Telecommunications terms starting with P

636 terms

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 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…
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…
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.
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.
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…
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.
physical frame See frame.
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 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.
picowatt See yypW.
picowatt, psophometrically weighted See noise weighting.
picture Synonym image.
picture black In TV and facsimile, pertaining to the signal or signal level that corresponds to the darkest part, i.e.
Picture Element The smallest addressable unit on a display screen. The higher the resolution (the more rows of columns), the more information can be displayed.
picture frequency In analog facsimile systems, a baseband frequency generated by scanning an object.
picture white In TV and facsimile, pertaining to the signal level that corresponds to the brightest part, i.e.
piecewise linear encoding See segmented encoding law.
piecewise linear encoding law Synonym segmented encoding law.
piggyback entry Unauthorized access to a data processing system via an authorized user's legitimate connection. [2382-pt.8]
pigtail A short length of optical fiber that is permanently affixed to an active device, e.g.
pilot 1. A signal, usually a single frequency, transmitted over a communications system for supervisory, control, equalization, continuity, synchronization, or…
pilot frequency See synchronizing pilot.
pilot subcarrier 1. A subcarrier that serves as a control signal for use in the reception of FM stereophonic sound broadcasts. [47 CFR 73.310] 2.
pilot tone See pilot.
pilot-make-busy (PMB) circuit 1. A circuit arrangement by which trunks provided over a carrier system are made busy to the switching equipment in the event of carrier system failure…
PIN Noncancerous growth of cells lining the internal and external surfaces of the prostate gland.
PIN diode Acronym for positive-intrinsic-negative diode. A photodiode with a large, neutrally doped intrinsic region sandwiched between p-doped and n-doped…
PIN photodiode Synonym PIN diode.
Ping Ping is a computer network tool used to test whether a particular host is reachable across an IP network.
pink noise In acoustics, noise in which there is equal power per octave.
Piston A circular element that moves up and down the cylinder, compressing the air-fuel mixture in the top of the chamber, helping to produce horsepower.
Pitch Characters (or dots) per inch, measured horizontally.
pivot node The network element that routes a call to the release node, and informs the release node that it is capable of performing pivot functionality on that…
pixel Picture Element.
PKI Public Key Infrastructure - a system of administrative procedures and methods, combined with secure information technologies, that is used to manage…
PL/I A programming language that is designed for use in a wide range of commercial and scientific computer applications.
PLA (1) Peoples Liberation Army (Chinas army). (2) Patent License Agreement.
plain old telephone service (POTS) A call that requires nothing more than basic call handling. [T1.667-1999]
Plain Text The least formatted and therefore most portable form of text for computerized documents.
planar array An antenna in which all of the elements, both active and parasitic, are in one plane.
planar waveguide Synonym slab-dielectric waveguide.
Planck's constant The constant of proportionality, represented by the symbol h, that relates the energy E of a photon with the frequency of the associated wave through the…
Planck's law The fundamental law of quantum theory that describes the essential concept of the quanta of electromagnetic energy.
plane A part of the intelligent network conceptual model. [T1.667-1999]
plane polarization Synonym linear polarization.
plane wave A wave whose surfaces of constant phase are infinite parallel planes normal to the direction of propagation. 2.
Plant Station where mechanical, chemical, and/or nuclear energy is converted into electric energy.
plastic-clad silica (PCS) fiber An optical fiber that has a silica-based core and a plastic cladding. Note 1: The cladding of a PCS fiber should not be confused with the polymer overcoat…
plate modulation The modulation produced by introduction of the modulating wave into the plate circuit of any tube in which the carrier frequency wave is present.
platform A generic radar term, often used to encompass the pedestal and antenna assembly; sometimes including the radar control, display and analysis hardware and…
platform profile A profile whose focus is on functionality and interfaces for a particular type of platform (e.g.
Plenum The space between a hanging ceiling and the floor above or roof; usually contains HVAC ducts, electrical wiring, fire suppression system piping, etc.