A measure of the information-carrying capacity of a communications channel. The speed (bit rate or velocity) at which data can be transferred and presented.
Any system able to deliver multiple channels and/or services to its users or subscribers. Generally refers to cable-television systems. Sometimes called wideband.
Term characterizing both digital and analog transmission systems. Broadband communications is generally understood to indicate either a fast data-rate digital system or a wide bandwidth analog system.
Cable Television System (CATV)
A broadband communications system capable of delivering multiple channels of programming from a set of centralized satellite and off-air antennae, generally by coaxial cable, to a community. Many cable-television designs integrate fiber-optic and microwave links.
A telecommunications company that offers communications services to the general public via shared circuits at published tariff rates. In the United States, the Federal Communications Commission or various state public-utility commissions regulate common carriers.
An acronym for "compact disk-read only memory." An optical-storage device, identical to those used to record music, that holds roughly 600 times as much data--including text, graphics, sound, and video--as a standard computer floppy disk.
A type of cable used for broadband data and cable systems. Also known as "coax."
A function that operates in discrete steps as contrasted with a continuous, or analog, function. Digital computers manipulate numbers encoded in binary (on-off) forms, while analog computers sum continuously varying forms. Digital communications is the transmission of information using discontinuous, discrete electrical or electromagnetic signals that change in frequency, polarity, or amplitude. Analog forms may be encoded for transmission on digital communications systems.
Providing scholastic instruction to one or more remote locations from an originating classroom. This may be either one-way video with two-way audio or two-way video and audio. The transmission may be via satellite, cable TV, or switched networks.
Electronic mail (E-mail)
The delivery of correspondence, including graphics, by electronic means, usually by interconnecting computers, word processors, or facsimile equipment.
A form of LAN data link that uses IEEE 802.3/ISO 8802-3 carrier-sense multiple access with collision detection (CSMA/CD) standards. Ethernet LANs are typically wired in a star with a central wiring hub and stations are attached to a common transmission facility, such as twisted-pair cable or coaxial cable. 10 BaseT Ethernet has a transmission speed of 10 Mbps.
Term used to describe the standards used to define 100 Mbps version of the CMSA/CD (Ethernet) standard.
Fiber Distributed Data Interface (FDDI)
A networking technology that uses a dual ring topology often with dual networking equipment (concentrators, etc.). FDDI facilitates redundancy and protection of the network. If a device fails, the primary and secondary rings enter a "wrap" state to form a logical connection and thus maintain the logical ring in the event of a link failure. FDDI is capable of data rates of 100 Mbps over fiber optic cable (SMF and MMF). FDDI LAN standards were developed by subcommittee X3T9.5 of ANSI.
A cable containing one or more optical fibers.
The technology of guiding and projecting light for use as a communications medium. Hair- thin glass fibers that allow light beams to be bent and reflected with low levels of loss and interference are known as "glass optical wave guides" or simply "optical fibers."
The electrical and mechanical equipment used in telecommunications and computer systems. Contrasted with software, hardware is the programs and files that are in the equipment.
The control center of a cable-television system, where incoming signals are amplified, converted, processed, and combined into a common cable for transmission to subscribers.
A nonlinear way of presenting information that allows users to access related works or images from a single computer screen. For example, a user reading an encyclopedia entry on jazz could also hear excerpts from recordings, read biographies of jazz artists, and view photos of them. Apple Computer Inc.'s Hypercard is the best-known example of hypermedia. Presumably, this type of interface is similar to normal human cognitive processes. Also known as "hypertext."
Integrated Services Digital Network (ISDN)
A public-switched network providing digital connections for the concurrent transmission of voice, video, data, and images. Often seen as a technological bridge between the current telephone system and an upgraded, broadband network.
New telecommunications systems designed to permit two-way communications between televisions or computers in one location with software stored on a central computer. Can also allow individuals in distant locations to communicate, teach, or learn from one another.
Interactive Television (ITV)
Two-way communications using a television as a display. Uses include entertainment, information retrieval, education, and shopping.
A widely used public computer network, initially developed by the U.S. military, that links smaller computer networks and allows users on different electronic-mail systems to communicate with one another on a global scale.
Internet Protocol (IP)
In TCP/IP, a connection Internet layer protocol that provides a best-efforts datagram delivery service. Note the functional layer (TCP/IP) corresponds to the OSI model network layer. The Internet layer provides routing and relaying functions that are used when data must be passed from a host to some other network in the Internet. It operates in the source and destination hosts and in all the routers along the path between the hosts.
Local Area Network (LAN)
A special linkage of computers or other communications devices into their own network for use by an individual or organization, such as a schoolwide network.
National Information Infrastructure (NII)
A broad proposal for the federal government to establish standards and governing bodies for the transmission of digital data. Most provisions of the NII are still being debated.
National Telecommunications and Information Administration (NTIA)
An office of the U.S. Commerce Department that is designated to provide "seed grants" to support experimental education and other public-benefit uses of the NII.
The circuits over which computers or other devices are connected with one another, such as over a telephone network.
Being actively connected to a network or computer system; usually being able interactively to exchange data, commands, and information.
An industrywide standard that allows different telecommunications vendors to interconnect with a network. The industry standard is the OSI Model, a seven-layer reference model for Open Systems Interconnection, developed by the members of the International Organization for Standardization (ISO).
Public Utilities Commission
The body, usually a state entity, that sets telephone rates.
Synchronous Optical Network (SONET)
Physical layer communication facilities, using fiber optics, on which broadband ISDN services are based. OC-1 SONET provides 51 Mbps, OC-3 SONET provides a 155 Mbps data rate, OC-12 SONET provides a 622 Mbps data rate, and OC-48 SONET provides a 2.4 Gbps data rate.
Telecommunications line with bandwidth capacity of 1.54 Mbps.
Telecommunications line with bandwidth capacity of 45 Mbps.
The simultaneous visual and/or sound interconnection that allows individuals in two or more locations to see and talk to one another in a long-distance conference arrangement.
Shorthand notation for an IEEE/ISO CSMA/CD (Ethernet) LAN medium specification in which the data rate is 10 Mbps, the transmission technique is baseband, and the maximum cable segment length is 100 meters. 10 BASET-T is the CSMA/CD medium specification that specifies the use of twisted-pair cable.
Transmission Control Protocol/Internet Protocol (TCP/IP)
A set of communications protocols that grew out of a research project that was funded by the U.S. Department of Defense. The TCP/IP networking scheme implements a peer-to- peer client-server architecture. Any computing system in the network can run TCP/IP server software and can provide services to any other computing system that runs complementary TCP/IP client software.
Traditionally defined as making affordable voice telephone service easily available. In the coming years, it could be broadened to include other telecommunications services.
Wide-Area Network (WAN)
A network of computers spread out over a large geographical area (compare with local area network). Florida, Kentucky, Pennsylvania, Texas, and Virginia have developed, or are developing, statewide computer networks dedicated to education use.
World Wide Web (WWW)
An Internet service that lets users retrieve hypertext and graphics from various sites. Often just called "the Web," it has become one of the most popular Internet services over the past two years.
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