Conrad L. Young’s Wired Broadband and Related Industry Glossary of Terms with Acronyms As of 15 February 2012 Open Access This document is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial
The amount of signal in dB by which the satellite system exceeds the minimum levels required for operation. (Satnews)
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The amount of signal in dB by which the satellite system exceeds the minimum levels required for operation. (Satnews) M-ary QAM M-ary QAM modulator with square lattice. The “M” refers to the integer number of points on the QAM constellation, i.e. the number of distinct states that can exist. The size of the QAM constellation is  , where  Symbol values in each dimension are: . The bitmap is Gray encoded. Symbols are normalized so that the average energy is 1. That is, normalized with  . (Source Forge). As the order of the modulation increases, so does the number of points on the QAM constellation diagram. The various flavors of QAM may be used when data-rates beyond those offered by 8-PSK are required by a radio communications system. This is because QAM achieves a greater distance between adjacent points in the I-Q plane by distributing the points more evenly. In this way the points on the constellation are more distinct and data errors are reduced. While it is possible to transmit more bits per symbol, if the energy of the constellation is to remain the same, the points on the constellation must be closer together and the transmission becomes more susceptible to noise. This results in a higher bit error rate than for the lower order QAM variants. In this way there is a balance between obtaining the higher data rates and maintaining an acceptable bit error rate for any radio communications system. (Radio Electronics)
Mass Splicing Splicing of many fibers in a cable. (FiberOpticsInfo) Mast A ground-based structure that supports antennae at a height where they can satisfactorily send and receive radio waves. A typical mast is 15m high, and of steel lattice or tubular steel construction. New slimmer versions of masts (monopoles) can be painted to blend in with their surroundings, disguised as trees or used in conjunction with street lighting and closed circuit television (CCTV) cameras. Masts themselves play no part in the transmission of the radio waves. (TETRA) Master Antenna Television (MATV) Antenna and distribution system which serves multiple dwelling complexes such as hotels, motels and apartments. Master Headend A headend that collects television program material from various sources by satellite, microwave, fiber, and other means, and distributes this material to Distribution Hubs in the same metropolitan or regional area. A master headend MAY also perform the functions of a distribution hub for customers in its own immediate area. Master SRM Master Session Resource Manager; a device employed in a cable operator’s headend or hub, usually with switched digital video (SDV), that allocates QAM bandwidth between video on demand (VOD) and SDV services. The Master SRM enables existing VOD QAMs to be pooled and shared between VOD and SDV servers. Matching Transformer A transformer designed to match the impedance of one circuit to that of another. (Arris Glossary of Terms) Material Dispersion Dispersion resulting from the different velocities of each wavelength in a material. (FiberOpticsInfo) MATV Master Antenna Television; A distribution system that is usually contained within a single building and receives its signals from an antenna or CATV system. (Linear LLC) MBaud One million symbols of information per second. Equivalent to 1 Mbps for binary signals. (FiberOpticsInfo) MB-OFDM Multiband Orthogonal Frequency Division Multiplexing; an efficient approach for ultra-wideband (UWB) wireless communication applications. MB-OFDM is a multi-band technology, using orthogonal frequency division multiplexing. The total bandwidth that could be occupied, as defined by FCC, is from 3.1 GHz to 10.6 GHz. This covers a total span of 7.5 GHz. MB-OFDM divides the available spectrum into 14 bands of 528 MHz. The first 12 bands are grouped into 4 band groups consisting of 3 bands, and the last two bands are grouped into a fifth band group. See diagram below. An OFDM symbol, transmitted in a 528 MHz band includes 100 data sub-carriers, 10 guard sub-carriers, and 12 pilot sub-carriers for coherency and to provide robustness against frequency offsets and phase noise. Data sent over each data sub-carrier are modulated, using QPSK or dual carrier modulation (DCM). Using QPSK, a symbol of 2 bits is mapped on a sub-carrier. The DCM symbol has 4 bits. The same 4 bits of information are mapped onto two different sub-carriers, separated by 50 sub-carriers (approximately 206 MHz). With this separation, the probability that both points simultaneously suffer from fading decreases and diversity loss is reduced. 
UWB Standard Spectrum Allocation Diagram courtesy of “A MB-OFDM System Implemented in Matlab”, Revision 1.1, by Helena Sarmento, 19 July 2008 The multi-band process is done after the OFDM process above is complete. OFDM symbols are interleaved in time across multiple frequencies, based on one of two types of Time-Frequency Codes (TFCs); (1) a Time-Frequency Interleaving (TFI) code where information is interleaved over three bands, or (2) Fixed Frequency Interleaving (FFI) which allows transmission of coded data on a single band. As time progresses the OFDM symbols are transmitted on different bands: symbol 1 is transmitted on band 1, symbol 2 on band 3 and symbol 3 on band 1. (Sarmento) 
Multi Band OFDM Interleaving Diagram courtesy of “A MB-OFDM System Implemented in Matlab”, Revision 1.1, by Helena Sarmento, 19 July 2008 Mbps Megabits per second. 1,000,000 bits per second. (Arris Glossary of Terms) MC Multipoint Controller MCU Multipoint Conferencing Unit MD5 Message Digest 5 MDS An abbreviation for Multipoint Distribution Service, a band of frequencies in the United States allocated for wireless television broadcast service. (Arris Glossary of Terms) MDU Multiple Dwelling Units Mean Launched Power The average power for a continuous valid symbol sequence coupled into a fiber. (FiberOpticsInfo) Mean Time to Repair (MTTR) In cable television systems, the MTTR is the average elapsed time from the moment a loss of radio frequency (RF) channel operation is detected up to the moment the RF channel operation is fully restored. 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. (Arris Glossary of Terms) Media Access Control Address (MAC-Address) The unique hardware number assigned to network connection devices such as your computer's network card. In Ethernet, it is written as a series of six pairs of characters divided by hyphens (e.g., 00-0F-3D-50-A1-98), and is also referred to as the hardware address or adapter address. Or the “built-in” hardware address of a device connected to a shared medium. Media Access Control or Medium Access Control (MAC) The MAC sublayer is the part of the data link layer that supports topology- dependent functions and uses the services of the Physical Layer to provide services to the Logical Link Control (LLC) sublayer. Or a component of a networking software stack. In the OSI 7-layer model, the Media Access Control is a part of layer 2, the data link layer. Media Access Control Procedure (MAC-Procedure) In a subnetwork, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the data exchange between nodes. MAC procedures include framing, error protection, and acquiring the right to use the underlying transmission medium. Media Access Control Service Access Point (MSAP) The conceptual binding of a media access control (MAC) layer service provider to the protocol entities (i.e., data link layers) above it. Media Access Control Sublayer (MAC-Sublayer) The part of the datalink layer that supports topology dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer. Media Center Edition (MCE) Microsoft's operating system optimized for the presentation and distribution of digital media content (video, audio, images, etc.). Media Center Extender (MCX) Microsoft's satellite media presentation device. Any device licensed by Microsoft to connect to a media center edition (MCE) to obtain and present Windows Media Digital Rights Management (WMDRM) protected digital media content. Media Gateway (MG) A MG terminates switched circuit network (SCN) facilities (trunks, loops), packetizes the media stream, if it is not already packetized, and delivers packetized traffic to the packet network. It performs these functions in the reverse order for media streams flowing from the packet network to the SCN. Media Gateway Control Protocol (MGCP) Protocol follow-on to SGCP. Refer to IETF RFC 2705. Media Gateway Controller (MGC) An MGC is the overall controller function of the public switched telephone network (PSTN) gateway. It receives and mediates call-signaling information between the PacketCable™ and the PSTN domains, and it maintains and controls the overall call state for all calls. Medium-Power Satellite Satellite generating transmit power levels ranging from 30 to 100 watts. (Satnews) Mega A prefix for one million (1,000,000 or 106 ). (Arris Glossary of Terms) Megabit (Mb) One million bits. Megabyte (MB) A megabyte is 2 to the 20th power (220), or 1,048,576 bytes. It can be estimated as 10 to the 6th power, or one million (1,000,000) bytes. A megabyte is 1,024 kilobytes and precedes the gigabyte unit of measurement. Large computer files are typically measured in megabytes. For example, a high-quality JPEG photo from a 6.3 megapixel digital camera takes up about 3MB of space. A four minute CD-quality audio clip takes up about 40MB of space and CDs can hold up to 700MB of space. For a list of all the different units of measurements, view this Help Center article. Abbreviation: MB. (Tech Terms dot com) MegaHertz (MHz) One million cycles per second. MEMS Micro-Electrical Mechanical Systems (IEC) MEMS-Based VOA Micro-Electrical Mechanical Systems (MEMS) based variable optical attenuator; uses tuned components that can be adjusted, typically by raising or lowering them, to accomplish attenuation by partially or completely blocking a stream of light. These components can be thought of as being very similar to a mechanized camera shutter, albeit on a much smaller scale. Multiple actuators can be used to provide a very highly resolved range of attenuation; this arrangement is potentially superior to alternative optical attenuation technologies. The diagram below illustrates a MEMS-based VOA. The cylindrical items are two optical fibers; attenuation is achieved by raising a metallic shutter in the gap. As they are significantly smaller and less power hungry than competing technologies, MEMS-based devices do not require temperature compensation, which affords several advantages. Temperature control requires additional electronics, which adds cost, complexity, power consumption, and real estate requirements to the component. Temperature control requirements also typically prevent non-MEMS-based VOA components from being deployed outside the central office (CO) or other controlled, telecommunications-oriented environment. MEMS-based VOA components can be deployed in a wider variety of environments, including outside plant and access networks. Potential applications for MEMS-based components in distribution environments include amplifiers for cable television systems and gain control devices for active FTTX deployments. (IEC) 
MEMS-based VOA Diagram courtesy of D. Horsley, "Image Gallery", http://mae.ucdavis.edu/faculty/horsley/photoalbum.html MER Modulation Error Ratio; a measure of the signal-to-noise ratio (SNR) in a digitally modulated signal. Like SNR, MER is usually expressed in decibels (dB). (Zone NI ) MER over number of symbols, N is defined as: 
where  is the I component of the j-th symbol received
 is the Q component of the j-th symbol received
 is the ideal I component of the j-th symbol received and
 is the ideal Q component of the j-th symbol received.
MESFET Metal-Semiconductor Field Effect Transistor; similar to a Junction Field Effect Transistor (JFET) in construction and terminology. The difference is that instead of a using a p-n junction for a gate, a Schottky (metal-semiconductor) junction is used. MESFETs are usually constructed in GaAs, InP, or SiC (never silicon), and hence are faster but more expensive than silicon-based JFETs or MOSFETs. MESFETs are operated up to approximately 30 GHz and are commonly used for microwave frequency communications and radar. From a digital circuit design perspective, it is difficult to use MESFETs as the basis for large-scale digital integrated circuits. (Word IQ) Message Authentication Code (MAC) A fixed-length data item that is sent together with a message to ensure integrity, also known as a MIC. Message Digest 5 (MD5) A one-way hash algorithm that maps variable length plaintext into fixed-length (16 byte) ciphertext. Message Integrity Check A fixed-length data item that is sent together with a message to ensure integrity. Message Transfer Agent (MTA) A program responsible for receiving incoming messages and routing the messages to individual users. Message Transfer Part (MTP) The MTP is a set of two protocols (MTP 2, 3) within the signaling system number 7 (SS7) suite of protocols that are used to implement physical, data link, and network level transport facilities within an SS7 network. Meter Used to identify the size of a satellite or micro-wave parabolic antenna. One meter equals 3.28 feet. (Arris Glossary of Terms) 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. (FiberOpticsInfo) MFD Mode Field Diameter MG Media Gateway MGC Media Gateway Controller MGC Manual Gain Control (Arris Glossary of Terms) MGCP Media Gateway Control Protocol MH Medium-Haul; a classification of video performance under RS-250C. Higher performance than long-haul (LH) and lower performance than short-haul (SH). (FiberOpticsInfo) MHP Multimedia Home Platform MHP (Multimedia Home Platform) Connected Resource An MHP connected resource is a resource used as part of the MHP which, on its own, does not conform to the specification but which is connected to an MHP terminal in such a way that the whole is part of the MHP. MHP (Multimedia Home Platform) Solution The MHP solution encompasses the whole set of technologies necessary to implement the MHP including protocols and APIs. MHP (Multimedia Home Platform) Terminal An MHP terminal is a single piece of physical equipment conforming to the MHP specification, in particular in that it contains a Virtual Machine and an instance of the MHP API. MHz MegaHertz. One million cycles per second. (Arris Glossary of Terms) MIB Management Information Base Michelson Interferometer A Michelson interferometer, as invented by Albert Abraham Michelson, uses a single beam splitter for separating and recombining the beams. If the two mirrors are aligned for exact perpendicular incidence (see the upper figure), only one output is accessible, and the light of the other output goes back to the light source. If that optical feedback is unwanted (as is often the case with a laser, which might be destabilized), and/or access to the second output is required, the recombination of beams can occur at a somewhat different location on the beam splitter. One possibility is to use retroreflectors, as shown in the lower figure; this also has the advantage that the interferometer is fairly insensitive to slight misalignment of the retroreflectors. Alternatively, simple mirrors at slightly non-normal incidence can be used. If the path length difference is non-zero, as shown in both parts of the figure, constructive or destructive interference e.g. for the downward-directed output can be achieved only within a finite optical bandwidth. Michelson originally used a broadband light source in the famous Michelson–Morley experiment, so that he had to build an interferometer with close to zero arm length difference. There are many variations of the Michelson interferometer. For example, a Twyman–Green interferometer is essentially a Michelson interferometer illuminated with a monochromatic point source. It is used for characterizing optical elements. (Encylopedia of Laser Physics and Technology) 
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