| Term |
Definition |
| MAC |
Media Access Control - The MAC layer is concerned with the control of access to a medium shared between two or more entities. It is a control layer for Ethernet. |
| MAC Address |
The 48-bit address used in Ethernet to identify a station. Generally a unique number that is programmed into a device at time of manufacture. |
| Manchester Encoding |
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 Mb/s Ethernet (10Base2, 10Base5, 10Base-F, & 10Base-T), and Token-Ring LANs. |
| Mapping |
In networking the logical association of one set of attribute values within one network with a set of attribute values within another network. |
| MASER |
Microwave Amplification by Stimulated Emission of Radiation - A special purpose microwave amplifier. Used extensively in satellite ground stations to amplify the signal received from space. |
| Master Clock |
A clock which generates accurate timing signals for the control of other clocks and possibly other equipment. |
| Matrix Switch |
A devices which performs "cross connect" switching functions automatically, under program control or under operator control. |
| Maximum Hops |
A packet switched network parameter which is used to limit the number of nodes through which a packet may pass in transit between source and destination. The limit is imposed to prevent the use of long (and time/resource consuming) end to end routes. |
| Maximum Time Interval Error |
The maximum peak to peak delay between a given timing signal and an ideal timing signal, within a particular observation period. |
| Mbits |
Megabits. |
| Mbps |
Megabits Per Second. |
| MCLED |
Micro Cavity LED. |
| MCM |
MultiChip Module. |
| MDAC |
Multiplying Digital to Analog Converter. |
| MDS |
Multipoint Distribution System. |
| Media Independent Interface (MII) |
Used with 100 Mb/s Ethernet systems to attach MAC level hardware to a variety of physical media systems. Similar to the AUI interface used with 10 Mb/s Ethernet systems. An MII provides a 40-pin connection to outboard transceivers. |
| Medium |
Any physical substance which is used for the transmission of signals. |
| Medium Attachment Unit |
A device used to attach a processing node, at the physical level, to a network. An example is the transceiver used to attach devices to an Ethernet cable. |
| MEGACO |
A protocol for IP Phone Media Gateways. |
| Megahertz |
One million hertz or one million cycles per second. |
| MESECAM |
A technique of recording SECAM video. Instead of dividing the FM color subcarrier by four and then multiplying back up on playback, MESECAM uses the same heterodyne conversion as PAL. |
| MESFET |
Metal Semiconductor Field Effect Transistor. |
| Metropolitan Area Network (MAN) |
A network where nodes within the same city or metropolitan area are connected together. |
| MFD |
Mode Field Diameter - The measure of the width of a guided optical power's intensity in a single mode laser. |
| MFM |
Modified Frequency Modulation. |
| MICRON |
A unit of measure equivalent to one-millionth of a meter; synonymous with micrometer. |
| Microwave |
Radio transmission in the high giga (billions) hertz range. Heavily used for data transmission over short (20-40 miles) distances. |
| Microwave Pulse Generator |
A device which generates pulses at microwave frequencies. |
| MIDI |
Musical Instrument Data Interface. |
| Midsplit Broadband |
A broadcast network configuration in which a broadband 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. For Ethernet, midsplit broadband is a configuration that can be used only with the 10Broad36 media system. |
| MIPS |
Million Instructions per Second. |
| M-JPEG |
Motion JPEG. |
| MMF |
Multi mode fiber. |
| MMU |
Memory Management Unit. |
| Modulation |
The process whereby a transmission signal is modified to carry any type of information. |
| Modulation Rate |
The reciprocal of the time interval between the shortest significant events (encodation bits for example) occurring in a modulated signal. If the measure is expressed in seconds the rate is given in BAUD. |
| Modulator |
A modulator is basically a circuit that combines two different signals in such a way that they can be pulled apart later. |
| Monotonic |
This is a term that is used to describe ADCs and DACs. An ADC or DAC is said to be monotonic if for every increase in input signal, the output increases. |
| MOS |
Metal Oxide Semiconductor. |
| MPEG |
Motion Picture Experts Group. |
| MPEG 1 |
An international standard for the digital compression of VHS-quality, full-motion video. |
| MPEG 2 |
A system, adopted by the Motion Picture Experts Group which was developed for compressing digitized video to save bandwidth. |
| MPEG 3 |
An international standard for the digital compression of broadcast-quality, audio. |
| MPEG 4 |
MPEG 4 uses an object-based approach, where scenes are modeled as compositions of objects, both natural and synthetic, with which the user may interact. Visual objects in a scene are described mathematically and given a position in a two- or three-dimensional space. Similarly, audio objects are placed in a sound space. Thus, the video or audio object need only be defined once; the viewer can change his viewing position, and the calculations to update the audio and video are done locally. Classical "rectangular" video, as from a camera, is one of the visual objects defined in the standard. In addition, there is the ability to map images onto computer-generated shapes, and a text-to-speech interface. |
| MPEG 7 |
MPEG 7 standardizes the description of multimedia material (referred to as metadata), such as still pictures, audio, and video, regardless if locally stored, in a remote database, or broadcast. Examples are finding a scene in a movie, finding a song in a database, or selecting a broadcast channel. The searcher for an image can use a sketch or a general description. Music can be found using a "query by humming" format. |
| MPMLQ |
Multipulse Maximum Likelihood Quantization - A speech compression technology which is the ITU compression standard G.723.1. It is very effective at low bit rates, maintaining a minimal level of distortion. |
| MPOA |
Multi-Protocol Over ATM - IETF defined specifications and procedures that enable Network Layer protocols to operate directly on top of ATM and provide end-to-end internetworking between hosts in an ATM and non-ATM environment. |
| MPSK |
Minimum Phase Shift Keying. |
| MQFP |
Metal Quad Flat Pack. |
| MR |
Magnetic Resonance. |
| MSD |
Most Significant Digit. |
| MSpS |
Mega Symbols per Second. |
| MTBF |
Mean Time Between Failures. |
| MTBM |
Mean Time Between Maintenance. |
| MTF |
Modulation Transfer Function. |
| MTS |
Multichannel Television Sound. A generic name for various stereo audio implementations, such as BTSC and Zweiton. |
| MTTF |
Mean Time To Failure. |
| MTTR |
Mean Time To Recovery. |
| Mu-Law |
An equation used as a T1 standard that describes the non-linear compression performed in the analog-to-digital conversion process of PCM systems used in the USA, Canada, and Japan. |
| Multi Access Connection |
A connection method whereby any number of stations can transmit to any number of other stations. |
| Multicast |
The transmission of information over the Internet to two or more users at the same time. |
| Multiframe |
A set of consecutive frames in which the position of each frame can be identified by reference to a multiframe alignment signal. The multiframe signal does not necessarily occur, in whole or in part, in each multiframe. |
| Multileaving |
The transmission of more than one data stream on the same communications channel at the same time. |
| Multilink PPP |
Multilink Point-to-Point Protocol - A protocol is a method of splitting, recombining, and sequencing datagrams across multiple logical data links. |
| Multimode Fiber |
A fiber optic transmission element which is designed to carry more than one frequency at the same time. |
| Multi-mode Laser |
A laser that produces emissions in two or more transverse or longitudinal modes. |
| Multiplexing |
A process which combines multiple network sources, creating a single stream of information to be transported over a communication line. |
| Multiport Repeater |
A repeater which collects signals from one transmission channel and, after performing the standard repeater functions, retransmits them to a number of new transmission channels. |
| Multiport Transceiver |
A transceiver which allows a number of devices to be attached to one LAN transceiver attachment on the "backbone" network. |
| MUX |
Multiplexer. |
| MVIP |
Multi-Vendor Integration Protocol - Open architecture system for merging computing technology and communications, this is commonly known as CTI. MVIP is based upon Mitel's ST Bus interface. |
