Telecommunications terms starting with F

396 terms

F layer See F region.
F Region In solar-terrestrial terms, the upper layer of the ionosphere, approximately 120 to 1500 km in altitude.
facet erosion In laser diodes, a phenomenon in which a high field intensity of stimulated optical radiation causes degradation of the facets, i.e.
facility A fixed, mobile, or transportable structure, including (a) all installed electrical and electronic wiring, cabling, and equipment and (b) all supporting…
facility assembly A group of interconnected equipment and transmission media uniquely identified and dedicated to a specific type of service. [T1.238-1994/97]
facility code A two-digit code (FC) used in the exchange-carrier-to-interexchange carrier (EC-to-IC) facility/service selective signaling protocol and the IC-to-EC…
facility grounding system The electrically interconnected system of conductors and conductive elements that (a) provides multiple current paths to the earth electrode subsystem…
facility group The particular group of facilities to route the call. [T1.667-1999]
facility group member The specific member of a trunk group or a multi-line hunt group. [T1.667]
facsimile (FAX) A form of telegraphy for the transmission of fixed images, with or without half-tones, with a view to their reproduction in a permanent form.
facsimile converter In a facsimile receiver, a device that changes the signal modulation from frequency-shift keying (FSK) to amplitude modulation (AM). 2.
facsimile frequency shift At any point in a frequency-shift facsimile system, the numerical difference between the frequency that corresponds to a white signal and the frequency…
facsimile picture signal In facsimile systems, the baseband signal that results from the scanning process.
facsimile receiver In a facsimile system, the equipment that converts the facsimile picture signal into a recorded copy.
facsimile recorder In a facsimile receiver, the device that performs the final conversion of the facsimile picture signal to an image of the object, i.e.
facsimile signal level In a facsimile system, the signal level at any point in the system. Note 1: The facsimile signal level is used to establish the operating levels.
facsimile transceiver In a facsimile system, the equipment that sends and receives facsimile signals.
facsimile transmitter In a facsimile system, the equipment that converts the baseband picture signals, i.e.
Fade this means to cover all or part of the bank bet, also called cover or cover the bank.
fade margin A design allowance that provides for sufficient system gain or sensitivity to accommodate expected fading, for the purpose of ensuring that the required…
fading In a received signal, the variation (with time) of the amplitude or relative phase, or both, of one or more of the frequency components of the signal.
fading distribution The probability distribution that signal fading will exceed a given value relative to a specified reference level.
fading margin Synonym fade margin.
fail See failure, graceful degradation.
fail safe Of a device, the capability to fail without detriment to other devices or danger to personnel. 2.
fail soft [The] selective termination of affected nonessential processing, when hardware or software failure is determined to be imminent. [INFOSEC-99]
fail-safe operation Operation that ensures that a failure of equipment, process, or system does not propagate beyond the immediate environs of the failing entity. 2.
Failure An incident resulting in the uncontrolled release of water from a dam. Destroyed and made useless, ceases to function as a dam.
failure access [An] Unauthorized access to data resulting from a hardware or software failure. [INFOSEC-99]
failure control [The methods] used to detect imminent hardware or software failure and provide fail safe or fail soft recovery. [INFOSEC-99]
fair queuing The controlling of congestion in gateways by restricting every host to an equal share of gateway bandwidth.
fake sector In information assurance, a sector consisting of a header but no data, used in large numbers on a diskette to cause an unauthorized copying program to…
fall time The time required for the amplitude of a pulse to decrease (fall) from a specified value (usually 90 percent of the peak value exclusive of overshoot or…
false character See illegal character.
false clock A condition where a phase-locked loop controlling a clock locks on a frequency other than the correct frequency.
false lock A condition where a phase-locked loop locks to a frequency other than the correct one, or to an improper phase.
fan out The process of splitting a message to deliver e-mail messages to individual recipients. [Exchange 2007]
fan-beam antenna A directional antenna producing a main beam having a large ratio of major to minor dimension at any transverse cross section.
fanout cable Synonym breakout cable.
FAQ file Abbreviation for Frequently Asked Questions file. An online file that contains frequently asked questions with answers provided to assist new users and…
Far Field The region far from an antenna compared to the dimensions of the antenna and the wavelength of the radiation.
far zone Synonym far-field region.
far-end block error (FEBE) An indication returned to a transmitting node (source) that an errored block has been detected at the receiving node (sink). [T1.105-1988]
far-end crosstalk Crosstalk that is propagated in a disturbed channel in the same direction as the propagation of a signal in the disturbing channel.
far-end customer interface An associated, loop signaling, customer installation located at the far end of the network transmission path from the network interface (NI) described in…
far-end receive failure (FERF) An indication returned to a transmitting link terminating equipment (LTE) upon receipt of a line AIS (alarm indication signal) code or detection of an…
far-field diffraction pattern The diffraction pattern of a source (such as an LED, ILD, or the output end of an optical fiber) observed at an infinite distance from the source.
far-field radiation pattern A radiation pattern measured at the far field of an antenna or other emitter.
far-field region The region where the angular field distribution is essentially independent of distance from the source.
Faraday effect A magneto-optic effect in which the polarization plane of an electromagnetic wave is rotated under the influence of a magnetic field parallel to the…
fast packet switching A packet switching technique that increases the throughput by eliminating overhead.
fast select An optional user facility in the virtual call service of CCITT X.25 protocol (now, ITU-T X.
fat client A client-centric computing model where software must be installed on each client in a network.
Fault "Fault" means adultery, alcohol abuse, drug abuse, physical abuse, domestic violence, abandonment or reckless spending.
fault management In network management, the set of functions that (a) detect, isolate, and correct malfunctions in a telecommunications network, (b) compensate for…
fault protection subsystem In a facility power distribution system, the subsystem that provides a direct path from each power sink to the earth electrode subsystem.
Fault-Tolerance The ability of a processor to maintain mission effectiveness after some subsystems failed.
FAX Short for facsimile. A process of transmitting documents by scanning them to digital, converting to analog, transmitting over phone lines and reversing…
FC A product of hydrolysis of an IgG antibody, consisting of parts of the constant regions of two heavy chains held together by a disulphide bridge, but…
FCC Federal Communications Commission.
FCC registration program The Federal Communications Commission program and associated directives intended to assure that all connected terminal equipment and protective circuitry…
FCS Fire Control Section.
FDDI Fiber Distributed Data Interface. An ANSI standard LAN architecture that uses optical fiber cable for high-speed transmission.
FDDI-2 See fiber distributed data interface.
FDHM See full width at half maximum.
FDM Common abbreviation for Financial Disclosure Management, the online program to electronically file and manage financial disclosure reports.
FDMA Abbreviation for frequency-division multiple access.
FDX Full Duplex (Telecomm/Computer term).
feature code A code (or codes) used to select/activate a service feature (e.g., forwarding, using two- or three-digit codes preceded by * or 1 1 or #, and which may…
FEC Abbreviation for forward error correction.
Federal Communications Commission See FCC.
Federal Networking Council (FNC) The body responsible for coordinating networking needs among U.S. Federal agencies.
Federal Telecommunications System (FTS) A switched long-distance telecommunications service formerly provided for official Federal Government use.
Federal Telecommunications System 2000 service See FTS2000.
Feed A component that "feeds" the signal from the optical system to the amplification electronics. Also called a "feed horn" or "horn".
feed-forward path In the encoder, the signal path from the input of the PCM-to-uniform-PCM converter to the output of the adaptive quantizer.
feedback the process by which an initial change brings about additional change that either reinforces or counteracts the initial change.
feedback path The signal path from the input of the bit-masking block to the output of the adaptive predictor. [T1.310-1991]
feeder echo noise Signal distortion resulting from reflected waves in a transmission line that is many wavelengths long and mismatched at both the generator and the load…
feeder link A radio link from an Earth station at a given location to a space station, or vice versa, conveying information for a space radiocommunication service…
Fence The boundary of a trusted region [CESG].
fence penetrability The ability of features outside a trusted region to penetrate a fence - thus leading to a potential or actual breach of the System Security Policy [CESG].
FEP Abbreviation for front-end processor.
Fermat's principle A principle stating that a ray of light follows the path that requires the least time to travel from one point to another, including reflections and…
FET photodetector A photodetector using photogeneration of carriers in the channel region of a field-effect transistor structure to provide photodetection with current gain.
fetch protection [An] AIS-provided restriction to prevent a program from accessing data in another user's segment of storage. [NIS] 2.
fiber (FY-ber) In food, fiber is the part of fruits, vegetables, legumes, and whole grains that cannot be digested. The fiber in food may help prevent cancer.
fiber amplifier A device that amplifies an optical signal directly, without the need to convert it to an electrical signal, amplify it electrically, and reconvert it to…
fiber axis The longitudinal center of symmetry of an optical fiber, i.e., the locus of points that are determined by the centers of mechanical symmetry of the…
fiber bandwidth See bandwidth (of an optical fiber).
fiber buffer See buffer.
fiber cable See fiber optic cable.
fiber cutoff wavelength (λcf) See cutoff wavelength.
fiber dispersion See dispersion.
Fiber Distributed Data Interface (FDDI) A media access (transmission) control-level protocol with token-ring architecture, a communication bandwidth of 100 Mbps and supported on a fiber network…
fiber optic bus See bus.
fiber optic cable A telecommunications cable in which one or more optical fibers are used as the propagation medium.
fiber optic isolator See optical isolator.
fiber optic link A communications link that transmits signals by means of modulated light propagated in an optical fiber.
fiber optics (FO) The branch of optical technology concerned with the transmission of light through fibers made of transparent materials such as glasses and plastics.