Glossary
2-wire line. The set of two copper wires used to connect a telephone customer with a switching office, loosely wrapped around each other to minimize interference from other twisted pairs in the same bundle. Synonymous with twisted pair.
802.11. An IEEE specification for 1 Mb/s and 2 Mb/s wireless LANs.
802.11a. An IEEE specification for 54 Mb/s high rate wireless LANs in the 5 GHz band that uses orthogonal frequency division multiplexing.
802.11b. An IEEE specification for 11 Mb/s high rate wireless LANs in the 2.4 GHz band that uses direct sequence spread spectrum technology. (Also known as 802.11HR—for high rate.)
802.11g. An IEEE specification for 54 Mb/s high rate wireless LANs in the 2.4 GHz band that is backward-compatible with 802.11b, which uses the same band.
802.11n. A proposed IEEE specification for improvements in previous 801.11 wireless network specifications to achieve speeds up to 600 Mb/s.
802.16. An IEEE specification for fixed and mobile wireless connectivity offering speeds up to 120 Mb/s using the 10-66 GHz frequency range. See also Wi-MAX.
802.3. An IEEE specification for SCMA/CD based Ethernet networks.
802.5. An IEEE specification for token ring networks.
A Adaptive transform acoustic coding (ATRAC). A method of digital compression of audio signals used in the MD (MiniDisc) format. ATRAC ignores sounds out of the range of human hearing to eliminate about 80% of the data in a digital audio signal.
Addressability. The ability of a cable system to individually control its converter boxes, allowing the cable operator to enable or disable reception of channels for individual customers instantaneously from the home office.
ADSL (asymmetrical digital subscriber line). A system of compression and transmission that allows broadband signals up to 6 Mb/s to be carried over twisted pair copper wire for relatively short distances.
Advanced television (ATV). Television technologies that offer improvement in existing television systems.
AdWords. The Google service that provides short text-only advertisements on a cost-per-click basis, allowing anyone to become an advertiser on the Google site and related networks. (Yahoo! has a similar service known as Yahoo! Search Marketing.)
Agent. Any being in a virtual environment.
Algorithm. A specific formula used to modify a signal. For example, the key to a digital compression system is the algorithm that eliminates redundancy.
AM (amplitude modulation). A method of superimposing a signal on a carrier wave in which the strength (amplitude) of the carrier wave is continuously varied. AM radio and the video portion of NTSC TV signals use amplitude modulation.
American National Standards Institute (ANSI). An official body within the United States delegated with the responsibility of defining standards.
American Standard Code for Information Interchange (ASCII). Assigns specific letters, numbers, and control codes to the 256 different combinations of 0s and 1s in a byte.
Analog. A continuously varying signal or wave. As with all waves, analog waves are susceptible to interference, which can change the character of the wave.
ANSI. See American National Standards Institute.
ASCII. See American Standard Code for Information Interchange.
Aspect ratio. In visual media, the ratio of the screen width to height. Ordinary television has an aspect ratio of 4:3, while high-definition television is “wider” with an aspect ratio of 16:9 (or 5.33:3).
Asynchronous. Occurring at different times. For example, electronic mail is asynchronous communication because it does not require the sender and receiver to be connected at the same time.
ATM (asynchronous transfer mode). A method of data transport whereby fixed length packets are sent over a switched network. Speeds of up to 2 Gb/s can be achieved, making it suitable for carrying voice, video, and data.
Audio on demand. A type of media that delivers sound programs in their entirety whenever a listener requests the delivery.
Augmented reality. The superimposition of virtual objects on physical reality. For example, a technician could use augmented reality to display a 3D image of a schematic diagram on a piece of equipment to facilitate repairs.
Avatar. An animated character representing a person in a virtual environment.
B Backbone. The part of a communications network that handles the major traffic using the highest-speed, and often longest, paths in the network.
Bandwidth. A measure of capacity of communications media. Greater bandwidth allows communication of more information in a given period of time.
Bit. A single unit of data, either a one or a zero, used in digital data communications. When discussing digital data, a small “b” refers to bits, and a capital “B” refers to bytes.
Blog. Short for “Web log,” an easily updated, personal Web page allowing a user to share information, ideas, links, and media.
Bluetooth. A specification for short-range wireless technology created by a consortium of computer and communication companies that make up the Bluetooth Special Interest Group.
Blu-Ray DVD. One of two competing high-definition DVD formats.
BPL (Broadband over power lines). The use of electric power lines to provide broadband Internet access to consumers and businesses.
Bridge. A type of switch used in telephone and other networks that connects three or more users simultaneously.
Broadband. An adjective used to describe large-capacity networks that are able to carry several services at the same time, such as data, voice, and video.
Buy rate. The percentage of subscribers purchasing a pay-per-view program divided by the total number of subscribers who can receive the program.
Byte. A compilation of bits, seven bits in accordance with ASCII standards and eight bits in accordance with EBCDIC standards.
C Carrier. An electromagnetic wave or alternating current modulated to carry signals in radio, telephonic, or telegraphic transmission.
CATV (community antenna television). One of the first names for local cable television service, derived from the common antenna used to serve all subscribers.
C-band. Low-frequency (1 GHz to 10 GHz) microwave communication. Used for both terrestrial and satellite communication. C-band satellites use relatively low power and require relatively large receiving dishes.
CCD (charge coupled device). A solid-state camera pickup that converts an optical image into an electrical signal.
CCITT (International Telegraph and Telephone Consultative Committee). CCITT is the former name of the international regulatory body that defines international telecommunications and data communications standards. It has been renamed the Telecommunications Standards Sector of the International Telecommunications Union.
CDDI (copper data distributed interface). A subset of the FDDI standard targeted toward copper wiring.
CDMA (code division multiple access). A spread spectrum cellular telephone technology, which digitally modulates signals from all channels in a broad spectrum.
CD-ROM (compact disc-read only memory). The use of compact discs to store text, data, and other digitized information instead of (or in addition to) audio. One CD-ROM can store up to 700 megabytes of data.
CD-RW (compact disc-rewritable). A special type of compact disc that allows a user to record and erase data, allowing the disc to be used repeatedly.
Cell. The area served by a single cellular telephone antenna. An area is typically divided into numerous cells so that the same frequencies can be used for many simultaneous calls without interference.
Central office (CO). A telephone company facility that handles the switching of telephone calls on the public switched telephone network (PSTN) for a small regional area.
Central processing unit (CPU). The “brains” of a computer, which uses a stored program to manipulate information.
Churn. The percentage of subscribers to a service that are lost and must be replaced in a given period of time, usually a year.
Circuit-switched network. A type of network whereby a continuous link is established between a source and a receiver. Circuit switching is used for voice and video to ensure that individual parts of a signal are received in the correct order by the destination site.
CLEC. See Competitive local exchange carrier.
CO. See Central office.
Coaxial cable. A type of “pipe” for electronic signals. An inner conductor is surrounded by a neutral material, which is then covered by a metal “shield” that prevents the signal from escaping the cable.
CODEC (COmpression/DECompression). A device used to compress and decompress digital video signals.
COFDM (coded orthogonal frequency division multiplexing). A flexible protocol for advanced television signals that allows simultaneous transmission of multiple signals at the same time.
Common carrier. A business, including telephone companies and railroads, which is required to provide service to any paying customer on a first-come/first-served basis.
Competitive local exchange carrier (CLEC). An American term for a telephone company that was created after the Telecommunications Act of 1996 made it legal for companies to compete with the ILECs. Contrast with ILEC.
Compression. The process of reducing the amount of information necessary to transmit a specific audio, video, or data signal.
Cookies. A file used by a Web browser to record information about a user’s computer, including Web sites visited, which is stored on the computer’s hard drive.
Core network. The combination of telephone switching offices and transmission plant connecting switching offices together. In the U.S. local exchange network, core networks are linked by several competing interexchange networks; in the rest of the world, the core network extends to national boundaries.
CPE. See Customer premises equipment.
CPU. See Central processing unit.
Crosstalk. Interference from an adjacent channel.
Customer premises equipment (CPE). Any piece of equipment in a communication system that resides within the home or office. Examples include modems, television set-top boxes, telephones, and televisions.
Cyberspace. The artificial worlds created within computer programs.
D DBS. See Direct broadcast satellite.
Dedicated connection. A communications link that operates constantly.
Dial-up connection. A data communication link that is established when the communication equipment dials a phone number and negotiates a connection with the equipment on the other end of the link.
Digital audio broadcasting (DAB). Radio broadcasting that uses digital signals instead of analog to provide improved sound quality.
Digital audiotape (DAT). An audio recording format that stores digital information on 4mm tape.
Digital signal. A signal that takes on only two values, off or on, typically represented by a “0” or “1.” Digital signals require less power but (typically) more bandwidth than analog, and copies of digital signals are exactly like the original.
Digital subscriber line (DSL). A data communications technology that transmits information over the copper wires that make up the local loop of the public switched telephone network (see Local loop). It bypasses the circuit-switched lines that make up that network and yields much faster data transmission rates than analog modem technologies. Common varieties of DSL include ADSL, HDSL, IDSL, SDSL, and RADSL. The generic term xDSL is used to represent all forms of DSL.
Digital subscriber line access multiplexer (DSLAM). A device found in telephone company central offices that takes a number of DSL subscriber lines and concentrates them onto a single ATM line.
Digital video compression. The process of eliminating redundancy or reducing the level of detail in a video signal in order to reduce the amount of information that must be transmitted or stored.
Direct broadcast satellites (DBS). High-powered satellites designed to beam television signals directly to viewers with special receiving equipment.
Discrete multitone modulation (DMT). A method of transmitting data on copper phone wires that divides the available frequency range into 256 subchannels or tones, and which is used for some types of DSL.
Domain name system (DNS). The protocol used for assigning addresses for specific computers and computer accounts on the Internet.
Downlink. Any antenna designed to receive a signal from a communication satellite.
DSL. See Digital subscriber line.
DSLAM. See Digital subscriber line access multiplexer.
DVD (digital video or versatile disc). A plastic disc similar in size to a compact disc that has the capacity to store up to 20 times as much information as a CD and uses both sides of the disc.
DVD-RAM. A DVD that can be used to record and play back digital data (including audio and video signals).
DVD-ROM. A type of DVD that is designed to store computer programs and data for playback only.
E E-1. The European analogue to T1, a standard, high-capacity telephone circuit capable of transmitting approximately 2 Mb/s or the equivalent of 30 voice channels.
Echo cancellation. The elimination of reflected signals (“echoes”) in a two-way transmission created by some types of telephone equipment; used in data transmission to improve the bandwidth of the line.
Electromagnetic spectrum. The set of electromagnetic frequencies that includes radio waves, microwave, infrared, visible light, ultraviolet rays, and gamma rays. Communication is possible through the electromagnetic spectrum by radiation and reception of radio waves at a specific frequency.
E-mail. Electronic mail or textual messages sent and received through electronic means.
EV-DO. Short for “Evolution Data Optimized,” an emerging standard for the transmission of data over cellular telephone networks at speeds up to 500 Kb/s.
Extranet. A special type of Intranet that allows selected users outside an organization to access information on a company’s Intranet.
F FDDI-I (fiber data distributed interface I). A standard for 100 Mb/s LANs using fiber optics as the network medium linking devices.
FDDI-II (fiber data distributed interface II). Designed to accommodate the same speeds as FDDI-I, but over a twisted-pair copper cable.
Federal Communications Commission (FCC). The U.S. federal government organization responsible for the regulation of broadcasting, cable, telephony, satellites, and other communications media.
Fiber-in-the-loop (FITL). The deployment of fiber optic cable in the local loop, which is the area between the telephone company’s central office and the subscriber.
Fiber optics. Thin strands of ultrapure glass or plastic used to carry light waves from one location to another.
Fiber-to-the-cabinet (FTTCab). Network architecture where an optical fiber connects the telephone switch to a street-side cabinet. The signal is converted to feed the subscriber over a twisted copper pair.
Fiber-to-the-curb (FTTC). The deployment of fiber optic cable from a central office to a platform serving numerous homes. The home is linked to this platform with coaxial cable or twisted pair (copper wire). Each fiber carries signals for more than one residence, lowering the cost of installing the network versus fiber-to-the-home.
Fiber-to-the-home (FTTH). The deployment of fiber optic cable from a central office to an individual home. This is the most expensive broadband network design, with every home needing a separate fiber optic cable to link it with the central office.
Fiber-to-the-node (FTTN). The deployment of fiber optic cable from a central office to neighborhood, where one connection serves a number of houses.
Fixed satellite services (FSS). The use of geosynchronous satellites to relay information to and from two or more fixed points on the earth’s surface.
FM (frequency modulation). A method of superimposing a signal on a carrier wave in which the frequency on the carrier wave is continuously varied. FM radio and the audio portion of an NTSC television signal use frequency modulation.
Footprint. The coverage area of a satellite signal, which can be focused to cover specific geographical areas.
Frame. One complete still image that makes up a part of a video signal.
Frame relay. A high-speed packet switching protocol used in wide area networks (WANs), often to connect local area networks (LANs) to each other, with a maximum bandwidth of 44.725 Mb/s.
Frequency. The number of oscillations in an alternating current that occur within one second, measured in Hertz (Hz).
Frequency division multiplexing (FDM). The transmission of multiple signals simultaneously over a single transmission path by dividing the available bandwidth into multiple channels that each cover a different range of frequencies.
FTP (file transfer protocol). An Internet application that allows a user to download and upload programs, documents, and pictures to and from databases virtually anywhere on the Internet.
FTTC. See Fiber-to-the-curb.
FTTH. See Fiber-to-the-home.
FTTN. See Fiber-to-the-node.
Full-motion video. The projection of 20 or more frames (or still images) per second to give the eye the perception of movement. Broadcast video in the United States uses 30 frames per second, and most film technologies use 24 frames per second.
Fuzzy logic. A method of design that allows a device to undergo a gradual transition from on to off, instead of the traditional protocol of all-or-nothing.
G G.dmt. A kind of asymmetric DSL technology, based on DMT modulation, offering up to 8 Mb/s downstream bandwidth, 1.544 Mb/s upstream bandwidth. “G.dmt” is actually a nickname for the standard officially known as ITU-T Recommendation G.992.1. (See International Telecommunications Union.)
G.lite [pronounced “G-dot-light”]. A kind of asymmetric DSL technology, based on DMT modulation, that offers up to 1.5 Mb/s downstream bandwidth, 384 Kb/s upstream, does not usually require a splitter, and is easier to install than other types of DSL. “G.lite” is a nickname for the standard officially known as G.992.2. (See International Telecommunications Union.)
Geosynchronous orbit (GEO, also known as geostationary orbit). A satellite orbit directly above the equator at 22,300 miles. At that distance, a satellite orbits at a speed that matches the revolution of the earth so that, from the earth, the satellite appears to remain in a fixed position.
Gigabyte. 1,000,000,000 bytes or 1,000 megabytes (see Byte).
Global positioning system (GPS). Satellite-based services that allow a receiver to determine its location within a few meters anywhere on earth.
Gopher. An early Internet application that assisted users in finding information on and accessing the resources of remote computers.
Graphical user interface (GUI). A computer operating system that is based on icons and visual relationships rather than text. Windows and the Macintosh computer use GUIs because they are more user friendly.
Groupware. Computer software applications that facilitates intraorganizational communication, allowing multiple users to access and change files, send and receive e-mail, and keep track of progress on group projects.
GSM (Group standard mobile). A type of digital cellular telephony used in Europe that uses time-division multiplexing to carry multiple signals in a single frequency.
GUI. See Graphical user interface.
H Hardware. The physical equipment related to a technology.
HD-DVD. One of two competing high-definition DVD formats.
HD Radio. The marketing term used for digital radio broadcasting in the U.S. (See IBOC.)
HDSL. See High bit-rate digital subscriber line.
Hertz. See Frequency.
HFC (hybrid fiber/coax). A type of network that includes a fiber optic “backbone” to connect individual nodes and coaxial cable to distribute signals from an optical network interface to the individual users (up to 500 or more) within each node.
High bit-rate digital subscriber line (HDSL). A symmetric DSL technology that provides a maximum bandwidth of 1.5 Mb/s in each direction over two phone lines, or 2 Mb/s over three phone lines.
High bit-rate digital subscriber line II (HDSL II). A descendant of HDSL that offers the same performance over a single phone line.
High-definition television (HDTV). Any television system that provides a significant improvement in existing television systems. Most HDTV systems offer more than 1,000 scan lines, in a wider aspect ratio, with superior color and sound fidelity.
Hologram. A three-dimensional photographic image made by a reflected laser beam of light on a photographic film.
Home networking. Connecting different electronic devices in a household by way of a local area network (LAN).
Hotspot. An area in which wireless, public Internet access is available using one or more of the Wi-Fi protocols.
HTML. See Hypertext markup language.
http (hypertext transfer protocol). The first part of an address (URL) of a site on the Internet, signifying a document written in hypertext markup language (HTML).
Hybrid fiber/coax (HFC). A type of network that includes coaxial cables to distribute signals to a group of individual locations (typically 500 or more) and a fiber optic backbone to connect these groups.
Hypertext. Documents or other information with embedded links that enable a reader to access tangential information at programmed points in the text.
Hypertext markup language (HTML). The computer language used to create hypertext documents, allowing connections from one document or Internet page to numerous others.
Hz. An abbreviation for Hertz. See Frequency.
I IBOC (In-band, on-channel). The transmission system for digital broadcasting in the U.S. that incorporates a digital radio signal on the same transmission frequency used for analog broadcasting.
ILEC. See Incumbent local exchange carrier.
Image stabilizer. A feature in camcorders that lessens the shakiness of the picture either optically or digitally.
Incumbent local exchange carrier (ILEC). A large telephone company that has been providing local telephone service in the United States since the divestiture of the AT&T telephone monopoly in 1982.
Institute of Electrical & Electronics Engineers (IEEE). A membership organization comprised of engineers, scientists, and students that sets standards for computers and communications.
Instructional Television Fixed Service (ITFS). A microwave television service designed to provide closed-circuit educational programming. Underutilization of these frequencies led wireless cable (MMDS) operators to obtain FCC approval to lease these channels to deliver television programming to subscribers.
Interactive TV (ITV). A television system in which the user interacts with the program.
Interexchange carrier. Any company that provides interLATA (long distance) telephone service.
Interlaced scanning. The process of displaying an image using two scans of a screen, with the first providing all the even-numbered lines and the second providing the odd-numbered lines.
International Organization of Standardization (ISO). Develops, coordinates, and promulgates international standards that facilitate world trade.
Internet Engineering Task Force (IETF). The standards organization that standardizes most Internet communication protocols, including Internet protocol (IP) and hypertext transfer protocol (HTTP).
Internet service provider (ISP). An organization offering and providing Internet access to the public using computer servers connected directly to the Internet.
Intranet. A network serving a single organization or site that is modeled after the Internet, allowing users access to almost any information available on the network. Unlike the Internet, Intranets are typically limited to one organization or one site, with little or no access to outside users.
IP (Internet protocol). The standard for adding “address” information to data packets to facilitate the transmission of these packets over the Internet.
IPTV (Internet protocol television). The distribution of television programming over the Internet or other network through the use of Internet protocol packet switching.
ISDN (Integrated Services Digital Network). A planned hierarchy of digital switching and transmission systems synchronized to transmit all signals in digital form, offering increased capacity over analog networks.
ISO. See International Organization of Standardization.
ISP. See Internet service provider.
ITU (International Telecommunications Union). A U.N. organization that coordinates use of the spectrum and creation of technical standards for communication equipment.
J JPEG (Joint Photographic Experts Group). A committee formed by the ISO to create a digital compression standard for still images. Also refers to the digital compression standard for still images created by this group.
K Killer app. Short for “killer application,” this is a function of a new technology that is so strongly desired by users that it results in adoption of the technology.
Kilobit. One thousand bits (see Bit).
Kilobyte. 1,000 bytes (see Byte).
Ku-band. A set of microwave frequencies (12 GHz to 14 GHz) used exclusively for satellite communication. Compared to C-band, the higher frequencies produce shorter waves and require smaller receiving dishes.
L LAN. See Local area network.
Laser. From the acronym for “light amplification by stimulated emission of radiation.” A laser usually consists of a light-amplifying medium placed between two mirrors. Light not perfectly aligned with the mirrors escapes out the sides, but light perfectly aligned will be amplified. One mirror is made partially transparent. The result is an amplified beam of light that emerges through the partially transparent mirror.
Last mile. See Local loop.
LATA (local access transport area). The geographical areas defining local telephone service. Any call within a LATA is handled by the local telephone company, but calls between LATAs must be handled by long distance companies, even if the same local telephone company provides service in both LATAs.
LEO (low earth orbit). A satellite orbit between 400 and 800 miles above the earth’s surface. The close proximity of the satellite reduces the power needed to reach the satellite, but the fact that these satellites complete an entire orbit in a few hours means that a large number of satellites must be used in a LEO satellite system in order to have one overhead at all times.
Liner notes. The printed material that accompanies a CD or record album, including authors, identification of musicians, lyrics, pictures, and commentary.
LMDS (local multipoint distribution service). A new form of wireless technology similar to MMDS that uses frequencies above 28 GHz.
Local area network (LAN). A network connecting a number of computers to each other or to a central server so that computers can share programs and files.
Local exchange carrier (LEC). A local telephone company.
Local loop. The copper lines between a customer’s premises and a telephone company’s central office (see Central office).
M Mb/s. Megabits per second.
M-commerce. Mobile commerce—the use of cellular telephones and other wireless mobile devices to buy and sell goods and services.
Megabit. One million bits.
Megabyte. 1,000,000 bytes or 1,000 kilobytes (see Byte).
Megapixel. Refers to one million pixels, and is used as a measure of the quality of digital cameras. The more pixels used for a picture, the higher the quality.
Microcell. The area, typically a few hundred yards across, served by a single transmitter in a PCS network. The use of microcells allows the reuse of the same frequencies many times in an area, allowing more simultaneous users.
MIDI (musical instrument digital interface). An international standard for representing music in digital form. Music can be directly input from a computer keypad and stored to disc or RAM, then played back through a connected instrument. Conversely, a song can be played by the performer on an instrument interfaced with the computer.
MIPS (millions of instructions per second). This is a common measure of the speed of a computer processor.
MMDS (multichannel multipoint distribution systems). A service similar to cable television that uses microwaves to distribute the signals instead of coaxial cable. MMDS is therefore better suited to sparsely-populated areas than cable.
Mobile satellite services (MSS). The use of satellites to provide navigation services and to connect vehicles and remote regions with other mobile or stationary units.
Modem (MOdulator/DEModulator). Enables transmission of a digital signal, such as that generated by a computer, over an analog network, such as the telephone network.
Monochromatic. Light or other radiation with one single frequency or wavelength. Since no light is perfectly monochromatic, the term is used loosely to describe any light of a single color over a very narrow band of wavelengths.
MPEG (Moving Picture Experts Group). A committee formed by the ISO to set standards for digital compression of full-motion video. Also stands for the digital compression standard created by the committee that produces VHS-quality video.
MPEG-1. An international standard for the digital compression of VHS-quality, full-motion video.
MPEG-2. An international standard for the digital compression of broadcast-quality, full-motion video.
MTSO (mobile telephone switching office). The “heart” of a cellular telephone network, containing switching equipment and computers to manage the use of cellular frequencies and connect cellular telephone users to the landline network.
Multicast. The transmission of information over the Internet to two or more users at the same time.
Multimedia. The combination of video, audio, and text in a single platform or presentation.
Multiple system operator (MSO). A cable company that owns and operates many local cable systems.
Multiplexing. Transmitting several messages or signals simultaneously over the same circuit or frequency.
Must-carry. A set of rules requiring cable operators to carry all local broadcast television stations.
MVPD (Multichannel video programming distributor). A generic term used to refer to services such as cable television, DBS, etc. that offer a full range of television programming services.
N Nanometer. One billionth of a meter. Did you know that “nano” comes from the Greek word “dwarf?”
Narrowband. A designation of bandwidth less than 56 Kb/s.
National information infrastructure (NII). An initiative to support the private sector construction and maintenance of a “seamless web” of communication networks, computers, databases, and consumer electronics that will put vast amounts of information at users’ fingertips.
Near video on demand (NVOD). A pay-per-view service offering movies on up to eight channels, each with staggered start times so that a viewer can watch one at any time. NVOD is much more flexible than PPV, and costs far less than VOD to implement.
Network access provider (NAP). Another name for a provider of networked telephone and associated services, usually in the United States.
Network service provider (NSP). A high-level Internet provider that offers high-speed backbone services.
Newbies. New users of an interactive technology, usually identified because they have not yet learned the etiquette of communication in a system.
Nodes. Routers or switches on a broadband network that provide a link from point A to point B across a network.
NTSC (National Television Standards Committee). The group responsible for setting the U.S. standards for color television in the 1950s.
O OCR (optical character recognition). Refers to computer programs that can convert images of text to text that can be edited.
Octet. A byte, more specifically, an eight-bit byte. The origins of the octet trace back to when different networks had different byte sizes. Octet was coined to identify the eight-bit byte size.
Operating system. The program embedded in most computers that controls the manner in which data are read, processed, and stored.
Optical carrier 3 (OC3). A fiber optic line carrying 155 Mb/s, a U.S. designation generally recognized throughout the telecommunications community worldwide.
Optical network unit (ONU). A form of access node that converts optical signals transmitted via fiber to electrical signals that can be transmitted via coaxial cable or twisted pair copper wiring to individual subscribers. See Hybrid fiber/coax.
Overlay. The process of combining a graphic with an existing video image.
P Packet switched networks. A network that allows a message to be broken into small “packets” of data that are sent separately by a source to the destination. The packets may travel different paths and arrive at different times, with the destination site reassembling them into the original message. Packet switching is used in most computer networks because it allows a very large amount of information to be transmitted through a limited bandwidth.
Passive optical network (PON). A fiber-based transmission network with no active electronics.
PCN (personal communications network). Similar to PCS, but incorporating a wider variety of applications including voice, data, and facsimile.
PCS (personal communications services). A new category of digital cellular telephone service which uses much smaller service areas (microcells) than ordinary cellular telephony.
Peripheral. An external device that increases the capabilities of a communications system.
Personal digital assistants (PDAs). Extremely small computers (usually about half the size of a notebook) designed to facilitate communication and organization. A typical PDA accepts input from a special pen instead of a keyboard, and includes appointment and memo applications. Some PDAs also include fax software and a cellular telephone modem to allow faxing of messages almost anywhere.
Photovoltaic cells. A device that converts light energy to electricity.
Pixel. The smallest element of a computer display. The more pixels in a display, the greater the resolution.
Point of presence (POP). The physical point of connection between a data network and a telephone network.
Point-to-multipoint service. A communication technology designed for broadcast communication, where one sender simultaneously sends a message to an unlimited number of receivers.
Point-to-point service. A communication technology designed for closed-circuit communication between two points such as in a telephone circuit.
POTS (plain old telephone service). An acronym identifying the traditional function of a telephone network to allow voice communication between two people across a distance.
POTS splitter. A device that uses filters to separate voice from data signals when they are to be carried on the same phone line. Required for several types of DSL service.
PPV (pay-per-view). A television service in which the subscriber is billed for individual programs or events.
Progressive scanning. A video display system that sequentially scans all the lines in a video display.
PTT. A government organization that offers telecommunications services within a country. (The initials refer to the antecedents of modern communication: the post [mail], telephone, and telegraph.)
Q QuickTime. A computer video playback system that enables a computer to automatically adjust video frame rates and image resolution so that sound and motion are synchronized during playback.
R RBOC (regional Bell operating company). One of the seven local telephone companies formed upon the divestiture of AT&T in 1984. The original seven were Bell Atlantic, NYNEX, Pacific Telesis, BellSouth, Southwestern Bell, U S WEST, and Ameritech.
Retransmission consent. The right of a television station to prohibit retransmission of its signal by a cable company. Under the 1992 Cable Act, U.S. television stations may choose between must-carry and retransmission consent.
RF (radio frequency). Electromagnetic carrier waves upon which audio, video, or data signals can be superimposed for transmission.
Roaming. Movement of a wireless node between two microcells.
Router. The central switching device that directs and controls the flow of data through the computer network.
RSS (real simple syndication). An Internet application that tells a Web site or a special computer program that new information is available to download, “pushing” information to the user, rather than waiting for the user to request it.
S SCMS (Serial Copy Management System). A method of protecting media content from piracy that allows copies to be made of a specific piece of content, but will not allow copies of copies.
SCSI (small computer system interface) [pronounced “scuzzy”]. An outmoded type of interface between computers and peripherals.
SDTV (standard-definition television). Digital television transmissions that deliver approximately the same resolution and aspect ratio of traditional television broadcasts, but do so in a fraction of the bandwidth through the use of digital video compression.
SMPTE (Society of Motion Picture and Television Engineers). The industry group responsible for setting technical standards in most areas of film and television production.
Social Networking. The use of the Internet and other electronic media to allow individuals to create groups and communities for the sharing of information, entertainment, and activities.
Software. The messages transmitted or processed through a communications medium. This term also refers to the instructions (programs) written for programmable computers.
SONET (Synchronous Optical Network). A standard for data transfer over fiber optic networks used in the United States that can be used with a wide range of packet- and circuit-switched technologies.
Spot beam. A satellite signal targeted at a small area, or footprint. By concentrating the signal in a smaller area, the signal strength increases in the reception area.
SVOD (subscription video on demand). A pay television service that offers a range of VOD (video on demand) programming for a monthly fee.
Symmetric digital subscriber line (SDSL). A DSL technology that provides a maximum bandwidth of 1.5 Mb/s using one phone line, with a downstream transmission rate that equals the upstream transmission rate and allows use of POTS service on the same phone line. SDSL also refers to single-line digital subscriber line.
Synchronous transmission. The transmission of data at a fixed rate, based on a master clock, between the transmitter and receiver.
T T-commerce. Television commerce—the use of interactive television to buy and sell goods and services.
T1. A standard for physical wire cabling used in networks. A T-1 line has the bandwidth of 1.54 Mb/s.
T3. A standard for physical wire cabling that has the bandwidth of 44.75 Mb/s.
TCP/IP (transmission control protocol/Internet protocol). A method of packet-switched data transmission used on the Internet. The protocol specifies the manner in which a signal is divided into parts, as well as the manner in which “address” information is added to each packet to ensure that it reaches its destination and can be reassembled into the original message.
TDMA (time division multiple access). A cellular telephone technology that sends several digital signals over a single channel by assigning each signal a periodic slice of time on the channel. Different TDMA technologies include North America’s Interim Standard (IS) 54, Europe’s global system for mobile communications, and a version developed by InterDigital Corporation. These systems differ in circuits per channel, timing, and channel width.
Telecommuting. The practice of using telecommunications technologies to facilitate work at a site away from the traditional office location and environment.
Teleconference. Interactive, electronic communication among three or more people at two or more sites. Includes audio-only, audio and graphics, and videoconferencing.
Teleport. A site containing multiple satellite uplinks and downlinks, along with microwave, fiber optic, and other technologies to facilitate the distribution of satellite signals.
Terabyte. 1,000,000,000,000 bytes or 1,000 gigabytes (see Byte).
Time division multiplexing (TDM). The method of multiplexing where each device on the network is provided with a set amount of link time.
Transponder. The part of a satellite that receives an incoming signal from an uplink and retransmits it on a different frequency to a downlink.
TVRO (television receive only). A satellite dish used to receive television signals from a satellite.
Twisted pair. The set of two copper wires used to connect a telephone customer with a switching office. The bandwidth of twisted pair is extremely small compared with coaxial cable or fiber optics.
U UGC (User generated content). Media content that is created by consumers for distribution to other consumers, either directly or through media channels.
UHF (ultra high frequency). Television channels numbered 14 through 83.
Ultra-high definition television. An experimental television format developed by NHK offering approximately 16 times the detail found in high-definition television. The format has 4320 scan lines, with a resolution of 7680 pixels per line.
Universal ADSL Working Group (UAWG). An organization composed of leading personal computer industry, networking, and telecommunications companies with the goal of creating an interoperable, consumer-friendly ADSL standard entitled the G.992.2 standard, and commonly referred to as the G.lite standard.
Universal serial bus (USB). A computer interface with a maximum bandwidth of 1.5 Mb/s used for connecting computer peripherals such as printers, keyboards, and scanners.
Universal service provider (USP). A company that sells access to phone, data, and entertainment services and networks.
Universal service. In telecommunications policy, the principle that an interactive telecommunications service must be available to everyone within a community in order to increase the utility and value of the network for all users.
Uplink. An antenna that transmits a signal to a satellite for relay back to earth.
URL (uniform resource locator). An “address” for a specific page on the Internet. Every page has a URL that specifies its server and file name.
V Variable bit rate (VBR). Data transmission that can be represented by an irregular grouping of bits or cell payloads followed by unused bits or cell payloads. Most applications other than voice circuits generate VBR traffic patterns.
VDSL (Very high bit-rate digital subscriber line). An asymmetric DSL that delivers from 13 Mb/s to 52 Mb/s downstream bandwidth and 1.5 Mb/s to 2.3 Mb/s upstream.
Vertical blanking interval (VBI). In an NTSC television signal, the portion of the signal that is not displayed on a television receiver. Some of the lines in the VBI contain “sync” information that is used to identify the beginning of a new picture. Some of the blank lines in the VBI can be used to carry data such as closed captions.
Vertical integration. The ownership of more than one function of production or distribution by a single company, so that the company, in effect, becomes its own customer.
VHF (very high frequency). Television channels numbered 2 through 13.
Videoconference. Interactive audio/visual communication among three or more people at two or more sites.
Video on demand (VOD). A pay-per-view television service in which a viewer can order a program from a menu and have it delivered instantly to the television, typically with the ability to pause, rewind, etc.
Videophone. A telephone that provides both sound (audio) and picture (video).
Videotext (also known as videotex). An interactive computer system using text and/or graphics that allows access to a central computer using a terminal or personal computer to engage in data retrieval, communication, transactions, and/or games.
Virtual reality (VR). A cluster of interactive technologies that gives users a compelling sense of being inside a circumambient environment created by a computer.
Vlog. A video blog.
VoIP (Voice over Internet Protocol). A set of standards designed to enable telephone communications over data networks using packet-based switching (as opposed to circuit-based switching used in traditional telephone networks.
VRML (virtual reality markup language). A computer language that provides a three-dimensional environment for traditional Internet browsers, resulting in a simple form of virtual reality available over the Internet.
VSAT (very small aperture terminal). A satellite system that uses relatively small satellite dishes to send and receive one- or two-way data, voice, or even video signals.
W Web Services. The name given to the set of protocols including XML, SOAP, and J2EE that facilitate sharing of information across programs and platforms, allowing interconnection of disparate databases.
Wide area network (WAN). A network that interconnects geographically distributed computers or LANs.
Wi-Fi. A collective term for a set of wireless data standards offering speeds up to 54 Mb/s, including 802.11a, 802.11b, and 802.11g.
Wiki. Internet content or Web sites that consist of content is created and edited by the users of the content.
Wi-MAX. Another name for the IEEE standard 802.16, which consists of a set of standards for fixed and mobile wireless data communication offering speeds of up to 120 Mb/s in the 10-66 GHz frequency range.
Wireless cable. See MMDS.
Wireless node. A user computer with a wireless network interface card.
WORM (write once, read many). A technique that allows recording of information on a medium only once, with unlimited playback.
X X.25 data protocol. A packet switching standard developed in the mid-1970s for transmission of data over twisted-pair copper wire.
xDSL. See Digital subscriber line.
XML. (Extensible markup language). A protocol used to code information in a computer program so that information can be shared across numerous programs and platforms.
2-wire line. The set of two copper wires used to connect a telephone customer with a switching office, loosely wrapped around each other to minimize interference from other twisted pairs in the same bundle. Synonymous with twisted pair.
802.11. An IEEE specification for 1 Mb/s and 2 Mb/s wireless LANs.
802.11a. An IEEE specification for 54 Mb/s high rate wireless LANs in the 5 GHz band that uses orthogonal frequency division multiplexing.
802.11b. An IEEE specification for 11 Mb/s high rate wireless LANs in the 2.4 GHz band that uses direct sequence spread spectrum technology. (Also known as 802.11HR—for high rate.)
802.11g. An IEEE specification for 54 Mb/s high rate wireless LANs in the 2.4 GHz band that is backward-compatible with 802.11b, which uses the same band.
802.11n. A proposed IEEE specification for improvements in previous 801.11 wireless network specifications to achieve speeds up to 600 Mb/s.
802.16. An IEEE specification for fixed and mobile wireless connectivity offering speeds up to 120 Mb/s using the 10-66 GHz frequency range. See also Wi-MAX.
802.3. An IEEE specification for SCMA/CD based Ethernet networks.
802.5. An IEEE specification for token ring networks.
A Adaptive transform acoustic coding (ATRAC). A method of digital compression of audio signals used in the MD (MiniDisc) format. ATRAC ignores sounds out of the range of human hearing to eliminate about 80% of the data in a digital audio signal.
Addressability. The ability of a cable system to individually control its converter boxes, allowing the cable operator to enable or disable reception of channels for individual customers instantaneously from the home office.
ADSL (asymmetrical digital subscriber line). A system of compression and transmission that allows broadband signals up to 6 Mb/s to be carried over twisted pair copper wire for relatively short distances.
Advanced television (ATV). Television technologies that offer improvement in existing television systems.
AdWords. The Google service that provides short text-only advertisements on a cost-per-click basis, allowing anyone to become an advertiser on the Google site and related networks. (Yahoo! has a similar service known as Yahoo! Search Marketing.)
Agent. Any being in a virtual environment.
Algorithm. A specific formula used to modify a signal. For example, the key to a digital compression system is the algorithm that eliminates redundancy.
AM (amplitude modulation). A method of superimposing a signal on a carrier wave in which the strength (amplitude) of the carrier wave is continuously varied. AM radio and the video portion of NTSC TV signals use amplitude modulation.
American National Standards Institute (ANSI). An official body within the United States delegated with the responsibility of defining standards.
American Standard Code for Information Interchange (ASCII). Assigns specific letters, numbers, and control codes to the 256 different combinations of 0s and 1s in a byte.
Analog. A continuously varying signal or wave. As with all waves, analog waves are susceptible to interference, which can change the character of the wave.
ANSI. See American National Standards Institute.
ASCII. See American Standard Code for Information Interchange.
Aspect ratio. In visual media, the ratio of the screen width to height. Ordinary television has an aspect ratio of 4:3, while high-definition television is “wider” with an aspect ratio of 16:9 (or 5.33:3).
Asynchronous. Occurring at different times. For example, electronic mail is asynchronous communication because it does not require the sender and receiver to be connected at the same time.
ATM (asynchronous transfer mode). A method of data transport whereby fixed length packets are sent over a switched network. Speeds of up to 2 Gb/s can be achieved, making it suitable for carrying voice, video, and data.
Audio on demand. A type of media that delivers sound programs in their entirety whenever a listener requests the delivery.
Augmented reality. The superimposition of virtual objects on physical reality. For example, a technician could use augmented reality to display a 3D image of a schematic diagram on a piece of equipment to facilitate repairs.
Avatar. An animated character representing a person in a virtual environment.
B Backbone. The part of a communications network that handles the major traffic using the highest-speed, and often longest, paths in the network.
Bandwidth. A measure of capacity of communications media. Greater bandwidth allows communication of more information in a given period of time.
Bit. A single unit of data, either a one or a zero, used in digital data communications. When discussing digital data, a small “b” refers to bits, and a capital “B” refers to bytes.
Blog. Short for “Web log,” an easily updated, personal Web page allowing a user to share information, ideas, links, and media.
Bluetooth. A specification for short-range wireless technology created by a consortium of computer and communication companies that make up the Bluetooth Special Interest Group.
Blu-Ray DVD. One of two competing high-definition DVD formats.
BPL (Broadband over power lines). The use of electric power lines to provide broadband Internet access to consumers and businesses.
Bridge. A type of switch used in telephone and other networks that connects three or more users simultaneously.
Broadband. An adjective used to describe large-capacity networks that are able to carry several services at the same time, such as data, voice, and video.
Buy rate. The percentage of subscribers purchasing a pay-per-view program divided by the total number of subscribers who can receive the program.
Byte. A compilation of bits, seven bits in accordance with ASCII standards and eight bits in accordance with EBCDIC standards.
C Carrier. An electromagnetic wave or alternating current modulated to carry signals in radio, telephonic, or telegraphic transmission.
CATV (community antenna television). One of the first names for local cable television service, derived from the common antenna used to serve all subscribers.
C-band. Low-frequency (1 GHz to 10 GHz) microwave communication. Used for both terrestrial and satellite communication. C-band satellites use relatively low power and require relatively large receiving dishes.
CCD (charge coupled device). A solid-state camera pickup that converts an optical image into an electrical signal.
CCITT (International Telegraph and Telephone Consultative Committee). CCITT is the former name of the international regulatory body that defines international telecommunications and data communications standards. It has been renamed the Telecommunications Standards Sector of the International Telecommunications Union.
CDDI (copper data distributed interface). A subset of the FDDI standard targeted toward copper wiring.
CDMA (code division multiple access). A spread spectrum cellular telephone technology, which digitally modulates signals from all channels in a broad spectrum.
CD-ROM (compact disc-read only memory). The use of compact discs to store text, data, and other digitized information instead of (or in addition to) audio. One CD-ROM can store up to 700 megabytes of data.
CD-RW (compact disc-rewritable). A special type of compact disc that allows a user to record and erase data, allowing the disc to be used repeatedly.
Cell. The area served by a single cellular telephone antenna. An area is typically divided into numerous cells so that the same frequencies can be used for many simultaneous calls without interference.
Central office (CO). A telephone company facility that handles the switching of telephone calls on the public switched telephone network (PSTN) for a small regional area.
Central processing unit (CPU). The “brains” of a computer, which uses a stored program to manipulate information.
Churn. The percentage of subscribers to a service that are lost and must be replaced in a given period of time, usually a year.
Circuit-switched network. A type of network whereby a continuous link is established between a source and a receiver. Circuit switching is used for voice and video to ensure that individual parts of a signal are received in the correct order by the destination site.
CLEC. See Competitive local exchange carrier.
CO. See Central office.
Coaxial cable. A type of “pipe” for electronic signals. An inner conductor is surrounded by a neutral material, which is then covered by a metal “shield” that prevents the signal from escaping the cable.
CODEC (COmpression/DECompression). A device used to compress and decompress digital video signals.
COFDM (coded orthogonal frequency division multiplexing). A flexible protocol for advanced television signals that allows simultaneous transmission of multiple signals at the same time.
Common carrier. A business, including telephone companies and railroads, which is required to provide service to any paying customer on a first-come/first-served basis.
Competitive local exchange carrier (CLEC). An American term for a telephone company that was created after the Telecommunications Act of 1996 made it legal for companies to compete with the ILECs. Contrast with ILEC.
Compression. The process of reducing the amount of information necessary to transmit a specific audio, video, or data signal.
Cookies. A file used by a Web browser to record information about a user’s computer, including Web sites visited, which is stored on the computer’s hard drive.
Core network. The combination of telephone switching offices and transmission plant connecting switching offices together. In the U.S. local exchange network, core networks are linked by several competing interexchange networks; in the rest of the world, the core network extends to national boundaries.
CPE. See Customer premises equipment.
CPU. See Central processing unit.
Crosstalk. Interference from an adjacent channel.
Customer premises equipment (CPE). Any piece of equipment in a communication system that resides within the home or office. Examples include modems, television set-top boxes, telephones, and televisions.
Cyberspace. The artificial worlds created within computer programs.
D DBS. See Direct broadcast satellite.
Dedicated connection. A communications link that operates constantly.
Dial-up connection. A data communication link that is established when the communication equipment dials a phone number and negotiates a connection with the equipment on the other end of the link.
Digital audio broadcasting (DAB). Radio broadcasting that uses digital signals instead of analog to provide improved sound quality.
Digital audiotape (DAT). An audio recording format that stores digital information on 4mm tape.
Digital signal. A signal that takes on only two values, off or on, typically represented by a “0” or “1.” Digital signals require less power but (typically) more bandwidth than analog, and copies of digital signals are exactly like the original.
Digital subscriber line (DSL). A data communications technology that transmits information over the copper wires that make up the local loop of the public switched telephone network (see Local loop). It bypasses the circuit-switched lines that make up that network and yields much faster data transmission rates than analog modem technologies. Common varieties of DSL include ADSL, HDSL, IDSL, SDSL, and RADSL. The generic term xDSL is used to represent all forms of DSL.
Digital subscriber line access multiplexer (DSLAM). A device found in telephone company central offices that takes a number of DSL subscriber lines and concentrates them onto a single ATM line.
Digital video compression. The process of eliminating redundancy or reducing the level of detail in a video signal in order to reduce the amount of information that must be transmitted or stored.
Direct broadcast satellites (DBS). High-powered satellites designed to beam television signals directly to viewers with special receiving equipment.
Discrete multitone modulation (DMT). A method of transmitting data on copper phone wires that divides the available frequency range into 256 subchannels or tones, and which is used for some types of DSL.
Domain name system (DNS). The protocol used for assigning addresses for specific computers and computer accounts on the Internet.
Downlink. Any antenna designed to receive a signal from a communication satellite.
DSL. See Digital subscriber line.
DSLAM. See Digital subscriber line access multiplexer.
DVD (digital video or versatile disc). A plastic disc similar in size to a compact disc that has the capacity to store up to 20 times as much information as a CD and uses both sides of the disc.
DVD-RAM. A DVD that can be used to record and play back digital data (including audio and video signals).
DVD-ROM. A type of DVD that is designed to store computer programs and data for playback only.
E E-1. The European analogue to T1, a standard, high-capacity telephone circuit capable of transmitting approximately 2 Mb/s or the equivalent of 30 voice channels.
Echo cancellation. The elimination of reflected signals (“echoes”) in a two-way transmission created by some types of telephone equipment; used in data transmission to improve the bandwidth of the line.
Electromagnetic spectrum. The set of electromagnetic frequencies that includes radio waves, microwave, infrared, visible light, ultraviolet rays, and gamma rays. Communication is possible through the electromagnetic spectrum by radiation and reception of radio waves at a specific frequency.
E-mail. Electronic mail or textual messages sent and received through electronic means.
EV-DO. Short for “Evolution Data Optimized,” an emerging standard for the transmission of data over cellular telephone networks at speeds up to 500 Kb/s.
Extranet. A special type of Intranet that allows selected users outside an organization to access information on a company’s Intranet.
F FDDI-I (fiber data distributed interface I). A standard for 100 Mb/s LANs using fiber optics as the network medium linking devices.
FDDI-II (fiber data distributed interface II). Designed to accommodate the same speeds as FDDI-I, but over a twisted-pair copper cable.
Federal Communications Commission (FCC). The U.S. federal government organization responsible for the regulation of broadcasting, cable, telephony, satellites, and other communications media.
Fiber-in-the-loop (FITL). The deployment of fiber optic cable in the local loop, which is the area between the telephone company’s central office and the subscriber.
Fiber optics. Thin strands of ultrapure glass or plastic used to carry light waves from one location to another.
Fiber-to-the-cabinet (FTTCab). Network architecture where an optical fiber connects the telephone switch to a street-side cabinet. The signal is converted to feed the subscriber over a twisted copper pair.
Fiber-to-the-curb (FTTC). The deployment of fiber optic cable from a central office to a platform serving numerous homes. The home is linked to this platform with coaxial cable or twisted pair (copper wire). Each fiber carries signals for more than one residence, lowering the cost of installing the network versus fiber-to-the-home.
Fiber-to-the-home (FTTH). The deployment of fiber optic cable from a central office to an individual home. This is the most expensive broadband network design, with every home needing a separate fiber optic cable to link it with the central office.
Fiber-to-the-node (FTTN). The deployment of fiber optic cable from a central office to neighborhood, where one connection serves a number of houses.
Fixed satellite services (FSS). The use of geosynchronous satellites to relay information to and from two or more fixed points on the earth’s surface.
FM (frequency modulation). A method of superimposing a signal on a carrier wave in which the frequency on the carrier wave is continuously varied. FM radio and the audio portion of an NTSC television signal use frequency modulation.
Footprint. The coverage area of a satellite signal, which can be focused to cover specific geographical areas.
Frame. One complete still image that makes up a part of a video signal.
Frame relay. A high-speed packet switching protocol used in wide area networks (WANs), often to connect local area networks (LANs) to each other, with a maximum bandwidth of 44.725 Mb/s.
Frequency. The number of oscillations in an alternating current that occur within one second, measured in Hertz (Hz).
Frequency division multiplexing (FDM). The transmission of multiple signals simultaneously over a single transmission path by dividing the available bandwidth into multiple channels that each cover a different range of frequencies.
FTP (file transfer protocol). An Internet application that allows a user to download and upload programs, documents, and pictures to and from databases virtually anywhere on the Internet.
FTTC. See Fiber-to-the-curb.
FTTH. See Fiber-to-the-home.
FTTN. See Fiber-to-the-node.
Full-motion video. The projection of 20 or more frames (or still images) per second to give the eye the perception of movement. Broadcast video in the United States uses 30 frames per second, and most film technologies use 24 frames per second.
Fuzzy logic. A method of design that allows a device to undergo a gradual transition from on to off, instead of the traditional protocol of all-or-nothing.
G G.dmt. A kind of asymmetric DSL technology, based on DMT modulation, offering up to 8 Mb/s downstream bandwidth, 1.544 Mb/s upstream bandwidth. “G.dmt” is actually a nickname for the standard officially known as ITU-T Recommendation G.992.1. (See International Telecommunications Union.)
G.lite [pronounced “G-dot-light”]. A kind of asymmetric DSL technology, based on DMT modulation, that offers up to 1.5 Mb/s downstream bandwidth, 384 Kb/s upstream, does not usually require a splitter, and is easier to install than other types of DSL. “G.lite” is a nickname for the standard officially known as G.992.2. (See International Telecommunications Union.)
Geosynchronous orbit (GEO, also known as geostationary orbit). A satellite orbit directly above the equator at 22,300 miles. At that distance, a satellite orbits at a speed that matches the revolution of the earth so that, from the earth, the satellite appears to remain in a fixed position.
Gigabyte. 1,000,000,000 bytes or 1,000 megabytes (see Byte).
Global positioning system (GPS). Satellite-based services that allow a receiver to determine its location within a few meters anywhere on earth.
Gopher. An early Internet application that assisted users in finding information on and accessing the resources of remote computers.
Graphical user interface (GUI). A computer operating system that is based on icons and visual relationships rather than text. Windows and the Macintosh computer use GUIs because they are more user friendly.
Groupware. Computer software applications that facilitates intraorganizational communication, allowing multiple users to access and change files, send and receive e-mail, and keep track of progress on group projects.
GSM (Group standard mobile). A type of digital cellular telephony used in Europe that uses time-division multiplexing to carry multiple signals in a single frequency.
GUI. See Graphical user interface.
H Hardware. The physical equipment related to a technology.
HD-DVD. One of two competing high-definition DVD formats.
HD Radio. The marketing term used for digital radio broadcasting in the U.S. (See IBOC.)
HDSL. See High bit-rate digital subscriber line.
Hertz. See Frequency.
HFC (hybrid fiber/coax). A type of network that includes a fiber optic “backbone” to connect individual nodes and coaxial cable to distribute signals from an optical network interface to the individual users (up to 500 or more) within each node.
High bit-rate digital subscriber line (HDSL). A symmetric DSL technology that provides a maximum bandwidth of 1.5 Mb/s in each direction over two phone lines, or 2 Mb/s over three phone lines.
High bit-rate digital subscriber line II (HDSL II). A descendant of HDSL that offers the same performance over a single phone line.
High-definition television (HDTV). Any television system that provides a significant improvement in existing television systems. Most HDTV systems offer more than 1,000 scan lines, in a wider aspect ratio, with superior color and sound fidelity.
Hologram. A three-dimensional photographic image made by a reflected laser beam of light on a photographic film.
Home networking. Connecting different electronic devices in a household by way of a local area network (LAN).
Hotspot. An area in which wireless, public Internet access is available using one or more of the Wi-Fi protocols.
HTML. See Hypertext markup language.
http (hypertext transfer protocol). The first part of an address (URL) of a site on the Internet, signifying a document written in hypertext markup language (HTML).
Hybrid fiber/coax (HFC). A type of network that includes coaxial cables to distribute signals to a group of individual locations (typically 500 or more) and a fiber optic backbone to connect these groups.
Hypertext. Documents or other information with embedded links that enable a reader to access tangential information at programmed points in the text.
Hypertext markup language (HTML). The computer language used to create hypertext documents, allowing connections from one document or Internet page to numerous others.
Hz. An abbreviation for Hertz. See Frequency.
I IBOC (In-band, on-channel). The transmission system for digital broadcasting in the U.S. that incorporates a digital radio signal on the same transmission frequency used for analog broadcasting.
ILEC. See Incumbent local exchange carrier.
Image stabilizer. A feature in camcorders that lessens the shakiness of the picture either optically or digitally.
Incumbent local exchange carrier (ILEC). A large telephone company that has been providing local telephone service in the United States since the divestiture of the AT&T telephone monopoly in 1982.
Institute of Electrical & Electronics Engineers (IEEE). A membership organization comprised of engineers, scientists, and students that sets standards for computers and communications.
Instructional Television Fixed Service (ITFS). A microwave television service designed to provide closed-circuit educational programming. Underutilization of these frequencies led wireless cable (MMDS) operators to obtain FCC approval to lease these channels to deliver television programming to subscribers.
Interactive TV (ITV). A television system in which the user interacts with the program.
Interexchange carrier. Any company that provides interLATA (long distance) telephone service.
Interlaced scanning. The process of displaying an image using two scans of a screen, with the first providing all the even-numbered lines and the second providing the odd-numbered lines.
International Organization of Standardization (ISO). Develops, coordinates, and promulgates international standards that facilitate world trade.
Internet Engineering Task Force (IETF). The standards organization that standardizes most Internet communication protocols, including Internet protocol (IP) and hypertext transfer protocol (HTTP).
Internet service provider (ISP). An organization offering and providing Internet access to the public using computer servers connected directly to the Internet.
Intranet. A network serving a single organization or site that is modeled after the Internet, allowing users access to almost any information available on the network. Unlike the Internet, Intranets are typically limited to one organization or one site, with little or no access to outside users.
IP (Internet protocol). The standard for adding “address” information to data packets to facilitate the transmission of these packets over the Internet.
IPTV (Internet protocol television). The distribution of television programming over the Internet or other network through the use of Internet protocol packet switching.
ISDN (Integrated Services Digital Network). A planned hierarchy of digital switching and transmission systems synchronized to transmit all signals in digital form, offering increased capacity over analog networks.
ISO. See International Organization of Standardization.
ISP. See Internet service provider.
ITU (International Telecommunications Union). A U.N. organization that coordinates use of the spectrum and creation of technical standards for communication equipment.
J JPEG (Joint Photographic Experts Group). A committee formed by the ISO to create a digital compression standard for still images. Also refers to the digital compression standard for still images created by this group.
K Killer app. Short for “killer application,” this is a function of a new technology that is so strongly desired by users that it results in adoption of the technology.
Kilobit. One thousand bits (see Bit).
Kilobyte. 1,000 bytes (see Byte).
Ku-band. A set of microwave frequencies (12 GHz to 14 GHz) used exclusively for satellite communication. Compared to C-band, the higher frequencies produce shorter waves and require smaller receiving dishes.
L LAN. See Local area network.
Laser. From the acronym for “light amplification by stimulated emission of radiation.” A laser usually consists of a light-amplifying medium placed between two mirrors. Light not perfectly aligned with the mirrors escapes out the sides, but light perfectly aligned will be amplified. One mirror is made partially transparent. The result is an amplified beam of light that emerges through the partially transparent mirror.
Last mile. See Local loop.
LATA (local access transport area). The geographical areas defining local telephone service. Any call within a LATA is handled by the local telephone company, but calls between LATAs must be handled by long distance companies, even if the same local telephone company provides service in both LATAs.
LEO (low earth orbit). A satellite orbit between 400 and 800 miles above the earth’s surface. The close proximity of the satellite reduces the power needed to reach the satellite, but the fact that these satellites complete an entire orbit in a few hours means that a large number of satellites must be used in a LEO satellite system in order to have one overhead at all times.
Liner notes. The printed material that accompanies a CD or record album, including authors, identification of musicians, lyrics, pictures, and commentary.
LMDS (local multipoint distribution service). A new form of wireless technology similar to MMDS that uses frequencies above 28 GHz.
Local area network (LAN). A network connecting a number of computers to each other or to a central server so that computers can share programs and files.
Local exchange carrier (LEC). A local telephone company.
Local loop. The copper lines between a customer’s premises and a telephone company’s central office (see Central office).
M Mb/s. Megabits per second.
M-commerce. Mobile commerce—the use of cellular telephones and other wireless mobile devices to buy and sell goods and services.
Megabit. One million bits.
Megabyte. 1,000,000 bytes or 1,000 kilobytes (see Byte).
Megapixel. Refers to one million pixels, and is used as a measure of the quality of digital cameras. The more pixels used for a picture, the higher the quality.
Microcell. The area, typically a few hundred yards across, served by a single transmitter in a PCS network. The use of microcells allows the reuse of the same frequencies many times in an area, allowing more simultaneous users.
MIDI (musical instrument digital interface). An international standard for representing music in digital form. Music can be directly input from a computer keypad and stored to disc or RAM, then played back through a connected instrument. Conversely, a song can be played by the performer on an instrument interfaced with the computer.
MIPS (millions of instructions per second). This is a common measure of the speed of a computer processor.
MMDS (multichannel multipoint distribution systems). A service similar to cable television that uses microwaves to distribute the signals instead of coaxial cable. MMDS is therefore better suited to sparsely-populated areas than cable.
Mobile satellite services (MSS). The use of satellites to provide navigation services and to connect vehicles and remote regions with other mobile or stationary units.
Modem (MOdulator/DEModulator). Enables transmission of a digital signal, such as that generated by a computer, over an analog network, such as the telephone network.
Monochromatic. Light or other radiation with one single frequency or wavelength. Since no light is perfectly monochromatic, the term is used loosely to describe any light of a single color over a very narrow band of wavelengths.
MPEG (Moving Picture Experts Group). A committee formed by the ISO to set standards for digital compression of full-motion video. Also stands for the digital compression standard created by the committee that produces VHS-quality video.
MPEG-1. An international standard for the digital compression of VHS-quality, full-motion video.
MPEG-2. An international standard for the digital compression of broadcast-quality, full-motion video.
MTSO (mobile telephone switching office). The “heart” of a cellular telephone network, containing switching equipment and computers to manage the use of cellular frequencies and connect cellular telephone users to the landline network.
Multicast. The transmission of information over the Internet to two or more users at the same time.
Multimedia. The combination of video, audio, and text in a single platform or presentation.
Multiple system operator (MSO). A cable company that owns and operates many local cable systems.
Multiplexing. Transmitting several messages or signals simultaneously over the same circuit or frequency.
Must-carry. A set of rules requiring cable operators to carry all local broadcast television stations.
MVPD (Multichannel video programming distributor). A generic term used to refer to services such as cable television, DBS, etc. that offer a full range of television programming services.
N Nanometer. One billionth of a meter. Did you know that “nano” comes from the Greek word “dwarf?”
Narrowband. A designation of bandwidth less than 56 Kb/s.
National information infrastructure (NII). An initiative to support the private sector construction and maintenance of a “seamless web” of communication networks, computers, databases, and consumer electronics that will put vast amounts of information at users’ fingertips.
Near video on demand (NVOD). A pay-per-view service offering movies on up to eight channels, each with staggered start times so that a viewer can watch one at any time. NVOD is much more flexible than PPV, and costs far less than VOD to implement.
Network access provider (NAP). Another name for a provider of networked telephone and associated services, usually in the United States.
Network service provider (NSP). A high-level Internet provider that offers high-speed backbone services.
Newbies. New users of an interactive technology, usually identified because they have not yet learned the etiquette of communication in a system.
Nodes. Routers or switches on a broadband network that provide a link from point A to point B across a network.
NTSC (National Television Standards Committee). The group responsible for setting the U.S. standards for color television in the 1950s.
O OCR (optical character recognition). Refers to computer programs that can convert images of text to text that can be edited.
Octet. A byte, more specifically, an eight-bit byte. The origins of the octet trace back to when different networks had different byte sizes. Octet was coined to identify the eight-bit byte size.
Operating system. The program embedded in most computers that controls the manner in which data are read, processed, and stored.
Optical carrier 3 (OC3). A fiber optic line carrying 155 Mb/s, a U.S. designation generally recognized throughout the telecommunications community worldwide.
Optical network unit (ONU). A form of access node that converts optical signals transmitted via fiber to electrical signals that can be transmitted via coaxial cable or twisted pair copper wiring to individual subscribers. See Hybrid fiber/coax.
Overlay. The process of combining a graphic with an existing video image.
P Packet switched networks. A network that allows a message to be broken into small “packets” of data that are sent separately by a source to the destination. The packets may travel different paths and arrive at different times, with the destination site reassembling them into the original message. Packet switching is used in most computer networks because it allows a very large amount of information to be transmitted through a limited bandwidth.
Passive optical network (PON). A fiber-based transmission network with no active electronics.
PCN (personal communications network). Similar to PCS, but incorporating a wider variety of applications including voice, data, and facsimile.
PCS (personal communications services). A new category of digital cellular telephone service which uses much smaller service areas (microcells) than ordinary cellular telephony.
Peripheral. An external device that increases the capabilities of a communications system.
Personal digital assistants (PDAs). Extremely small computers (usually about half the size of a notebook) designed to facilitate communication and organization. A typical PDA accepts input from a special pen instead of a keyboard, and includes appointment and memo applications. Some PDAs also include fax software and a cellular telephone modem to allow faxing of messages almost anywhere.
Photovoltaic cells. A device that converts light energy to electricity.
Pixel. The smallest element of a computer display. The more pixels in a display, the greater the resolution.
Point of presence (POP). The physical point of connection between a data network and a telephone network.
Point-to-multipoint service. A communication technology designed for broadcast communication, where one sender simultaneously sends a message to an unlimited number of receivers.
Point-to-point service. A communication technology designed for closed-circuit communication between two points such as in a telephone circuit.
POTS (plain old telephone service). An acronym identifying the traditional function of a telephone network to allow voice communication between two people across a distance.
POTS splitter. A device that uses filters to separate voice from data signals when they are to be carried on the same phone line. Required for several types of DSL service.
PPV (pay-per-view). A television service in which the subscriber is billed for individual programs or events.
Progressive scanning. A video display system that sequentially scans all the lines in a video display.
PTT. A government organization that offers telecommunications services within a country. (The initials refer to the antecedents of modern communication: the post [mail], telephone, and telegraph.)
Q QuickTime. A computer video playback system that enables a computer to automatically adjust video frame rates and image resolution so that sound and motion are synchronized during playback.
R RBOC (regional Bell operating company). One of the seven local telephone companies formed upon the divestiture of AT&T in 1984. The original seven were Bell Atlantic, NYNEX, Pacific Telesis, BellSouth, Southwestern Bell, U S WEST, and Ameritech.
Retransmission consent. The right of a television station to prohibit retransmission of its signal by a cable company. Under the 1992 Cable Act, U.S. television stations may choose between must-carry and retransmission consent.
RF (radio frequency). Electromagnetic carrier waves upon which audio, video, or data signals can be superimposed for transmission.
Roaming. Movement of a wireless node between two microcells.
Router. The central switching device that directs and controls the flow of data through the computer network.
RSS (real simple syndication). An Internet application that tells a Web site or a special computer program that new information is available to download, “pushing” information to the user, rather than waiting for the user to request it.
S SCMS (Serial Copy Management System). A method of protecting media content from piracy that allows copies to be made of a specific piece of content, but will not allow copies of copies.
SCSI (small computer system interface) [pronounced “scuzzy”]. An outmoded type of interface between computers and peripherals.
SDTV (standard-definition television). Digital television transmissions that deliver approximately the same resolution and aspect ratio of traditional television broadcasts, but do so in a fraction of the bandwidth through the use of digital video compression.
SMPTE (Society of Motion Picture and Television Engineers). The industry group responsible for setting technical standards in most areas of film and television production.
Social Networking. The use of the Internet and other electronic media to allow individuals to create groups and communities for the sharing of information, entertainment, and activities.
Software. The messages transmitted or processed through a communications medium. This term also refers to the instructions (programs) written for programmable computers.
SONET (Synchronous Optical Network). A standard for data transfer over fiber optic networks used in the United States that can be used with a wide range of packet- and circuit-switched technologies.
Spot beam. A satellite signal targeted at a small area, or footprint. By concentrating the signal in a smaller area, the signal strength increases in the reception area.
SVOD (subscription video on demand). A pay television service that offers a range of VOD (video on demand) programming for a monthly fee.
Symmetric digital subscriber line (SDSL). A DSL technology that provides a maximum bandwidth of 1.5 Mb/s using one phone line, with a downstream transmission rate that equals the upstream transmission rate and allows use of POTS service on the same phone line. SDSL also refers to single-line digital subscriber line.
Synchronous transmission. The transmission of data at a fixed rate, based on a master clock, between the transmitter and receiver.
T T-commerce. Television commerce—the use of interactive television to buy and sell goods and services.
T1. A standard for physical wire cabling used in networks. A T-1 line has the bandwidth of 1.54 Mb/s.
T3. A standard for physical wire cabling that has the bandwidth of 44.75 Mb/s.
TCP/IP (transmission control protocol/Internet protocol). A method of packet-switched data transmission used on the Internet. The protocol specifies the manner in which a signal is divided into parts, as well as the manner in which “address” information is added to each packet to ensure that it reaches its destination and can be reassembled into the original message.
TDMA (time division multiple access). A cellular telephone technology that sends several digital signals over a single channel by assigning each signal a periodic slice of time on the channel. Different TDMA technologies include North America’s Interim Standard (IS) 54, Europe’s global system for mobile communications, and a version developed by InterDigital Corporation. These systems differ in circuits per channel, timing, and channel width.
Telecommuting. The practice of using telecommunications technologies to facilitate work at a site away from the traditional office location and environment.
Teleconference. Interactive, electronic communication among three or more people at two or more sites. Includes audio-only, audio and graphics, and videoconferencing.
Teleport. A site containing multiple satellite uplinks and downlinks, along with microwave, fiber optic, and other technologies to facilitate the distribution of satellite signals.
Terabyte. 1,000,000,000,000 bytes or 1,000 gigabytes (see Byte).
Time division multiplexing (TDM). The method of multiplexing where each device on the network is provided with a set amount of link time.
Transponder. The part of a satellite that receives an incoming signal from an uplink and retransmits it on a different frequency to a downlink.
TVRO (television receive only). A satellite dish used to receive television signals from a satellite.
Twisted pair. The set of two copper wires used to connect a telephone customer with a switching office. The bandwidth of twisted pair is extremely small compared with coaxial cable or fiber optics.
U UGC (User generated content). Media content that is created by consumers for distribution to other consumers, either directly or through media channels.
UHF (ultra high frequency). Television channels numbered 14 through 83.
Ultra-high definition television. An experimental television format developed by NHK offering approximately 16 times the detail found in high-definition television. The format has 4320 scan lines, with a resolution of 7680 pixels per line.
Universal ADSL Working Group (UAWG). An organization composed of leading personal computer industry, networking, and telecommunications companies with the goal of creating an interoperable, consumer-friendly ADSL standard entitled the G.992.2 standard, and commonly referred to as the G.lite standard.
Universal serial bus (USB). A computer interface with a maximum bandwidth of 1.5 Mb/s used for connecting computer peripherals such as printers, keyboards, and scanners.
Universal service provider (USP). A company that sells access to phone, data, and entertainment services and networks.
Universal service. In telecommunications policy, the principle that an interactive telecommunications service must be available to everyone within a community in order to increase the utility and value of the network for all users.
Uplink. An antenna that transmits a signal to a satellite for relay back to earth.
URL (uniform resource locator). An “address” for a specific page on the Internet. Every page has a URL that specifies its server and file name.
V Variable bit rate (VBR). Data transmission that can be represented by an irregular grouping of bits or cell payloads followed by unused bits or cell payloads. Most applications other than voice circuits generate VBR traffic patterns.
VDSL (Very high bit-rate digital subscriber line). An asymmetric DSL that delivers from 13 Mb/s to 52 Mb/s downstream bandwidth and 1.5 Mb/s to 2.3 Mb/s upstream.
Vertical blanking interval (VBI). In an NTSC television signal, the portion of the signal that is not displayed on a television receiver. Some of the lines in the VBI contain “sync” information that is used to identify the beginning of a new picture. Some of the blank lines in the VBI can be used to carry data such as closed captions.
Vertical integration. The ownership of more than one function of production or distribution by a single company, so that the company, in effect, becomes its own customer.
VHF (very high frequency). Television channels numbered 2 through 13.
Videoconference. Interactive audio/visual communication among three or more people at two or more sites.
Video on demand (VOD). A pay-per-view television service in which a viewer can order a program from a menu and have it delivered instantly to the television, typically with the ability to pause, rewind, etc.
Videophone. A telephone that provides both sound (audio) and picture (video).
Videotext (also known as videotex). An interactive computer system using text and/or graphics that allows access to a central computer using a terminal or personal computer to engage in data retrieval, communication, transactions, and/or games.
Virtual reality (VR). A cluster of interactive technologies that gives users a compelling sense of being inside a circumambient environment created by a computer.
Vlog. A video blog.
VoIP (Voice over Internet Protocol). A set of standards designed to enable telephone communications over data networks using packet-based switching (as opposed to circuit-based switching used in traditional telephone networks.
VRML (virtual reality markup language). A computer language that provides a three-dimensional environment for traditional Internet browsers, resulting in a simple form of virtual reality available over the Internet.
VSAT (very small aperture terminal). A satellite system that uses relatively small satellite dishes to send and receive one- or two-way data, voice, or even video signals.
W Web Services. The name given to the set of protocols including XML, SOAP, and J2EE that facilitate sharing of information across programs and platforms, allowing interconnection of disparate databases.
Wide area network (WAN). A network that interconnects geographically distributed computers or LANs.
Wi-Fi. A collective term for a set of wireless data standards offering speeds up to 54 Mb/s, including 802.11a, 802.11b, and 802.11g.
Wiki. Internet content or Web sites that consist of content is created and edited by the users of the content.
Wi-MAX. Another name for the IEEE standard 802.16, which consists of a set of standards for fixed and mobile wireless data communication offering speeds of up to 120 Mb/s in the 10-66 GHz frequency range.
Wireless cable. See MMDS.
Wireless node. A user computer with a wireless network interface card.
WORM (write once, read many). A technique that allows recording of information on a medium only once, with unlimited playback.
X X.25 data protocol. A packet switching standard developed in the mid-1970s for transmission of data over twisted-pair copper wire.
xDSL. See Digital subscriber line.
XML. (Extensible markup language). A protocol used to code information in a computer program so that information can be shared across numerous programs and platforms.
