radiotelemetryTelemetry by means of radio waves. [NTIA] [RR]
radiotelephone callA telephone call, originating in or intended for a mobile station or a mobile Earth station, transmitted on all or part of its route over the…
radiotelephone distress frequencyAn international distress and calling frequency for mobile radiotelephone stations, survival craft, and emergency position-indicating radio beacons.
radiotelex callA telex call, originating in or intended for a mobile station or a mobile Earth station, transmitted on all or part of its route over the…
Rainbow Series[A] set of publications that interpret Orange Book requirements for trusted systems. [INFOSEC-99]
RAMRandom Access Memory - the hardware inside a computer that retains memory on a short-term basis and stores information while the user utilizes the…
Raman scatteringThe generation of many different wavelengths of light from a nominally single-wavelength source (a) by means of lasing action and interaction with…
random access discrete address (RADA)A communications technique in which radio users share one wide frequency band instead of each user's being assigned a narrow band.
random access memory (RAM)A read/write, nonsequential-access memory used for the storage of instructions and data.
random dataData that are (a) unpredictable and have no discernable pattern, or (b) satisfy certain mathematical criteria for statistical randomness.
random errorsErrors distributed over the signal in time so that they can be considered statistically independent from each other. [T1.226-1992]
random noiseNoise consisting of a large number of transient disturbances with a statistically random time distribution.
random numberA number selected from a known set of numbers in such a way that each number in the set has the same probability of occurrence. 2.
randomizerA device used to invert the sense of pseudorandomly selected bits of a bit stream to avoid long sequences of bits of the same sense.
RangeGeographic region in which a given plant or animal normally lives or grows.
rangingThe measurement of the distance to a remote object (target), from a known observation or reference point.
rasterA cellular data structure composed of rows and columns for storing images. Groups of cells with the same value represent features. See also grid.
raster countThe total number of raster scanning lines within a display space. [From Weik '89]
raster densityIn display systems, the number of scanning lines per unit distance perpendicular to the scanning direction. [From Weik '89]
raster scanningScanning in which the motion of the scanning spot follows a raster.
Rate AreaDenotes the smallest geographic area used to distinguish rate boundaries.
Rate CenterA geographically specified point used for determining mileage-dependent rates for PSTN calls. It is defined by a set of Vertical & Horizontal coordinates.
rated output powerThat power available at a specified output of a device under specified conditions of operation. Note: Rated output power may be further described; e.g.
RatingRating means evaluating a company, security, or investment product to determine how well it meets a specific set of objective criteria.
rayA geometric representation of a lightwave by a line normal to the electromagnetic wavefront; i.e., in the direction of propagation of the wave. [FAA]
Rayleigh distributionA mathematical statement, usually applied to frequency distributions of random variables, for the case in which two orthogonal variables are independent…
Rayleigh fadingIn electromagnetic wave propagation, phase-interference fading caused by multipath, and which may be approximated by the Rayleigh distribution.
Rayleigh ScatteringChanges in directions of electromagnetic energy by particles whose diameters are 1/16 wavelength or less.
RDFResource Description Framework. An XML-based language for describing online resources.
read1. [A] fundamental operation in an information system (IS) that results only in the flow of information from an object to a subject. [INFOSEC-99] 2.
read access1. In computer or data processing technology, the privilege (or capability) of reading electronically the information in a file or data base, without the…
read-only memory (ROM)1. A memory in which data, under normal conditions, can only be read. Synonym nonerasable storage.
read-only storageA storage device in which the contents cannot be modified, except by a particular user, or when operating under particular conditions, e.g.
read/write slotAn opening in the jacket of a diskette to allow access to the read/write heads. Synonym read/write opening.
readingThe acquisition or interpretation of data from a storage device, from a data medium, or from another source.
ready-for-data signalA call-control signal that is transmitted by the data circuit-terminating equipment (DCE) to the data terminal equipment (DTE) to indicate that the…
Real TimeWhen an event is reported as it happens - such as a quick jump in a stock's price or the constantly changing numbers on a market index - you are getting…
real-time reaction[In INFOSEC, the] immediate response to a penetration attempt that is detected and diagnosed in time to prevent access. [INFOSEC-99]
reasonable assuranceA high degree of confidence by an individual, entity, or application that received data should be treated as valid and unaltered. [After X9.30-1]
reasonableness checkA test to determine whether a value conforms to specified criteria. Note: A reasonableness check can be used to eliminate questionable data points from…
reattachAn action that re-establishes the communication with a participant of the conference. [T1.647-1995]
receive objective loudness rating (ROLR)The ratio in dB of the voltage entering a loop and telephone to the sound pressure produced by the telephone's receiver. [After T1.255-1997]
receive only (RO)Pertaining to a device or a mode of operation capable of receiving messages, but not of transmitting messages.
receive-after-transmit time delayThe time interval between (a) the instant of keying off the local transmitter to stop transmitting and (b) the instant the local receiver output has…
received noise powerThe calculated or measured noise power, within the bandwidth being used, at the receive end of a circuit, channel, link, or system. 2.
received signal level (RSL)The signal level at a receiver input terminal. Note 1: The signal bandwidth and the established reference level must be specified.
ReceiverThe component of a central receiver solar thermal system where reflected solar energy is absorbed and converted to thermal energy.
receiver attack-time delayThe time interval from (a) the instant a step rf signal, at a level equal to the receiver threshold of sensitivity, is applied to the receiver input to…
receiver overloadThe maximum acceptable value of the received average optical power consistent with a bit error ratio (BER) of 1 x 10-10 or better. [T1.646-1995]
receiver release-time delayThe time interval from removal of rf energy at the receiver input until the receiver output is squelched.
receiver sensitivityThe minimum value of average received power to achieve a 1 x 10-10 bit error ratio.
recipientAn Active Directory object that is mail-enabled, mailbox-enabled, or that can receive e-mail messages.
ReclamationThe process of restoring surface environment to acceptable pre-existing conditions.
recognized operating agency (ROA)Any operating agency, as defined in the ITU Convention (Geneva, 1992), which operates a public correspondence or broadcasting service and upon which the…
reconstructed sampleAn analog sample generated at the output of a decoder when a specified character signal is applied at its input.
reconstructed signalIn ADPCM (adaptive differential pulse code modulation), the sum of the signal estimate from adaptive prediction and the quantized difference signal from…
recordAll the documents and evidence plus transcripts of oral proceedings in a case.
record communicationA telecommunications process that produces an electronic message that is transmitted, received, stored or archived, and may be retrieved. 2.
record informationAll forms (e.g., narrative, graphic, data, computer memory) of information registered in either temporary or permanent form so that it can be retrieved…
record medium1. The physical medium on which information is stored in recoverable form. 2. In facsimile transmission, the physical medium on which the recorder forms…
record numberThe number that identifies a record within an extended frame (EF). [After T1.707-1998]
record pointerThe pointer which is used to address one record in an extended frame (EF). [After T1.707-1998]
record trafficTraffic that is recorded, in permanent or quasipermanent form, by the originator, the addressee, or both. 2.
recorder warning toneA half-second burst of 1400 Hz applied to a telephone line every 15 seconds to indicate to the called party that the calling party is recording the…
recording spotIn a facsimile recorder, the spot that is used to generate the recorded copy on the record medium.
RecoveryRestoration or return to health from sickness.
recovery procedure[The] action[s] necessary to restore data files of an information system (IS) and computational capability after a system failure. [INFOSEC-99]. 2.
RED[The] designation applied to information systems, and associated areas, circuits, components, and equipment in which national security information is…
RED signal[A] Telecommunications or automated information system signal that would divulge classified information if recovered and analyzed. [NIS] 2.
RED/BLACK concept[The] Separation of electrical and electronic circuits, components, equipment, and systems that handle national security information (RED), in electrical…
redirecting number (RN)A set of digits and related indicators (type of number, numbering plan identification, screening indicator, presentation indicator) that provide numbering…
RedirectionA system profile construction method of starting at a base platform and adding new services by allowing a service component to ask the base platform to…
reduced carrier single-sideband emissionA single-sideband emission in which the degree of carrier suppression enables the carrier to be reconstituted and to be used for demodulation. [NTIA] [RR]
reduced carrier transmissionA form of amplitude-modulation in which the carrier is transmitted at a controlled level below that which is required for demodulation, but at a level…
RedundancyThe inclusion of duplicate or alternate system elements to improve operational reliability by ensuring continued operation in the event that a primary…
redundancy checkA method of verifying that any redundant hardware or software in a communication system is in an operational condition. 2.
redundant codeA code using more signal elements than necessary to represent the intrinsic information. Note: The redundancy may be used for error-control purposes.
reference antennaAn antenna that may be real, virtual, or theoretical, and has a radiation pattern that can be used as a basis of comparison with other antenna radiation…
reference black level[In television,] The level corresponding to the specified maximum excursion of the luminance signal in the black direction. [47CFR]
reference circuitA hypothetical circuit of specified equivalent length and configuration, and having a defined transmission characteristic or characteristics, used…
reference clockA clock with which another clock is compared. 2. A clock, usually of high stability and accuracy, used to govern a network of mutually synchronized clocks…
reference color spaceThe geometric representation of colors in three-dimensional space. [CIE 845-03-25] Note: There are three reference spaces recognized by ISO 8613: CMYK…
reference configurationIn ISDN, a combination and arrangement of functional groups and reference points that reflect possible network topology.
reference data transferan information transfer between two server application processes acting cooperatively on instructions from a third application process.