hybrid fiber coaxial cable (HFC)A telecommunications cable in which optical fiber cable and coaxial cable constitute different portions of a network carrying broadband content (such as…
hybrid interface structureIn integrated services digital networks (ISDN), an interface structure that uses both labeled and positioned channels.
hybrid junctionA waveguide or transmission line arranged such that (a) there are four ports, (b) each port is terminated in its characteristic impedance, and (c) energy…
hybrid modeA mode consisting of components of both electrical and magnetic field vectors in the direction of propagation.
hybrid routingRouting in which numbering plans and routing tables are used to permit the collocation, in the same area code, of switches using a deterministic routing…
hybrid setTwo or more transformers interconnected to form a network having four ports that are conjugate in pairs.
hybrid spread spectrumA combination of frequency hopping spread spectrum and direct-sequence spread spectrum. [NTIA]
hybrid systemA renewable energy system that includes two different types of technologies that produce the same type of energy; for e.g.
hydroxyl ion absorptionIn optical fibers, the absorption of electromagnetic waves, including the near-infrared, due to the presence of trapped hydroxyl ions remaining from water…
hyperlinkA link - usually appearing as a highlighted word or picture within a hypertext document - that when clicked changes the active view, possibly to another…
hypermediaComputer-addressable files that contain pointers for linking to multimedia information, such as text, graphics, video, or audio in the same or other…
HyperTextText that includes links or shortcuts to other documents or views, allowing the reader to easily jump from one view to a related view in a non-linear…
IANAAbbreviation for Internet Assigned Numbers Authority. An organization directed by the Internet Architecture Board (IAB) and which assigns IP numbers and…
IBInternational Bureau - the secretariat of the WIPO which, among other functions, centralizes information of various kinds relating to the protection of…
ICInternational Class - class(es) assigned to a mark under the International Classification of Goods and Services (Nice Agreement); used in the United…
IDEA (International Data Encryption Algorithm)Developed in Switzerland and licensed for non-commercial use in PGP. IDEA uses a 128 bit user supplied key to perform a series of nonlinear mathematical…
IdentificationThe process of verifying the identity of a user, process, or device, usually as a prerequisite for granting access to resources in an IT system.
Identification Friend or Foe (IFF)A system using electromagnetic transmissions to which equipment carried by friendly forces automatically responds, fro example by emitting pulses, thereby…
identification friend or foe personal identifierThe discrete identification, friend or foe code assigned to a particular aircraft, ship, or other vehicle for identification by electronic means. [JP1]
identification informationA form of notification information that consists of the documentation of the actual sequence of intermediate networks traversed by a signaling message.
identifier (ID)In telecommunications and data processing systems, one or more characters used to identify, name, or characterize the nature, properties, or contents of a…
IdentityThe topological overlay of a coverage (input) with a polygon coverage (identity).
identity authenticationThe performance of tests to enable a data processing system to recognize entities.
identity tokenA device, such as a metal key or smart card, used for identity authentication. [After 2382-pt.8] 2.
identity validationTests enabling an information system to authenticate users or resources. [INFOSEC-99]
Identity-Based Security PolicyA security policy based on the identities and/or attributes of the object (system resource) being accessed and of the subject (user, group of users…
IDFInverse Document Frequency is a term used to help determine the position of a term in a vector space model.
idle characterA control character that is transmitted when no useful information is being transmitted. [From Weik '89]
idle codeA special sequence that indicates that no data are being sent on the channelized side. [T1.509-1995]
idle stateThe telecommunications service condition that exists whenever user messages are not being transmitted but the service is immediately available for use.
idle timeA period during which a system, circuit, or component is not in use, but is available.
idle-channel noiseNoise that is present in a communications channel when no signals are applied. Note: The channel conditions and terminations must be stated for…
idle-line terminationA switch-controlled electrical network that maintains a desired impedance at a trunk or line terminal that is in the idle state.
IF1 (interface 1)An interface suitable for star concentration. [T1.201-1987] [T1.204-1988]
IF2 (interface 2)An interface suitable for communication between a network element (NE) location and operations systems (OSs) over packet switched networks, dedicated…
IF4 (interface 4)An interface suitable for multipoint concentration by polling. [T1.201-1987] [T1.204-1988]
IF6 (interface 6)An interface between a network element (NE) to one or more network elements (NEs) in other locations using star configuration embedded operations channel…
ILECAbbreviation for incumbent local exchange carrier. The incumbent or existing franchised local exchange carrier in any given area. [After FCC]
illegal characterA character, or a combination of bits, that is not valid in a given system according to specified criteria, such as with respect to a specified alphabet…
IMWithin or into muscle. Also called intramuscular.
ImageTo image a hard drive is to make an identical copy of the hard drive, including empty sectors.
image antennaA hypothetical mirror-image, i.e., virtual-image, of an antenna, i.e., antenna element, considered to extend as far below ground, i.e.
image captureThe transducing of the information in a real image into the photographic or electronic medium.
image compressionApplication of an appropriate transfer function to an image signal so as to limit dynamic range. 2.
image enhancementIn video technology, a technique used to improve contrast and picture clarity by flattening the camera response to 400 lines (by aperture correction) and…
image file architectureThe formalization of a multidisciplinary agreement-regarding digital image characteristics, such as the structure of digital image files, the organization…
image file descriptorA block of data that (a) may contain, in standardized format, data concerning production, ownership, access, previous processing, etc.
image file headerA compact label for image files, created using a universally accepted algorithm, that (a) identifies the encoding standard, (b) specifies the length of…
image file motion-picture formatThe defining file format for exchange of digital motion-picture information on a variety of media between computer-based systems.
image file video indexA recommended practice intended to provide a method of coding video index information in which various picture- and program-related source data can be…
image frequencyIn radio reception using heterodyning in the tuning process, an undesired input frequency that is capable of producing the same intermediate frequency…
image generationThe creation of an image from an image concept. Note: The image can be created with computer-graphics software or photography, for example.
image mapAn image divided into logical areas, each of which has a hot spot.
image rejection ratioIn reception using heterodyning in the tuning process, the ratio of (a) the intermediate-frequency (IF) signal level produced by the desired input…
imagery(IH-mij-ree) A technique in which the person focuses on positive images in his or her mind.
immediate activationIn cryptology, a condition of readiness associated with a key having no effective date.
immediate messageA category of precedence reserved for messages relating to situations that gravely affect the security of national/allied forces or populace and that…
Immunity(ih-MYOO-nih-tee) The condition of being protected against an infectious disease.
ImpairedIs where an individual circuit exceeds the transmission limits or where the quality of service is diminished.
impedanceThe amount of resistance (or cost) required to traverse a line from its origin node to its destination node or to make a turn (i.e.
impedance matchingThe connection of an additional impedance to an existing one in order to accomplish a specific effect, such as to balance a circuit or to reduce…
implantA substance or object that is put in the body as a prosthesis, or for treatment or diagnosis.
ImplementationHow a piece of code actually goes about doing its job. Users of the code should not count on implementation details staying the same unless they are part…
implicit congestion controlA scheme under which user terminals first detect a possible congestion condition by means other than explicit congestion messages, and then take…
implicit servicesServices that a platform provides without a direct request [POSIX.0].
improved-definition television (IDTV)Television transmitters and receivers that (a) are built to satisfy performance requirements over and above those required by the NTSC standard and (b)…
Impulse(abbrev. IMPL) Alternate term for Upper Level System and Shortwave; a general term for any large-scale or mesoscale disturbance capable of producing…
impulse excitationThe production of oscillation in a circuit or device by impressing a stimulus (signal) for a period that is extremely short compared to the duration of…