Technology terms starting with S

2,256 terms

  1. spectral bandwidth See spectral width.
  2. Spectral Density A radar term for the distribution of power by frequency.
  3. Spectral Irradiance The monochromatic irradiance of a surface per unit bandwidth at a particular wavelength, usually expressed in Watts per square meter-nanometer bandwidth.
  4. Spectral Line An emission (bright) or absorption (dark) of light at a specific frequency or wavelength.
  5. spectral loss curve Of an optical fiber, a plot of attenuation as a function of wavelength. Note: Spectral loss curves must be normalized with respect to distance before…
  6. spectral purity The degree to which a signal is monochromatic.
  7. spectral radiance Radiance per unit wavelength interval at a given wavelength, expressed in watts per steradian per unit area per wavelength interval.
  8. spectral responsivity The ratio of an optical detector's electrical output to its optical input, as a function of optical wavelength.
  9. spectral width A measure of the spread of the Doppler spectrum and consequently is sensitive to the spread in the particle size spectra.
  10. spectral window See window.
  11. Spectrum Electromagnetic radiation arranged in order of wavelength from Ion wavelength radio waves to short wavelength gamma rays.
  12. spectrum designation of frequency See electromagnetic spectrum.
  13. spectrum signature The pattern of radio signal frequencies, amplitudes, and phases, which pattern characterizes the output of a particular device and tends to distinguish it…
  14. Specular reflection Also known as direct reflection, regular reflection, or mirror reflection. The reflection of electromagnetic rays without scattering or diffusion.
  15. speech digit signaling Synonym bit robbing.
  16. speech level The power in dBm of a speech signal measured using a technique equivalent to Method B of ITU-T Recommendation P.56. [T1.255-1997]
  17. speech power See volume unit.
  18. speech privacy Techniques using fixed sequence permutations or voice/speech inversion to render speech unintelligible to the casual listener. [INFOSEC-99]
  19. Speech Recognition A technology that enables a machine to recognize spoken words. Speech recognition is not a biometric technology.
  20. speech synthesizer A device that is capable of accepting digital or analog data and developing intelligible speech sounds that correspond to the input data, without…
  21. speech-plus Pertaining to a circuit that was designed and used for speech transmission, but to which other uses, such as digital data transmission, facsimile…
  22. speech-plus-duplex operation Operation in which speech and telegraphy (duplex or simplex) are transmitted simultaneously over the same circuit, and mutual interference is eliminated…
  23. speech-plus-signaling Pertaining to equipment that permits the use of part of a voice-frequency band for signaling.
  24. speech-to-speech-correlated-noise ratio (Q) The ratio of the speech power to the power of speech-correlated noise in a digital transmission system. [T1.501-1988]
  25. SPEED System Planning, Engineering, and Evaluation Device.
  26. speed calling A service feature that enables a switch or station to store certain telephone numbers and dial them automatically when a short (1-, 2-, or 3-digit) code…
  27. speed dialing 1. Synonym abbreviated dialing. 2. Dialing at a speed greater than the normal ten pulses per second.
  28. speed of light (c) The speed of an electromagnetic wave in free space, precisely 299,792,458 m/s. Note 1: The preceding figure is precise because by international agreement…
  29. speed of service The time between release of a message by the originator to receipt of the message by the addressee, as perceived by the end user.
  30. speed-up tone Synonym camp-on busy signal.
  31. Spell Check Checks an email message before sending allowing you to correct any spelling errors.
  32. Spell Check Optimization The process of optimizing a spell check dictionary towards a live search index.
  33. Spell checking Individual query terms and phrases are spell-checked against a dictionary. The spell check algorithm is normally based on the edit distance between a…
  34. SPF A scale for rating the level of sunburn protection in sunscreen products. The higher the SPF, the more sunburn protection it gives.
  35. SPF (sender policy framework) An extension of the SMTP protocol that prevents spammers from forging the From: fields in e-mail messages by verifying that the IP address in the SMTP…
  36. SPFE Special Projects Flight Experiments.
  37. SPICE Space Integrated Controls Experiment.
  38. Spider Search engine crawlers which search or "spider" the web for pages to include in the index.
  39. Spider trap An infinite loop that a spider may get caught in if it explores a dynamic site where the URLs of pages keep changing.
  40. Spider, Spyder That part of a search engine which surfs the web, storing the URLs and indexing the keywords and text of each page it finds...
  41. Spidering The process of surfing the web, storing URLs and indexing keywords, links and text.
  42. spike 1. An inflorescence in which the main axis is elongated and the flowers are sessile. 2.
  43. spike file See last-in first-out.
  44. spill forward In automatic switching, the transfer of full control on a call to the succeeding office by sending forward the complete telephone address of the called…
  45. spill-forward feature A service feature, in the operation of an intermediate office, that, acting on incoming trunk service treatment indications, assumes routing control of…
  46. spillover In an antenna, the part of the radiated energy from the feed that does not impinge on the reflectors.
  47. SPIMS Strategic Program Information Management System (SDIO/MDA term). 274
  48. SPINE The bones, muscles, tendons, and other tissues that reach from the base of the skull to the tailbone.
  49. SPINS Special Instructions (JFACC term).
  50. Spiral Development An iterative process for developing a defined set of capabilities within one increment.
  51. spiral track A track with a spiral shape written on a diskette, as part of a method of copy protection. [2382-pt.8]
  52. spiral wrap A molded, insulated plastic product in the form of a helix, used to contain or dress electrical wiring, e.g.
  53. spiral-four cable A quadded cable with four conductors. Synonym star quadded cable.
  54. SPIRE Space Performance in Radiation Environments.
  55. SPIRIT As opposed to a ghost (see above), a spirit is normally the soul of the deceased that has crossed over, and exists in a spiritual or metaphysical plane.
  56. Splash page Similar to a gateway page but provides an initial display which must be viewed before a visitor reaches the main page.
  57. splice To join, permanently, physical media that conduct or transmit power or a communication signal. 2. A device that so joins conducting or transmitting media.
  58. splice closure A usually weatherproof encasement, commonly made of tough plastic, that envelops the exposed area between spliced cables, i.e.
  59. splice loss In fiber optic systems, any loss of optical power at a splice. Note: A practical splice, of physically realizable fibers, has losses attributable to a…
  60. splice organizer In optical communication, a device that facilitates the splicing or breaking out of fiber optic cables.
  61. spline A mathematical curve used to smoothly represent spatial variation. A spline operation inserts vertices to create a curve in an arc.
  62. split 1. With respect to a signal, to divert a portion of it, or divide it, into usually predetermined or specified proportions. 2.
  63. split access token A combination of full access token and filtered access token linked together by the local security authority (LSA) component of the operating system.
  64. split brain syndrome Split brain syndrome occurs when all networks designated to carry internal cluster communications fail, and nodes cannot receive heartbeat signals from…
  65. split homing The connection of a terminal facility to more than one switching center by separate access lines, each of which has a separate directory number.
  66. Split Knowledge A procedure whereby a cryptographic key is handled as multiple key components from the time that the key or the separate key components are generated…
  67. split screen On a display device, display space that has been divided into two or more areas, so that each area can display different portions of the same file or…
  68. splitter See directional coupler, T-coupler, tee coupler.
  69. Splog Spam blog, typically consisting of stolen or automated low quality content.
  70. SPM Software Programmers Manual.
  71. SPO See System Program Office. (Air Force)
  72. SPOCK Security Proof of Concept Keystone.
  73. SPOD Seaport of Debarkation.
  74. SPOE Seaport of Embarkation.
  75. SPOF (Single Point of Failure) A component of a cluster or node that, if it fails, affects access to applications or services. See also multiple points of failure.
  76. Spoliation Generally, the intentional or negligent destruction or alteration of evidence when there is current litigation or an investigation or there is reasonable…
  77. Sponsor An individual or business establishment that financially supports a race driver, team, race or series of races in return for advertising and marketing…
  78. sponsor certificate A certificate that indicates the restrictions on those documents and transactions that an entity may authorize. [After X9.45]
  79. spontaneous emission Radiation emitted when the internal energy of a quantum mechanical system drops from an excited level to a lower level without regard to the simultaneous…
  80. spoofed mail An e-mail message whose sending address has been modified to appear as though it originates from a sender other than the actual sender of the message.
  81. Spoofing Some market analysts maintain that the increased volatility in stock markets may be the result of an illegal practice known as spoofing, or phantom bids.
  82. Spool/Queue A directory on the mail server that holds emails before they are viewed or downloaded from a client.
  83. spooling The use of auxiliary storage as buffer storage to reduce processing delays when transferring data between peripheral equipment and the processors of a…
  84. Sporadic E In solar-terrestrial terms, a phenomenon occurring in the E region of the ionosphere, which significantly affects HF radiowave propagation.
  85. sporadic E propagation Synonym sporadic E.
  86. SPOT Systeme Probatoire dObservation de la Terre - French observation satellite
  87. spot beam In satellite communications systems, a narrow beam from a satellite station antenna that illuminates, with high irradiance, a limited area of the Earth by…
  88. Spot Instance A purchase option available to AWS users. In essense, users can bid on spare Amazon EC2 instances and purchase them if their bid exceeds the current Spot…
  89. spot jamming The jamming of a specific channel or frequency. [JP 1-02]
  90. spot projection In facsimile systems, optical scanning in which a scanning spot is moved across the object and the scanning spot size is determined by the illuminated…
  91. spot size The size of the electron spot on the face of a cathode ray tube. Note: The spot size is larger than the diameter of the electron beam because of the…
  92. spot speed In facsimile systems, the speed of the scanning or recording spot along the available line.
  93. SPP System Performance Parameters.
  94. SPR (1) Secretarial Program Review (AF). (2) Secretarial Performance Review (OSD). (3) Sponsors Program Review (Navy).
  95. spread spectrum Telecommunications techniques in which a signal is transmitted in a bandwidth considerably greater than the frequency content of the original information.
  96. Sprint Nuclear-armed, short-range interceptor used in SAFEGUARD/Sentinel systems.
  97. SPRM Solid Propellant Rocket Motor.
  98. SPRN (Former) Soviet system for missile attack warning.
  99. SPS Severe Weather Potential Statement
  100. SPT Support.