- Отрасли: 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 radio propagation, a wave that is reflected from the ionosphere at a nearly vertical angle and that is used in short-range communications to reduce the area of the skip zone and thereby improve reception beyond the limits of the ground wave.
Industry:Telecommunications
In radio propagation, a region that is in the geometric shadow of an electromagnetic source, but into which propagation nonetheless takes place by virtue of the knife-edge effect described in Hygens' principle.
Industry:Telecommunications
In radio propagation by way of the ionosphere, the limiting frequency at or below which a wave component is reflected by, and above which it penetrates through, an ionospheric layer. 2. At vertical incidence, the limiting frequency at or below which incidence, the wave component is reflected by, and above which it penetrates through, an ionospheric layer. Note: The existence of the critical frequency is the result of electron limitation, i.e., the inadequacy of the existing number of free electrons to support reflection at higher frequencies.
Industry:Telecommunications
In radio or carrier systems in which no carrier is transmitted, e.g., single sideband or double sideband with suppressed carrier, the location in the frequency spectrum that the carrier would occupy if it were present.
Industry:Telecommunications
In radio net operations, the listening, by the net-control station, to the transmissions of stations in the net, particularly to check the quality of their transmissions. Note: Off-the-air monitoring is usually performed during periods when the net-control station is not transmitting. 2. The listening, by a radio station, to its own transmissions by receiving the signal that has been transmitted by the transmitting antenna, to discover the quality of the signal being transmitted to other stations or being broadcast. Note: In off-the-air monitoring, the received signal must have traveled through the air a reasonable distance from the transmitting antenna and not be a signal that is tapped on its way to the transmitting antenna internal to the station or in the antenna transmission line, i.e., the feeder. The monitoring distance should be such that direct inductive or capacitive coupling between the transmitting antenna and monitor antenna does not occur.
Industry:Telecommunications
In radio location systems, equipment that ascertains the distance between an interrogator and a transponder.
Industry:Telecommunications
In radio frequency usage, a device used to couple a balanced device or line to an unbalanced device or line.
Industry:Telecommunications
In radio communications, the ratio of the signal field strength obtained by diversity combining to the signal strength obtained by a single path. Note: Diversity gain is usually expressed in dB.
Industry:Telecommunications
In radio communications, the message part or parts that (a) precede the text, i.e., the message body, in time or space according to established conventions and (b) may include several data items, such as address groups, routing indicators, action addressee designators, information addressee designators, exempted addressee designators, prosigns, prowords, clear indicators, date-time groups, originator designators, special instructions, and protocol symbols. Note: Several message heading data items may be combined into a message preamble.
Industry:Telecommunications
In radio communications, the geographical area within which service from a radio communications facility can be received.
Industry:Telecommunications
