- 行业: Telecommunications
- Number of terms: 29235
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ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertainment and communications industry.
In satellite communications systems, a narrow beam from a satellite station antenna that illuminates, with high irradiance, a limited area of the Earth by using beam (directive) antennas rather than Earth-coverage antennas.
Industry:Telecommunications
In satellite communications system operations, a fixed communication channel access plan, as opposed to a demand assignment access plan in which allocation of accesses or the number of channels per access is varied in accordance with the demand.
Industry:Telecommunications
In route determination for packet-switched networks, adaptive routing in which an algorithm is used that (a) automatically routes traffic around congested, damaged, or destroyed switches and trunks and (b) allows the system to continue to function over the remaining portions of the network.
Industry:Telecommunications
In reception using heterodyning in the tuning process, the ratio of (a) the intermediate-frequency (IF) signal level produced by the desired input frequency to (b) that produced by the image frequency. Note 1: The image rejection ratio is usually expressed in dB. Note 2: When the image rejection ratio is measured, the input signal levels of the desired and image frequencies must be equal for the measurement to be meaningful. Synonym image frequency rejection ratio.
Industry:Telecommunications
In raster-scanned video displays, a scanning technique in which all odd-numbered scanning lines are first traced in succession, followed by the tracing of the even-numbered scanning lines in succession, each of which is traced between a pair of odd-numbered scanning lines. Note 1: The pattern created by tracing the odd-numbered scanning lines is called the odd field, and the pattern created by tracing the even-numbered scanning lines is called the even field. Each field contains half the information content, i.e., pixels, of the complete video frame. Note 2: Image flicker is less apparent in an interlaced display than in a noninterlaced display, because the rate at which successive fields occur in an interlaced display is twice that at which successive frames would occur in a noninterlaced display containing the same number of scanning lines and having the same frame refresh rate. Synonym interlacing.
Industry:Telecommunications
In raster-scanned video displays, a scanning technique in which all odd-numbered scanning lines are first traced in succession, followed by the tracing of the even-numbered scanning lines in succession, each of which is traced between a pair of odd-numbered scanning lines. Note 1: The pattern created by tracing the odd-numbered scanning lines is called the odd field, and the pattern created by tracing the even-numbered scanning lines is called the even field. Each field contains half the information content, i.e., pixels, of the complete video frame. Note 2: Image flicker is less apparent in an interlaced display than in a noninterlaced display, because the rate at which successive fields occur in an interlaced display is twice that at which successive frames would occur in a noninterlaced display containing the same number of scanning lines and having the same frame refresh rate. Synonym interlacing.
Industry:Telecommunications
In radio reception and retransmission, a repeater that converts the original band of frequencies of the received signal to a different frequency band for retransmission after amplification. Note: Heterodyne repeaters are used, for example, in microwave systems, to avoid undesired feedback between the receiving and transmitting antennas. Synonym IF repeater.
Industry:Telecommunications
In raster-scanned television technology, the period between (a) the end of one horizontal scanning line and the beginning of the next (the horizontal blanking interval,) or (b) the end of one field and the beginning of the next (the vertical blanking interval,) during which the display of picture information is suppressed. Note 1: Blanking intervals were a necessary part of the original NTSC and other, similar, television signal structures, which were based on the state of the art of electronics in the 1930s and even earlier. Both the camera and display (television receiver) were dependent upon specialized electron tubes that employed an electron beam that was swept (scanned) across the photosensitive or photoemissive area, respectively, of the tube in question. It was necessary that the beam be turned off during its return sweep (trace,) to avoid marring the image (trace. ) While television cameras based on charge-coupled devices (CCDs,) which have no such constraint, have supplanted cameras based on electron beams, most receivers still depend upon beam-based tubes. Note 2: To support a smooth transition (avoid obsolescence of older receivers) as the state of the art improved, the basic original signal structure was retained, with modifications (e.g., the superposition of signals necessary to support color. )
Industry:Telecommunications
In radiocommunications, an environment that is under the influence of extrinsic factors that degrade communications integrity, such as when (a) the benign communications medium is disturbed by natural or man-made events (such as an intentional nuclear burst,) (b) the received signal is degraded by natural or man-made interference (such as jamming signals or co-channel interference,) (c) an interfering signal can reconfigure the network, and/or (d) an adversary threatens successful communications, in which case radio signals may be encrypted in order to deny the adversary an intelligible message, traffic flow information, network information, or automatic link establishment (ALE) control information.
Industry:Telecommunications
In radio wave propagation, see F region. 2. In telecommunications networks and open systems architecture, a group of related functions that are performed in a given level in a hierarchy of groups of related functions. Note: In specifying the functions for a given layer, the assumption is made that the specified functions for the layers below are performed, except for the lowest layer.
Industry:Telecommunications
