Communication Definitions
"A" to :Asc",
"Asy" to "Bc",
"Be" to "Bi",
"Bl" to "Cz",
"D" to "E",
"F" to "L",
"M" to "Mod",
"Mu" to "Nu",
"O" to "Z"
Form Factor: The size, shape or type of a device or equipment.
Ground loop: In an electrical system, an unwanted current that flows in a conductor connecting two points that are nominally at the same potential, i.e., ground, but are actually at different potentials. For example, the electrical potential at different points on the surface of the Earth can vary by hundreds of volts, primarily from the influence of the solar wind. Such an occurrence can be hazardous, e.g., to personnel working on long grounded conductors such as metallic telecommunications cable pairs. A ground loop can also exist in a floating ground system, one not connected to an Earth ground, if the conductors that constitute the ground system have a relatively high resistance, or have, flowing through them, high currents that produce a significant voltage(I x R) drop. 3: Ground loops can be detrimental to the operation of the electrical system. Contrast with ground current. [Ground Loop]
Ground plane: An electrically conductive surface that serves as the near-field reflection point for an antenna. A ground plane may consist of a natural (Earth or sea) surface, an artificial surface of opportunity (the roof of a motor vehicle), or a specially designed artificial surface (the disc of a discone antenna).
Half-Duplex: Operation in which communication between two terminals occurs in either direction, but in only one direction at a time.
Hamming Distance: The number of digit positions in which the corresponding digits of two binary words of the same length are different.
Handshaking: In data communications, a sequence
of events governed by hardware or software,
requiring mutual agreement of the state of the
operational modes prior to information exchange. GPIB for example sends out a Data Available signal but does not pass data until it receives a Ready for Data signal.
Read more on the Handshaking Protocol.
Harmonic: Of a sinusoidal wave, an integral multiple of the frequency of the wave.
Idle-channel noise: Noise that is present in a communications channel when no signals are applied. Note: The channel conditions and terminations must be stated for idle-channel noise measurements to be meaningful.
Inductive coupling: The transfer of energy from one circuit to another by virtue of the mutual inductance between the circuits. Inductive coupling may be deliberate and desired (as in an antenna coupler) or may be undesired (as in power line inductive coupling into telephone lines). Note 2: Capacitive coupling favors transfer of higher frequency components, whereas inductive coupling favors transfer of lower frequency components.
Local Area Network (LAN): A data communications system that (a) lies within a limited spatial area, (b) has a specific user group, (c) has a specific topology, and (d) is not a public switched telecommunications network, but may be connected to one. LANs are usually restricted to relatively small areas, such as rooms, buildings, ships, and aircraft. An interconnection of LANs within a limited geographical area, such as a military base, is commonly referred to as a campus area network. An interconnection of LANs over a city-wide geographical area is commonly called a metropolitan area network (MAN). An interconnection of LANs over large geographical areas, such as nationwide, is commonly called a wide area network (WAN). LANs are not subject to public telecommunications regulations.
Local orderwire: A communications circuit between a technical control facility and selected terminal or repeater locations within the communications complex. In multichannel radio systems, the local orderwire is usually a handset connection at the radio location.
