Telecommunications terms starting with A

604 terms

  1. analog computer A device that performs operations on data that are represented within the device by continuous variables having a physical resemblance to the quantities…
  2. analog data Data represented by a physical quantity that is considered to be continuously variable and has a magnitude directly proportional to the data or to a…
  3. analog decoding The portion of the digital-to-analog conversion process that generates an analog signal value from the digital signal that resulted from analog encoding.
  4. analog encoding The portion of the analog-to-digital conversion process that samples an analog signal and creates a digital signal that represents the value of the sample.
  5. analog facsimile equipment Facsimile equipment in which (a) analog techniques are used to encode the image detected by the scanner and (b) the output is an analog signal.
  6. analog signal A signal, such as voice, that varies in a continuous manner.
  7. analog signaling data link The data link that provides an interface to signaling terminals and is made up of voice-frequency analog transmission channels and modems. [T1.110.2-1992]
  8. analog switch Switching equipment designed, designated, or used to connect circuits between users for real-time transmission of analog signals.
  9. analog transmission Transmission of a continuously varying signal as opposed to transmission of a discretely varying signal.
  10. analog-to-digital (A-D) coder Synonym analog-to-digital converter (ADC).
  11. analog-to-digital (A-D) encoder Synonym analog-to-digital converter (ADC).
  12. analog-to-digital converter (ADC) A device that converts an analog signal to a digital signal that represents equivalent information.
  13. analytical attack An attempt to break a code or to find a key using analytical methods. Note: Examples of an analytical attack are: a statistical analysis of patterns; a…
  14. angle modulation Modulation in which the phase or frequency of a sinusoidal carrier is varied. Note: Phase and frequency modulation are particular forms of angle…
  15. angle of deviation In optics, the net angular deflection experienced by a light ray after one or more refractions or reflections.
  16. Angle of Incidence In reference to solar energy systems, the angle at which direct sunlight strikes a surface; the angle between the direction of the sun and the…
  17. angstrom (Å) A unit of length equal to 10-10 m. Note 1: The angstrom is not an SI (International System) unit, and it is not accepted for government use (Fed. Std.
  18. angular misalignment loss Power loss caused by the deviation from optimum angular alignment of the axes of source to waveguide, waveguide to waveguide, or waveguide to detector.
  19. ANI Abbreviation for automatic number identification.
  20. anisochronous Pertaining to transmission in which the time interval separating any two significant instants in sequential signals is not necessarily related to the time…
  21. anisochronous transmission See asynchronous transmission.
  22. anisotropic Pertaining to a material whose electrical or optical properties vary with (a) the direction of propagation of a traveling wave or with (b) different…
  23. ANOMALOUS PROPAGATION (AP) Non-standard atmospheric temperature or moisture gradients will cause all or part of the radar beam to propagate along a non-normal path.
  24. anonymous call A 7- or 10-digit call to the directory number of the public service answering point (PSAP) (where applicable) causing the E911 system (emergency 9-1-1…
  25. anonymous FTP The name of a file-transfer protocol that allows a user on one host to access and transfer files to and from another host over a network. [After 2382-pt.
  26. ANS The part of the nervous system that controls muscles of internal organs (such as the heart, blood vessels, lungs, stomach, and intestines) and glands…
  27. ANSI American National Standards Institute - a private, non-profit organization that administers and coordinates the U.S.
  28. ANSI/EIA/TIA-568 A U.S. industry standard that specifies a generic telecommunications cabling system, which will support a multiproduct, multivendor environment, for…
  29. answer back A signal sent by receiving equipment to the sending station to indicate that the receiver is ready to accept transmission.
  30. answer indicator A signal indicating acceptance of the call by the addressed user. [T1.507-1996]
  31. answer signal A supervisory signal returned from the called telephone to the originating switch when the call receiver answers.
  32. Answer/Disconnect Supervision The term "Answer/Disconnect Supervision" denotes the transmission of the switch trunk equipment supervisory signal (off-hook or on-hook) to the customer's…
  33. antenna Any structure or device used to collect or radiate electromagnetic waves. 2. A device that converts radio frequency electrical energy to radiated…
  34. antenna aperture See aperture.
  35. antenna array An assembly of antenna elements with dimensions, spacing, and illumination sequence such that the fields for the individual elements combine to produce a…
  36. antenna blind cone The volume of space, usually approximately conical with its vertex at the antenna, that cannot be scanned by an antenna because of limitations of the…
  37. antenna coupler A device used to match the impedance of a transmitter and/or receiver to an antenna to provide maximum power transfer.
  38. antenna dissipative loss A power loss resulting from changes in the measurable impedance of a practical antenna from a value theoretically calculated for a perfect antenna.
  39. antenna effective area The functionally equivalent area from which an antenna directed toward the source of the received signal gathers or absorbs the energy of an incident…
  40. antenna efficiency The ratio of the total radiated power to the total input power. Note: The total radiated power is the total input power less antenna dissipative losses.
  41. antenna electrical beam tilt The shaping of the radiation pattern in the vertical plane of a transmitting antenna by electrical means so that maximum radiation occurs at an angle…
  42. ANTENNA GAIN The measure of effectiveness of a directional antenna as compared to an isotropic radiator, maximum value is called antenna gain by convention.
  43. antenna gain-to-noise-temperature (G/T) In the characterization of antenna performance, a figure of merit, where G is the antenna gain in decibels at the receive frequency, and T is the…
  44. antenna height above average terrain The antenna height above the average terrain elevations from 3.2 to 16 kilometers (2 to 10 miles) from the antenna for the eight directions spaced evenly…
  45. antenna lobe A three-dimensional section of the radiation pattern of a directional antenna, bounded by one or more cones of nulls or by regions of diminished…
  46. antenna matching The process of adjusting impedance so that the input impedance of an antenna equals or approximates the characteristic impedance of its transmission line…
  47. antenna noise temperature The temperature of a hypothetical resistor at the input of an ideal noise-free receiver that would generate the same output noise power per unit bandwidth…
  48. anti-clockwise polarized wave Synonym left-hand polarized wave.
  49. anti-interference Pertaining to equipment, processes, or techniques used to reduce the effect of natural and man-made noise on radio communications.
  50. anti-jam Measures ensuring that intended transmitted information can be received despite deliberate jamming attempts. [INFOSEC-99]
  51. anti-node A point in a standing wave at which the amplitude is a maximum.
  52. anti-spoof Measures taken to prevent an unauthorized person/entity from impersonating an authorized person/entity to gain access to a data system. [DoJ] 2.
  53. anti-virus program A computer program designed to detect computer-file viruses and possibly to suggest or take corrective action. Synonym vaccine program. [After 2382-pt.8]
  54. Antireflection Coating A thin coating of a material applied to a photovoltaic cell surface that reduces the light reflection and increases light transmission.
  55. anycall In adaptive high-frequency (HF) radio automatic link establishment, a broadcast in which (a) the called stations are unspecified, (b) stations receiving…
  56. AP analysis plan.
  57. APC A cell that shows an antigen on its surface to other cells of the immune system. This is an important part of an immune response.
  58. APD On a buoy report, the average wave period (seconds) of all waves during the 20-minute period.
  59. aperiodic antenna An antenna designed to have an approximately constant input impedance over a wide range of frequencies.
  60. Aperture An opening; in solar collectors, the area through which solar radiation is admitted and directed to the absorber.
  61. aperture correction 1. In a scanned image system, electrical compensation for the distortion introduced by the limiting size of a scanning aperture. [IEEE 100; After SMPTE] 2.
  62. aperture distortion In facsimile, the distortion of the recorded image caused by the shape and finite size of the scanning and recording apertures.
  63. aperture illumination 1. The field distribution, in amplitude and phase, over the antenna physical aperture. 2.
  64. aperture-to-medium coupling loss The difference between the theoretical gain of a very large antenna, such as the antennas in beyond-the-horizon microwave links, and the gain that can be…
  65. Apogee The farthest distance between the moon and earth or the earth and sun.
  66. apogee altitude See altitude of the apogee or of the perigee.
  67. app Abbreviation for application, application software.
  68. apparent power In alternating-current power transmission and distribution, the product of the rms voltage and amperage.
  69. applet Applets are Java programs based around the Applet or JApplet classes. They are most closely associated with the ability to provide active content within…
  70. Application Under the Equal Credit Opportunity Act (ECOA), an oral or written request for an extension of credit that is made in accordance with the procedures…
  71. application association A cooperative relationship between two application entities, formed by their exchange of application protocol control information through their use of…
  72. application entity (AE) The system-independent application activities that are made available as application services to the application agent, e.g.
  73. Application Layer See Open Systems Interconnection--Reference Model.
  74. application platform Synonym platform.
  75. application program See application.
  76. Application Program Interface (API) An API is a set of system calls or routines for application programs to access services from operating systems or other programs.
  77. application protocol A set of rules and formats (semantic and syntactic) that determines the communication behavior of application entities in the performance of application…
  78. application service element (ASE) A coherent set of integrated functions to help accomplish application communication, e.g., within an application entity. [T1.667-1999]
  79. application software 1. Synonym application. 2. Software that is specific to an application and is composed of programs, data and documentation [POSIX.0].
  80. applique Circuit components added to an existing system to provide additional or alternate functions.
  81. appointment book A small (pocket-size or smaller), specialized, portable computing device, with a self-contained power source, designed to (a) accept as inputs; (b) store…
  82. approved circuit Deprecated synonym for protected distribution system.
  83. aramid yarn Generic name for a tough synthetic yarn that is often used in optical cable construction for the strength member, protective braid, and/or rip cord for…
  84. architecture The term architecture refers to the hardware, software or combination of hardware and software comprising a computer system or network.
  85. archive file A software file that has been set aside, often in a redundant storage medium, as a security measure or for later retrieval, e.g.
  86. archiving reducing the strain of storing data by backing it up, removing it from its native environment, and storing it elsewhere. [...
  87. area broadcast shift The changing from listening to transmissions intended for one broadcast area to listening to transmissions intended for another broadcast area.
  88. area code See access code, code, country code, N code.
  89. area loss When optical fibers are joined by a splice or a pair of mated connectors, a power loss that is caused by any mismatch in size or shape of the cross…
  90. argument Information passed to a method. Arguments are also sometimes called parameters.
  91. arithmetic and logic unit (ALU) A part of a computer that performs arithmetic, logic, and related operations.
  92. arithmetic overflow In a digital computer, the condition that occurs when a calculation produces a result that is greater than a given register or storage location can store…
  93. arithmetic register A register that holds the operands or the results of operations such as arithmetic operations, logic operations, and shifts.
  94. arithmetic shift A shift, applied to the representation of a number in a fixed radix numeration system and in a fixed-point representation system, and in which only the…
  95. arithmetic underflow In a digital computer, the condition that occurs when a calculation produces a non-zero result that is less than the smallest non-zero quantity that a…
  96. arithmetic unit In a processor, the part that performs arithmetic operations; sometimes the unit performs both arithmetic and logic operations.
  97. Armed Forces Radio Service (AFRS) A radio broadcasting service that is operated by and for the personnel of the armed services in the area covered by the broadcast.
  98. armor Of a communications cable, a component intended to protect the critical internal components, e.g.
  99. ARP address resolution protocol.
  100. ARPANET ARPA Network.