that splices fiber by fusing or welding the fibers, typically by an electric arc. A mechanical device that optically joins optical fibers by discharging voltage between two electrodes. Variations include the single fiber and ribbon fixed V-groove types, the profile alignment splicer (PAS) and the local injection detection (LID), both of which are categorized as core alignment splicers.
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