- Industry: Telecommunications
- Number of terms: 29235
- Number of blossaries: 0
- Company Profile:
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.
A high level description of the structure of a system, with security functions assigned to components within this structure.
Industry:Telecommunications
A high-speed multiplexing and switching method utilizing fixed-length cells of 53 octets to support multiple types of traffic. Note: ATM, specified in international standards, is asynchronous in the sense that cells carrying user data need not be periodic.
Industry:Telecommunications
A horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals (a) are guided or focused within the duct, (b) tend to follow the curvature of the Earth, and (c) experience less attenuation in the ducts than they would if the ducts were not present. Note: The reduced refractive index at the higher altitudes bends the signals back toward the Earth. Signals in a higher refractive index layer, i.e., duct, tend to remain in that layer because of the reflection and refraction encountered at the boundary with a lower refractive index material.
Industry:Telecommunications
A horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals (a) are guided or focused within the duct, (b) tend to follow the curvature of the Earth, and (c) experience less attenuation in the ducts than they would if the ducts were not present. Note: The reduced refractive index at the higher altitudes bends the signals back toward the Earth. Signals in a higher refractive index layer, i.e., duct, tend to remain in that layer because of the reflection and refraction encountered at the boundary with a lower refractive index material.
Industry:Telecommunications
A host computer that accepts terminal connections, usually from dial-up lines, and that allows the user to invoke Internet remote log-on procedures, such as Telnet.
Industry:Telecommunications
A host computer that participates in two separate networks. Note: A dual-homed host can provide security functions as a firewall. Synonym dual-homed gateway.
Industry:Telecommunications
A human authority which establishes a security policy and identifies the entities to which the policy applies.
Industry:Telecommunications
A hypothetical antenna that radiates or receives equally in all directions. Note: Isotropic antennas do not exist physically but represent convenient reference antennas for expressing directional properties of physical antennas.
Industry:Telecommunications
A hypothetical circuit of specified equivalent length and configuration, and having a defined transmission characteristic or characteristics, used primarily as a reference for measuring the performance of other, i.e., real, circuits or as a guide for planning and engineering of circuits and networks. Note: Normally, several types of reference circuits are defined, with different configurations, because communications are required over a wide range of distances. A group of related reference circuits is also called a reference system.
Industry:Telecommunications
A hypothetical mirror-image, i.e., virtual-image, of an antenna, i.e., antenna element, considered to extend as far below ground, i.e., the ground plane, as the actual antenna is above the ground plane. Note 1: The image antenna is helpful in calculating electric field vectors, magnetic field vectors, and electromagnetic fields emanating from the real antenna, particularly in the vicinity of the antenna and along the ground. Each charge and current in the real antenna has its image that may also be considered as a source of radiation equal to, but differently directed from, its real counterpart. Note 2: An image antenna may also be considered to be on the opposite side of any equipotential plane surface, such as a metal plate acting as a ground plane, analogous to the position of a virtual optical image in a plane mirror. Note 3: The ground plane need not be grounded to the Earth.
Industry:Telecommunications
