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mA


Abbreviation for milliamp. One thousandth of an Amp or 10-3 Amps.

 


MAC


Abbreviation for multiplexed analog components. A video standard developed by the European community. An enhanced version, HD-MAC delivers 1250 lines at 50 frames per second, HDTV quality.

 


Macrobending


In a fiber, all macroscopic deviations of the fiber’s axis from a straight line, that will cause light to leak out of the fiber, causing signal attenuation.

Macrobending
 


MAN (Metropolitan Area Network)


A network covering an area larger than a local area network. A series of local area networks, usually two or more, that cover a metropolitan area.

MAN (Metropolitan Area Network)
 




MAP


Abbreviation for manufacturing automation protocol. Computer programs that run manufacturing automation systems.

 


Margin


Allowance for attenuation in addition to that explicitly accounted for in system design.

 


Material Dispersion


Dispersion resulting from the different velocities of each wavelength in a material.

Material Dispersion
 


MBaud


One million symbols of information per second. Equivalent to 1 mb/s for binary signals.

 


Mean Launched Power


The average power for a continuous valid symbol sequence coupled into a fiber.

 


Mechanical Splice


An optical fiber splice accomplished by fixtures or materials, rather than by thermal fusion. The capillary splice, illustrated, is one example of a mechanical splice.

Mechanical Splice
 


Medium Access Control (MAC)


1) A service feature or technique used to permit or deny use of the components of a communication system. 2) A technique used to define or restrict the rights of individuals or application programs to obtain data from, or place data onto, a storage device, or the definition derived from that technique.

 


Mezzanine Compression


Contribution level quality encoded high-definition television signals. Typically split into two levels: high level at 140 Mb/s and low level at 39 Mb/s. For high definition within the studio, 270 Mb/s is being considered.

 


MH


Abbreviation for medium-haul. A classification of video performance under RS-250C. Higher performance than long-haul and lower performance than short-haul.

 


MHz


Abbreviation for megahertz. One million Hertz (cycles per second).

 


Microbending


Mechanical stress on a fiber that introduces local discontinuities,  which results in light leaking from the core to the cladding by a process called mode coupling.

Microbending
 


Microbending


Mechanical stress on a fiber that introduces local discontinuities,  which results in light leaking from the core to the cladding by a process called mode coupling.

Microbending
 


Micrometer


One millionth of a meter or 10-6 meters. Abbreviated μm.

 


Microsecond


One millionth of a second or 10-6 seconds. Abbreviated μs.

 


Microwatt


One millionth of a Watt or 10-6 Watts. Abbreviated μW.

 


Microwave Dish


A parabolic shaped antenna used for high-frequency RF signals.

 


Microwave Transmission


Communication systems using very high-frequency RF to carry the signal information.

 


MIL-SPEC


Abbreviation for military specification. Performance specifications issued by the Department of Defense that must be met in order to pass a MIL-STD.

 


MIL-STD


Abbreviation for military standard. Standards issued by the Department of Defense.

 




Minimum Bend Radius


The smallest radius an optical fiber or fiber cable can bend before increased attenuation or breakage occurs.

 


Misalignment Loss


The loss of power resulting from angular misalignment, lateral displacement, and fiber end separation.

 


 


Modal Noise


Noise that occurs whenever the optical power propagates through mode-selective devices. It is usually only a factor with laser light sources.

 


Mode


A single electromagnetic wave traveling in a fiber.

 


Mode Coupling


The transfer of energy between modes. In a fiber, mode coupling occurs until equilibrium mode distribution (EMD) is reached.

 


Mode Evolution


The dynamic process a multilongitudinal mode laser undergoes whereby the changing distribution of power among the modes creates a continuously changing envelope of the laser’s spectrum.

 


Mode Field Diameter (MFD):


A measure of distribution of optical power intensity across the end face of a single-mode fiber.

 


Mode Filter


A device that removes higher-order modes to simulate equilibrium mode distribution. A mode filter is most easily constructed.

Mode Filter
 


Mode Scrambler


A device that mixes modes to uniform power distribution.

Mode Scrambler
 


Modem


Acronym for modulator/demodulator. 1) In general, a device that both modulates and demodulates signals. 2) In computer communications, a device used for converting digital signals into, and recovering them from, quasi-analog signals suitable for transmission over analog communications channels such as telephone lines.

 


Modulation


The process by which the characteristic of one wave (the carrier) modifies another wave (the signal). Examples include amplitude modulation (AM), frequency modulation (FM), and pulse-coded modulation (PCM).

 


Modulation Index


In an intensity-based system, the modulation index is a measure of how much the modulation signal affects the light output. It is defined as follows:

m = (highlevel - lowlevel) / (highlevel + lowlevel)

 


Modulator


A device that imposes a signal on a carrier.

 


Monitor


1) a CRT that receives its signal directly from a VCR, camera, or separate TV tuner for high-quality picture reproduction. 2) A device used for the real-time temporary display of computer output data. 3) Software or hardware that is used to scrutinize and to display, record, supervise, control, or verify the operations of a system.

Monitor
 


Monochrome


Black and white TV signal.

 


Moore’s Law


A prediction for the rate of development of modern electronics. It states that the density of information storable in silicon roughly doubles every year. Or, the performance of silicon will double every eighteen months, with proportional decreases in cost. For more than two decades this prediction has held true. Named after Gordon E. Moore, physicist, cofounder and chairman emeritus of Intel Corporation.

 


Most Significant Bit


In a binary code, the bit or bit position that is assigned to, or represents, the largest quantity or increment that the code can represent.

 


MPEG


Abbreviation for motion picture experts group. An international standard for compressing video that provides for high compression ratios. The standard has two recommendations: MPEG-1 compresses lower-resolution images for videoconferencing and lower-quality desktop video applications and transmits at around 1.5 Mb/s. MPEG-2 was devised primarily for delivering compressed television for home entertainment and is used at CCIR resolution when bit rates exceed 5.0 Mb/s as in hard disk-based applications.

 


ms


Abbreviation for milliseconds. One thousandth of a second or 10-3 seconds.

 


MSO


Abbreviation for multiple service operator. A telecommunications company that offers more than one service, e.g. telephone service, Internet access, satellite service, etc.

 


MTBF


Abbreviation for mean time between failure. Time after which 50% of the units of interest will have failed. Also called MTTF (mean time to failure).

 


Multi-quantum Well (MQW) Laser


A laser structure with a very thin (about 10 nm thick) layer of bulk semiconductor material sandwiched between the two barrier regions of a higher bandgap material. This restricts the motion of the electrons and holes and forces energies for motion to be quantized and only occur at discrete energies.

 


Multilongitudinal Mode (MLM) Laser


An injection laser diode which has a number of longitudinal modes.

Multilongitudinal Mode (MLM) Laser
 


Multimode (MM) Fiber


An optical fiber that has a core large enough to propagate more than one mode of light The typical diameter is 62.5 micrometers.

Multimode (MM) Fiber
 


Multimode Dispersion


Dispersion resulting from the different transit lengths of different propagating modes in a multimode optical fiber. Also called modal dispersion.

 


Multiple Reflection Noise (MRN)


The fiber optic receiver noise resulting from the interference of delayed signals from two or more reflection points in a fiber optic span. Also known as multipath interference.

 


Multiplexer


A device that combines two or more signals into one output.

Multiplexer
 


Multiplexing


The process by which two or more signals are transmitted over a single communications channel. Examples include time-division multiplexing (TDM) and wavelength-division multiplexing (WDM).

 


MUSE


Abbreviation for multiple sub-nyquist encoder. A high-definition standard developed in Europe that delivers 1125 lines at 60 frames per second.

 


mV


Abbreviation for millivolt. One thousandth of a Volt or 10-3 Volts.

 


mW


Abbreviation for milliwatt. One thousandth of a Watt or 10-3 Watts.

 


MZ


Abbreviation for Mach-Zehnder, a structure used in fiber Bragg gratings and interferometers. Named for the two men who developed the underlying principles of the structure.