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Fiber Optic Center Glossary

View: Glossary, Acronyms, Military Specifications for Connectors

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There are currently 205 names in this directory beginning with the letter M.
mA. Milliampere
One-thousandth of an ampere (10-3).

Machine polishers
Automated polishers that are capable of polishing from two to 32 connectors at one time. These polishers can provide uniform low reflection polishes (e.g., PC, SPC, UPC, APC).

In an optical fiber, all macroscopic deviations of the axis from a straight line; distinguished from microbending.

A cyclic macromolecule or a macromolecular cyclic portion of a molecule. (IUPAC)

A large-sized molecule; another name for polymer. a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of a number of constitutional units. (IUPAC)

A monomer which is a polymer of an oligomer. (IUPAC)

Macromonomeric unit / macromer
The largest constitutional unit contributed by a single macromonomer molecule to the structure of a macromolecule. (IUPAC)

Magnet Wire
Insulated wire intended for use in windings on motor, transformer, and other coils for electromagnetic devices.

Magnetic Field
The region within which a body or current experiences magnetic forces.

Magnetic Flux
The rate of flow of magnetic energy across or through a surface (real or imaginary).

Magnetic Noise
Caused by current frequency. An AC powerline creates a magnetic field around that cable. This magnetic field causes the magnetic noise in neighboring control or instrumentation circuits.

Main chain / backbone
That chain to which all other chains (long or short or both) may be regarded as being pendant; where two or more chains could equally well be considered to be the main chain, that one is selected which leads to the simplest geometrical representation of the molecule. (IUPAC)

Main cross-connect (MC)
A cross connect for first and second level cabling, e.g., from equipment facility connecting to all other locations (ICs and HCs). Usually would consist of a distribution or patch panel.

Main distribution frame (MDF)
A wiring arrangement that connects the telephone lines coming from outside on one side and the internal lines on the other. A main distribution frame may also carry protective devices as well as function as a central testing point. The MDF has been changed to "MC" (main cross-connect) in ANSI/EIA/TIA-568-B.2. The MC is the point at which outside service lines interface to inside service and then to IC’s or to TC’s.

A large computer system.

Mainframe OTDR
An OTDR with a larger chassis than a mini OTDR. Mainframe OTDRs have CRT displays, internal printers and are larger and heavier than most OTDRs. They were the most common type up till the early 1990s. Mainframes could also be provided with different laser and fiber modules as needed.

Major Trading Area (MTA)
A personal-communications-service area designated by Rand McNally and adopted by the Federal Communications Commission to determine the 51 MTAs in the US.

Manchester Encoding
An encoding method which involves a digital state change (0 to 1 or vice versa) for every bit representation occurring in the middle of the transmitted bit. Useful in local area networks because it is self-clocking. The receiver can develop the data clock from the transmitted data stream. Used in Token Ring and Ethernet systems. Standard Ethernet uses Manchester encoding which results in 10 Mbps throughput at 10 MHz frequency (one-for-one).

A mechanical device of a specific diameter that strips out higher order modes from multimode fibers.

Manufactured Unit
A quantity of finished adhesive or finished adhesive component, processed at one time. (Compare batch.) Discussion—The manufactured unit may be a batch or a part thereof.

Multiple Application Platform, Linux powered chassis

MAP 1-step Reference Method
Unidirectional, Single MTJ. DUT end referenced to mORL detector. Used when two ILs are required, one for each end.

MAP 2-step Reference Method
Bi-Directional, Dual MTJ each referenced to mORL but not to each other. Used when MTJ cannot be mated to each other. Gives total IL.

MAP 3-step Reference Method
Uni or Bi-directional, dual MTJ, each referenced to mORL and to each other. Gives total IL.

The act of associating logical representations with their physical counterparts.

The amount of additional loss that can be tolerated in a link.

Marine Eye
A style of hardware with a drilled eye and a drilled shank into which wire rope is inserted for swaging

Marker Tape
A tape laid parallel to the conductors under the jacket in a cable, imprinted with manufacturer's name and/or specification to which the cable is made.

Marker Thread
A colored thread laid parallel and adjacent to the strands of an insulated conductor which identifies the cable manufacturer. It may also denote a temperature rating or the specification to which the cable is made.

A printed identification number or symbol applied to the surface of tubing or cable jackets.

Marline Spike
Tapered steel pin used in splicing wire rope

Mulitcast Address Resolution Server

A peelable, water soluble, or solvent soluble compound that is used to prevent solder from filling in areas that need to be solder free. 

Master Antenna Television (MATV)
A combination of components providing multiple television receiver operations from one antenna or group of antennas normally on a single building.

Meltable coating used on the inside of some shrink products which, when heated, flows to encapsulate the interstitial air voids.

Mastic adhesive
A gap-filling adhesive applied as a paste or putty-like material.

Matched-clad optical fiber
Optical fiber with a cladding of consistent refractive index up to the core boundary, resulting in the desired single-mode step-index profile. Used where fibers of different periods are spliced together as they produce lower attenuation readings and are less susceptible to bending losses.

The joining of two connectors. (MIL-STD)

a substance useful for structural purposes.

Material dispersion
Dispersion caused by differential delay of various wavelengths of light in a waveguide material.

Material safety data sheet (MSDS)
Technical bulletin required by OSHA detailing information about the physical or health hazards of a chemical or mixture.

Material Scattering Loss
Loss due to fluctuations in the refractive index and to inhomogeneities in material composition and temperature.

Mating connector
A connector on the test fixturing that connects, or mates, to a connector on the device-under-test.

Mating Face
1) Shared boundary defined by common physical interconnection characteristics (often including a connector), signal characteristics and meanings of interchanged signals.  2) A device or equipment making inter-operation of two systems possible; for example, a hardware component or common storage register.  3) The two surfaces on the contact side of a mating connector or plug-in component (e.g. relay) and receptacle, which face each other when mated. (MIL-STD)Also called Interface.

Mating Face Seal
A seal which prevents the passage of moisture or gases into or out of the connecting interface of two connectors in mated condition.

The part of an adhesive which surrounds or engulfs embedded filler or reinforcing particles and filaments.

Maturing temperature
The temperature, as a function of time and bonding condition, that produces desired characteristics in bonded components. Discussion—The term is specific for ceramic adhesives.

A type of flexible fabric inner duct used to increase capacity of ducts.

Mean time between failure (MTBF)
Developed by the military to estimate maintenance or replacement times for various pieces of high-end equipment, MTBF is based upon statistical evidence derived from in use testing under extreme conditions (simulated or actual environment). Testing is performed by the manufacturer of the equipment or an independent test facility.

Mechanical adhesion
See mechanical adhesion under adhesion.

Mechanical splice
A fiber splice accomplished by fixtures or materials, rather than by thermal fusion. Index matching material may be applied between the two fiber ends. A semi-permanent connection between two fibers, made with an alignment device and refractive index matching fluid or adhesive.

The step-by-step changes by which a chemical reaction occurs

MEDIA (Telecommunications)
Wire, cable or conductors used for telecommunications.

Media outlet
A small patch panel located at work areas allowing quick termination of voice, video, and data connectors.

Media, Telecommunications
Wire, cable, or conductors used for telecommunications.

Material used for the transmission of signals.

Medium Voltage
2001 Volts to 35KV.

Medium-density polyethylene (MDPE)
A flexible, environmentally-stable thermoplastic used in outside cable jacketing.

Mega (M)
One million, or 1,000,000

Megabit (Mb)
One million bits.

Megahertz (MHz)
One million cycles per second.

A unit for measuring radiation dosage. 1 megarad = one million rads = 106 rad or 106 cJ/kg.

An instrument used to measure insulation resistance (Readings are in megohmes).

Melt Extrude
To heat a material above its crystalline melt point and extrude it through an orifice.

Melting Point
The temperature at which crystallinity disappears when crystalline material is heated.

A group of insulated wires to be cabled with other stranded groups into multiple-membered cable.

Membrane Press
A hot press design which permits laminates or veneer to be glued to a surface that is not flat, by using a rubber membrane that is inflated with a hot fluid.

Membrane pressing
A process in which an adherend is brought in intimate contact with a substrate to form an assembly by application of overpressure to a flexible film.

Micro-Electromechanical Sytems

An organic compound containing –SH groups; a main curing agent for polysulfide adhesives and sealants.

Message switching
Enables a single communications channel to be used simultaneously for more than one node.

The linear supporting member, usually a high strength steel wire, used as the supporting element of a suspended aerial cable. The messenger may be an integral part of the cable, or on the exterior.

Messenger Strand
Galvanized strand or bronze strand used to support telephone and electric cables

Messenger wire
Galvanized wire ranging from 1/4” to 9/16” which is placed between poles and which standard cable types are lashed.

Metal foil
Thin, flexible sheets of metal (e.g. aluminum and lead) used as tape backings because of inherent properties such as weather-resistance, reflectivity, etc.

Metal To Metal Bottoming
In cylindrical connectors, the situation in which the shell surface of the receptacle bottoms (contacts) the inside rear portion of the mating plug.

Meter (m)
One meter equals 3.281 feet.

Method of Moments
Equations for numerically computing electromagnetic fields.

Metric Cable
Cable designed and manufactured to metric sizes and tolerances

Metropolitan area network (MAN)
An interconnected data transmission system connecting users and LANs in a localized geographical area such as a city.

Metropolitan Statistical Area (MSA)
An MSA denotes one of the 306 largest urban population markets as defined by Rand McNally and designated by the Federal Communications Commission as a guide to determine coverage areas for cellular networks. Two cellular operators are licensed in each MSA.

MFC Library
Microsoft Foundation Class Library

An electrical unit of conductivity, being the conductivity of a body with the resistance of one ohm.

MHV (Miniature High Voltage)
Coaxial connector with bayonet coupling mechanism. Working voltage 2.2 kV DC.

One million cycles per second = megahertz = 106 Hz.

Micro (µ)
One millionth

Micro Farad
One millionth of a farad. This is the common unit for designating capacitance in electronics and communications.

Curvatures of the fiber which involve axial displacements a few micrometers and spatial wavelengths of a few millimeters. Microbends cause loss of light and consequently increase the attenuation of the fiber. An effect where small stresses or flaws create attenuation. Mostly an extrinsic effect caused by tie wraps and point deformations onto the fiber that allow light to escape. Intrinsic sources are flaws or defects in the core/cladding boundary created during the manufacturing process.

Microbending Loss
Loss due to small geometrical irregularities along the core-clad interface of the fiber.

A small cell site in a personal-communications-services network. Personal-communications-services networks use many microcells.

Small HDPE ducts up to 16 mm in diameter that can be installed in empty or partially filled ducts to provide space for microduct fiber optic cables.

Microduct cable
Microduct cables are designed for high-density fiber counts in a small optical cable, normally between 5-16 mm. Designed for blowing into microducts.

Microfarad (MF)
One-millionth of a farad (uf, ufd, mf and mfd are common abbreviations).

Micrometer (µm)
One millionth of a meter or a micron. Conventional unit of measurement for optical fibers.

One-millionth of a microfarad (uuf, uufd, mmf, mmfd mm F are common abbreviations).

Micron (um)
Millionth of a meter = 10-6 meter.

Noise in a system caused by mechanical vibration of components within the system.

Microscope, fiber optic inspection
A microscope used to inspect the end surface of a connector for flaws or contamination or a fiber for cleave quality.

A type of transmission line configuration which consists of a conductor over a parallel ground plane and separated by a dielectric.

A short (usually less than 30 cm.) electrical wave. RF signals between 890-MHz and 20-GHz. Point-to-point microwave transmission is commonly used as a substitute for copper or fiber cable.

Microwave Frequency
The frequency of a microwave, usually above 1 gigahertz.

Opening a cable in the middle of a span to access the fibers. Also known as an express entry.

Referring to an inlet or outlet with a shallow depth. Commonly mounted in areas where space is limited.

Mobile Information Device Profile

The movement of some metals, notably silver, from one location to another.

MII Format
A video recording format used by broadcasters.

1) Military specification for wire; 2) 0.001" (1/1000 inch) one 1000th of an inch; 3) A unit used in measuring diameter of wire or thickness of an insulation over a conductor.

DSCC specification for Radio Frequency cables, flexible and semi-rigid.

United States Defense Standard, often called a military standard, "MIL-STD", or "MIL-SPEC". A MIL-SPEC for quality standards for electronic parts is MIL-STD-202. 

Military Specification
A specification governing the manufacture of specialty wire ropes and aircraft cables required in various military and non-military applications. See Cable Specifications

Military tactical cable
Heavy-duty cable designed for rugged installations and operations.


Millimeter (mm)
One millimeter equals 0.03937 inches.

An abbreviation for minimum calculated effective modal bandwidth, minEMBc is used to calculate the bandwidth of multimode fiber at Gigabit data rates.

Mineral Insulated
Cable and thermocouple wire consisting of one or more conductors surrounded by magnesium oxide insulation and enclosed in a liquid- and gas-tight metallic sheathing.

Mini OTDRs emerged in the 1990s as a low-cost, lightweight version of the mainframe OTDR. Features include AC/DC power, LCD display, and various modules for specific fiber types and corresponding wavelengths. Usually without a printer, they can store traces on disk, memory card, or their internal hard disk.

Mini Zipcord
A separable two-fiber breakout style cable.

Miniature Wire
Insulated conductors of approximately 20-34 AWG.

MiniBNC connector
A keyed connector with a 2.5-mm ferrule and bayonet coupling mechanism. It was the predecessor to the ST connector.

Minimum Bending Radius
Ratio of the diameter of the pulley used in an application (D) to the diameter of the wire rope (d)

Minimum Dynamic Bending Radius
The minimum permissible radius for flexible applications of the cable.

Minimum Static Bending Radius
The minimum permissible radium for fixed installation of the cable. This radium is used I climatic tests.

Mining Cable
A flame retardant cable especially constructed to withstand long time immersion or exposure to moisture for underground use in the environment of a mine or tunnel.

A termination having a different impedance from that for which a circuit or cable is designed.

Mismatch (Connector Impedance or Line Impedance)
1) The condition in which the impedance of a source does not match or equal the impedance of the connected load. This reduces power transfer by causing reflection.  2) A termination having a different impedance than that for which a circuit or cable is designed.

An unintended connection which is the result of a misplaced contact within a connector.

Mobile Telephone Switching Office (MTSO)
The central computer that connects a cellular-phone call to the public telephone network. The MTSO controls the entire system’s operations, including monitoring calls, billing, and handoffs.

Modal Dispersion
Pulse spreading due to multiple light rays traveling different distances and speeds through an optical fiber.

A light path. One of the components of a general configuration of a propagating wave front.

Mode (Fiber Optic)
One of the components of a general configuration of a propagating wave front. Mode is characterized by a particular geometrical pattern and propagation constant.

Mode conditioning patchcord (MCPC)
Designed for GbE and Fibre Channel links using legacy multimode fibers and VCSEL light sources operating at 850 nm. Normally it is a pair of duplex jumpers that are installed between the transmission equipment at each end of the fiber link. The transmit side has a short single-mode section “offset” fusion spliced to MMF so the light is coupled outside of the center core defect of the MMF. The receiver portion is entirely multimode.

Mode coupling
In an optical fiber, the exchange of power among modes. The exchange of power may reach statistical equilibrium length.

Mode field diameter
A measure of the core size in singlemode fiber.

Mode Field Diameter (MFD)
The diameter of optical energy in a singlemode fiber. Because the MFD is greater than the core diameter, MFD replaces core diameter as a practical parameter.

Mode filter
A device that removes optical power in higher order modes in fiber.

Mode power distribution (MPD)
The relative mode power in each mode groups of a multimode fiber.

Mode scrambler
A device that mixes optical power in fiber to achieve equal power distribution in all modes. Mode stripper: A device that removes light in the cladding of an optical fiber.

Device which places and receives data signals over a common carrier's communication facility.

Any chemically inert ingredient added to an adhesive formulation that changes its properties.

Modular Jack
This term is outmoded, see Outlet/Connector, Telecommunications.

Modular Plug
A series of connectors designed for ease of use and flexibility. They are characterized by locking plastic tabs on the bottom and typically appear in three configurations: RJ-11 (4-conductor), RJ-12 (6-conductor) and RJ-45 (8-conductor).

Modulated laser
A laser module that allows users to control output power by varying a control voltage, which turns the laser on and off.

In fiber optics, the manner in which information is coded into light for transmission through a fiber.

A waveguide device used externally to the laser to electrooptically change the refractive index of the waveguide in response to an applied electric field. The phase changes induced can result in amplitude modulation of light at the output port.

Modulus of Elasticity
The ratio of stress to strain in an elastic material.

Modulus, secant
Slope of the line connecting the origin and a given point of the stress-strain curve.

Modulus, tangent
Slope of the line touching (tangent to) the stress-strain curve at a given point on the curve.

Moisture Absorption
The amount of moisture , in percentage, that a material will absorb under specified conditions.

Moisture Content
Percent moisture content is equal to the weight of water divided by the weight of bone-dry wood x 100.

Moisture Meter
A small electronic device designed to determine the moisture content of wood stock.

Moisture Resistance
The ability of a material to resist absorbing moisture from the air or when immersed in water.

Mold, Potting, Electrical, Connector
An item, solid or split, designed to be used as a hollow form into which potting compound is injected and allowed to cure or set to seal the back of an electrical connector. The potting may eliminate the need for a backshell on the connector. The form may or may not be removable after potting.

Molded Plug
A connector molded on either end of a cord or cable.

Mono Filament
A single-strand filament as opposed to a braided or twisted filament.

Consisting of a single wavelength. In practice, radiation is never perfectly monochromatic but, at best, displays a narrow band of wavelengths.

Monochrome Signal
A television signal that does not contain any color information, a "black and white" signal.

The basic chemical unit used in building a polymer.

Monomeric unit / mer
The largest constitutional unit contributed by a single monomer molecule to the structure of a macromolecule or oligomer molecule. (IUPAC)

See single-mode.

Mooring Lines
Galvanized wire rope, usually 6x12, 6x24 or spring lay construction, for holding ships to dock

mORL Detector
2 mm detector for measuring Insertion loss.

mORL Module
The main “Engine” in any PCT setup, contains sources and detector

A printed circuit board used for interconnecting arrays of plug-in electronic modules or sub-assemblies.

Motor Lead Wire
Wire which connects to the usually fragile and easily damaged magnet wire found in coils, transformers, and stator or field windings. General requirements are abrasion resistance, toughness, flexibility, dielectric strength, thermal resistance and low pe

Moving Pictures Experts Group (MPEG)
Various standards, established by the, that define the amount of compression, and thereby the quality, of the resultant video information file.

Master Test Jumper, launch and receive test cables, high quality Jumpers used to connect between the MAP/PCT instrument and the DUT.

Multi-channel (4 to 72) connector from USConec (MPO is generic version).

MT-RJ connector. MT-RJ connector. A fiber-optic cable connector that is very popular for small form factor devices due to its small size. Housing two fibers and mating together with locating pins on the plug, the MT-RJ comes from the MT connector, which can contain up to 12 fibers.

MU Connector is a small form factor SC that looks like a miniature SC with a 1.25 mm ferrule. It is a popular connector type in Japan.

An adhesive prepared from a gum and water. Also in a more general sense, a liquid adhesive which has a low order of bonding strength.

External structural member in a curtain wall building, usually vertical. May be placed between two opaque panels, between two window frames, or between a panel and a window frame.

1000 volts 1000 volts

Multi-Conductor Cable
A cable consisting of two or more conductors, either cabled or laid in a flat parallel construction, with or without a common overall covering.

Multi-strand chain
A chain that comprises units always joined to each other through more than four atoms, more than two on each constitutional unit. (IUPAC)

A single packet of information sent to a specific subset of network addresses.

More than one conductor within a single cable complex.

Multifiber cable
An optical cable having more than one fiber.

Multifiber push-on connector (MPO)
A high-density connector that can terminate up to 24 singlemode or 72 multimode fibers in a single termination.

Multilongitudinal mode (MLM) laser
A laser, usually Fabry-Perot, that has a measured spectral width specified by the maximum root mean square of the spectral distribution (side modes), limited to no more than 20 dB down from the peak mode.

A means of conveying information with components in different media such as voice, music, text, graphics, image and video.

Multimedia Cable
A single communication cable used for the transmission of audio, data and video signals.

An instrument used to measure resistance, current and voltage. 

Many light rays (modes) propagating through the fiber core.

Multimode Fiber
An optical waveguide in which light travels in several modes. Typical core and cladding sizes are 62.5 and 125 µm, respectively.

Multimode Optical Fiber
An optical fiber that will allow many bound modes to propagate. The fiber may be either a graded-index or step-index fiber. See also: Optical Fiber Cable.

Multimode Propaganda
A method of introducing a light pulse with multiple light rays (modes) into an optical fiber. Multimode is typically used for short-haul applications of less than 2 KM using relatively inexpensive light sources usually operating at a 850 or 1300 nanometer wavelength. Gigabit Ethernet uses an 850 VCSEL laser while most other applications use Light Emitting Diode (LED) light sources.

A type of optical fiber that supports more than one propagation mode.

Multiple Conductor Cable
A combination of two or more conductors cabled together and insulated from one another and from sheath or armor where used.

Multiple Conductor Concentric Cable
An insulated central conductor with one or more tubular stranded conductors laid over it concentrically and insulated from one another.

Multiple system operator (MSO)
A cable television provider.

Multiple-Conductor Cable
A combination of two or more conductors cabled together and insulated from one another and from sheath or armor where used.

Multiple-layer adhesive
Film adhesive, usually supported, with a different adhesive composition on each side.

Combining two or more signals into a single bit stream that can be individually recovered.

Multiplexer (Mux)
A device which combines two or more separate signals for transmission through a single fiber. Optical multiplexer combines signals at different wavelengths. Electronic multiplexer combines TDM or FDM signals electronically before they are converted into optical form.

Simultaneous transmission of two or more messages over the same cable pair.

The ability of a system to run two or more processors simultaneously.

Multiprotocol label switching (MPLS)
An overall data-carrying protocol that encompasses circuit based and packet-switching services such as ATM, SONET, and Ethernet, as well as network digital formats such as VoIP and IPTV.

Multitenant data center (MTDC)
A facility that provides Internet infrastructure services, such as electrical power, fire suppression, security, cooling, and network access, usually over optical fiber. Some firms lease datacenter space to other providers or individual enterprises. Colocation data centers sell space on the basis of racks, cabinets, or cages.

Multiuser telecommunications outlet assembly (MUTOA)
Used in work areas of premises networks to allow multiple terminations.

Mutual Capacitance (Cm)
1) Capacitance between two conductors when all other conductors are connected together to shield and ground.  2) Capacitance between two conductors when all other conductors including ground are connected together and then regarded as an ignored ground.

Mutual Inductance
The ratio of voltage induced in one conductor to the time rate of current change in the separate conductor causing this induction.

A short form slang of multiplex. Also MUXED, MUXING.

mV (Millivolt)
One thousandth of a volt.

mW (Milliwatt)
One thousandth of a watt.

DuPont trademark for polyethylene terephtalate (polyester) film.
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