Technology — page 138 of 206

20,531 terms including subtopics (0 terms filed directly here)

Technology terms

phase detector A circuit or instrument that detects the difference in phase between corresponding points on two signals.
phase deviation In phase modulation, the maximum difference between the instantaneous phase angle of the modulated wave and the phase angle of the unmodulated carrier.
phase diagram A graphic representation of the phase relationships between two or more waveforms.
phase difference The time interval or phase angle by which one wave leads or lags another. Synonym phase offset.
phase distortion Distortion that occurs when (a) the phase-frequency characteristic is not linear over the frequency range of interest, i.e.
phase equalizer See delay equalizer.
phase flux reversal In phase-encoded recording, a magnetic flux reversal written at the nominal midpoint between successive "1" bits, or between successive "0" bits, to…
phase hit See yyhit.
phase instability The fluctuation of the phase of a wave, relative to a reference. Note: The fluctuation is often from unknown causes.
phase interference fading The variation in signal amplitude produced by the interaction of two or more signal elements with different relative phases.
phase inversion Introduction of a phase difference of 180°. Note: Phase inversion may occur with a random or periodic, symmetrical or non-symmetrical waveform, although…
phase jitter Rapid, repeated phase perturbations that result in the intermittent shortening or lengthening of signal elements.
phase jump A sudden phase change in a signal.
phase linearity Direct proportionality of phase shift to frequency over the frequency range of interest.
phase measurement tolerance The maximum allowable difference between a phase measurement and the actual phase value.
phase modulation (PM) Angle modulation in which the phase angle of a carrier is caused to depart from its reference value by an amount proportional to the instantaneous value…
phase noise In an oscillator, rapid, short-term, random fluctuations in the phase of a wave, caused by time-domain instabilities.
phase nonlinearity Lack of direct proportionality of phase shift to frequency over the frequency range of interest.
phase offset Synonym phase difference.
Phase One Engineering Team (POET) OBSOLETE. An FFRDC providing technical support to the Phase I Program Office. Now referred to as POET.
phase perturbation Any shifting (often quite rapid), from whatever cause, in the phase of a signal. Note 1: The shifting in phase may appear to be random, cyclic, or both.
phase quadrature See quadrature.
phase shift The change in phase of a periodic signal with respect to a reference.
phase term In the propagation of an electromagnetic wave in a uniform waveguide, such as an optical fiber or metal waveguide, the parameter that indicates the phase…
phase transients Perturbations in phase of limited duration seen at synchronization interfaces. Typical duration is several time constants of the slave clock which…
phase velocity The velocity of propagation of a uniform plane wave, given by (a) the product of the wavelength and the frequency divided by (b) the refractive index of…
phase-encoded (PE) recording Binary recording on magnetic media, such as magnetic disks, tapes, and cards, in which a "1" is represented by a magnetic flux reversal to the polarity of…
phase-frequency characteristic A Cartesian-coordinate plot of phase shift as the dependent variable, versus frequency as the independent variable.
phase-frequency distortion Synonym phase distortion.
phase-locked loop (PLL) An electronic circuit that controls an oscillator so that it maintains a constant phase angle relative to a reference signal.
phase-shift keying (PSK) In digital transmission, angle modulation in which the phase of the carrier is discretely varied in relation either to a reference phase or to the phase…
phase-shift signaling Synonym phase-shift keying.
Phased Array The arranging of radiating or receiving elements that, although physically stationary, is electronically steer-able and can switch rapidly from one target…
Phased Array Tracking Radar Intercept On Target (missile) (PATRIOT) A point or limited area defense system originally built to intercept aircraft. PAC-3 improvements, which will give it greater capability against theater…
Phased Deployment The sequential steps of element deployments leading to a designated system capability that is realizable with fiscal and technological constraints.
phasing In facsimile transmission and reception, the process by which the start of the scanning line or lines is made to correspond to one edge of the object…
Phenomenology The topological classification of a class of phenomena. Phenomenology efforts collect and analyze optical and radar signature data, and model phenomena…
PHI Photonic Hit Indicator.
PHIGS Programmers Hierarchical Interactive Graphics System.
Phishing When internet fraudsters impersonate a business in an attempt to trick you into giving out your personal information, such as usernames, passwords, and…
phishing confidence level A property of each e-mail message that the Office Outlook 2003 Junk E-mail Filter stamps as a property on the message when it is processed in the Outlook…
phon In acoustics, a unit of subjective loudness level equal to the sound pressure level in dB compared to that of an equally loud standard sound.
phone Abbreviation for telephone, telephony. 2. Loosely, the voice-operation mode in radio communications.
phonetic alphabet A list of standard words used to identify letters in a message transmitted by radio or telephone.
phonetic index A listing organized by the sound of a word rather than its spelling
Phonetic search Phonetic search is the analysis of words that are pronounced similarly in order to detect all possible variants.
phonon A quantum of acoustic energy, the level of which is a function of the frequency of the acoustic wave.
phonon absorption Absorption of light energy by its conversion to vibrational energy. Note: Phonon absorption determines the fundamental, i.e.
PHOTINT Photographic Intelligence.
photo laboratory process The chemical process of converting a latent image in an emulsion layer to a visible, stable image.
Photochemical A chemical reaction resulting from exposure to radiant energy or light. 224
photoconductive effect In certain materials, the phenomenon that results in photoconductivity.
photoconductivity In certain materials, the increase in electrical conductivity that results from increases in the number of free carriers generated when photons are…
Photocurrent An electric current induced by radiant energy.
photodetector (PD) A transducer capable of accepting an optical signal and producing an electrical signal containing the same information as in the optical signal.
photodiode A semiconductor diode that produces, as a result of the absorption of photons, (a) a photovoltage or (b) free carriers that support the conduction of…
Photoelectric Effect The process whereby a gamma ray (or x-ray photon) with energy somewhat greater than that of the binding energy of an electron in an atom, transfers all…
Photogrammetry Techniques of obtaining precise measurements from images. This process can derive elevation from specially created stereo pairs of aerial photos.
photographic records Records that take the form of pictures or photographs, sometimes with related textual records.
Photon A photon is both a wave and a particle. A beam of light is composed of these particles.
photon noise In an optical communication link, noise attributable to the statistical nature of optical quanta. [FAA] See quantum noise.
photonic Referring to or using opto-electronic, electro-optic, or magneto-optic phenomena.
photonic computer A variety of computer in which the electronic circuits (which process data serially) are replaced by faster and more powerful photonic circuits (which can…
photonic switching The use of photonic devices rather than electronic devices to make or break connections within integrated circuits.
photonics The science of generating and harnessing light as well as other forms of radiant energy whose quantum unit is the photon.
photosensitive recording Facsimile recording by the exposure of a photosensitive surface to a signal-controlled light beam or spot.
photovoltaic effect The production, as a result of the absorption of photons, of a voltage difference across a pn junction.
PHP PHP Hypertext Preprocessor is an open source server side scripting language used to render web pages or add interactivity to them. See also: PHP.net
Phrase detection The recognition and grouping of an idiom such as "home run" or "Christmas tree".
Phrase Match Phrase Match is a form of keyword matching where an ad will be displayed if the user's search query includes the exact phrase, even if their query…
Phrase search A search for documents containing a exact sentence or phrase specified by a user.
Phrase searching A search engine may provide an option to search a set of words as a phrase, either by typing in quotation marks (""), by using a command or clicking a…
Phrasing The recognition and grouping of an idiom such as "home run" or "Christmas tree."
PHS&T Packaging, Handling, Storage, and Transportation.
Physical Agents Descriptive term that includes non-ionizing EMR, static electric and magnetic fields, ionization radiation, energy beams, noise, explosions, de-orbiting…
physical computer A hardware-based computer, as opposed to a software-based virtual machine.
Physical Configuration Audit (PCA) Physical examination to verify that the configuration item(s) as built conforms to the technical documentation that defines the item.
Physical CPU A processor within a physical machine. See also Virtual CPU.
Physical custody a form of child custody that grants one parent the right to live with the child.
physical data replication An on-line data replication method that duplicates I/O writes to another disk on a physical block basis.
physical disk A hard disk drive in a virtual machine that is mapped to a physical drive or partition on the host machine.
physical file name The address or the location of a copy of a file on a storage system.
physical frame See frame.
physical inventory process of identifying all tangible records of an organization See also records inventory.
Physical Layer See Open Systems Interconnection--Reference Model. 2. The layer (layer 1) that provides transparent transmission of a bit stream over a circuit built from…
physical name A unique label AWS CloudFormation assigns to each resource when creating a stack.
physical optics The branch of optics that treats light propagation as a wave phenomenon rather than a ray phenomenon, as in geometric optics.
physical plane The plane in the intelligent network conceptual model containing elements and their interfaces that implement functional entities. [T1.667-1999]
physical security 1. The measures used to provide physical protection of resources against deliberate and accidental threats [7498-2]. 2. See communications security.
physical signaling sublayer (PLS) In a local area network (LAN) or a metropolitan area network (MAN) using open systems interconnection (OSI) architecture, the portion of the physical…
physical topology The physical configuration, i.e., interconnection, of network elements, e.g., cable paths, switches, concentrators.
Physically Isolated Network A network that is not connected to entities or systems outside a physically controlled space.
PI Program Integrator.
PIA Personnel Identification/Authorization System (USA term).
PIC (1) PLRS Interface Controller (US Army term). (2) Policy Integration Committee. (3) Program Information Center (Computer programmer term).
pick list A list containing specific records that are to be retrieved
Pickup directory A directory that receives RFC-822 compliant files from the file system for the purpose of creating message objects that can be passed to the Submission…
picowatt See yypW.
picowatt, psophometrically weighted See noise weighting.
Pictometry Shows high resolution images taken at oblique angles of about 45 degrees from the four compass points and from directly above.