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M - Mutual Inductance
mA - Milliampere (one thousandth of an ampere)
MAC - see Medium Access Control
Main Cross Connect - A cross connect for first level
backbone cables, entrance cables, and equipment cables. The
main cross connect is at the top level of the premises cabling
tree.
Manchester Coding - A method of LAN signal encoding in
which each bit time that represents a data bit has a transition
in the middle of the bit time. Used with 10 Mbps Ethernet (10Base2,
10Base5, 10Base-F, & 10Base-T), and Token-Ring LANs.
Material Dispersion - Dispersion that results from each
wavelength traveling at a different speed than other wavelengths
through an optical fiber. Also called "chromatic dispersion".
MAU - Media Attachment Unit. The transceiver in Ethernet
networks. Also a common name for the MSAU (Multi-station Access
Unit) in Token-Ring networks.
Mbaud - Megabaud. One million baud.
Mbps - Megabits per second.
MC - see Main Cross Connect
MDF - Main Distribution Frame
MDI - see Media Dependent Interface
Media - Wire, cable, or conductors used for transmission
of signals.
Media Filter - An impedance matching component used in
Token-Ring networks to transform the 100 ohm impedance of UTP
cabling to the 150 ohm impedance of media interface connections.
Medium Access Control (MAC) - A mechanism operating at
the data link layer of local area networks which manages access
to the communications channel (medium).
Medium Dependent Interface (MDI) - In Ethernet, the connector
used to make the mechanical and electrical interface between
a transceiver and a media segment. An 8-pin RJ-45 connector
is the MDI for the 10Base-T, 100Base-TX, 100Base-T2, 100Base-T4,
and 1000Base-T media systems.
Medium Independent Interface (MII) - Used with 100 Mbps
Ethernet systems to attach MAC level hardware to a variety of
physical media systems. Similar to the AUI interface used with
10 Mbps Ethernet systems. An MII provides a 40-pin connection
to outboard transceivers (also called PHY devices).
Mega - Prefix meaning one million.
Megahertz (MHz) - One million hertz.
MIC - Medium Interface Connector. Duplex fiber optic
connector used with Fiber Distributed Data Interface (FDDI)
networks.
Micro - Prefix meaning one millionth.
Microfarad - One millionth of a farad. Abbreviated �F
(less commonly �fd, mf, and mfd).
Micron - One millionth of a meter. Abbreviated �m.
Midsplit Broadband - A broadcast network configuration
in which the cable is divided into two channels, each using
a different range of frequencies. One channel is used to transmit
signals and the other is used to receive.
MII - see Medium Independent Interface.
Mil - Unit of length equal to one thousandth of an inch
(0.001 inch).
Milli - Prefix meaning one thousandth.
Mixing Segment - Ethernet term used in IEEE 802.3 standards
to describe a segment that may have more than two MDI connections.
MMF - set Multimode Fiber
Modal Dispersion - Dispersion that results from the different
transit lengths of different propagating modes in a multimode
optical fiber.
Mode - A single electromagnetic wave traveling in an
optical fiber.
Mode Field Diameter - The diameter of optical energy
in a single mode fiber. Because the mode-field diameter is larger
than the core diameter, it replaces core diameter as a practical
parameter.
Modem - A device that implements "modulator-demodulator"
functions to convert between digital data and analog signals.
Modular Jack - The equipment mounted half of a modular
interconnection. Typically a female connector. A modular jack
may be keyed or unkeyed and may have six or eight contact positions,
but not all the positions need to be equipped with jack contacts.
Modular Plug - The cable mounted half of a modular interconnection.
Typically a male connector. A modular plug may be keyed or unkeyed
and may have six or eight contact positions, but not all the
positions need to be equipped with contacts.
Modulation - Altering the characteristics of a carrier
wave to convey information. Modulation techniques include amplitude,
frequency, phase, plus many other forms of digital encoding.
MSAU - Multi-station Access Unit. Device used to interconnect
lobe cables from stations on a Token-Ring network.
MT-RJ - Proposal for a new duplex fiber optic connector
standard from AMP/Siecor.
Multimode Fiber - A fiber optic cable which supports
the propagation of multiple modes. Multimode fiber may have
a typical core diameter of 50 to 100 �m with a refractive index
that is graded or stepped. It allows the use of inexpensive
LED light sources and connector alignment and coupling is less
critical than single mode fiber. Distances of transmission and
transmission bandwidth are less than with single mode fiber
due to dispersion.
Mutual Capacitance - Capacitance between two conductors
when all other conductors are connected together.
MV - Millivolt (one thousandth of a volt)
MW - Milliwatt (one thousandth of a watt)
Mylar - DuPont trademark for polyethylene terephtalete
(polyester) film. |
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