Answer
Wire, fiber-optic, or wireless (IR or RF).
-DJ Craig
Answer
Media used for communications:
- recorded media (books, newspapers, CD ROMS, memory sticks, etc) physically delivered from transmitter to receiver and decoded visually, mechanically, magnetically or electronically;
- air and other fluids (sound or pressure waves, light, IR, RF, often modulated)
- solids (mechanical motion or vibration, electrical signals, magnetic tapes and disks, visible light in glass)
- vacuum (RF, visible light)
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communication media (transmission media)are of two types:-
guided and unguided
guided communication media includes :-Twisted pair ,fiber optic ,coaxial cabel
unguided media includes: antenna ,Broad cast radio
Answer
Communication media (also called
transmission media or
communication channels) may be wired or wireless.
Wired media include
copper cables (e.g., twisted-pair copper wire cable - the "telephone cable", coaxial cable, UTP cable - the "LAN cable", etc.) and
optical fiber cables (made of glass or plastic). Copper cables allow the propagation of
electric signals (i.e., electric voltage or current pulses), whereas optical fiber cables allow the propagation of
light pulses.
Wireless media include the
free space, the
ionsphere, etc. Wireless media allow the propagation of
electromagnetic waves. The transmission/reception of electromagnetic waves requires the use of some
wireless link (also called
radio link, due to the fact that radio broadcast was one the first commercial wireless communication system in use), such as terrestrial microwave links, satellite links, etc.
Other types of channels include
storage media (e.g., hard disks, cd, dvd, etc.) and
underwater acoustic channels (which allow the propagation of
sound waves).
Communication channels vary in
capacity (i.e., the amount of information per time unit that can be carried in a reliable fashion),
attenuation (i.e., reducing of transmitted signal's strength; attenuation increases with the channel length),
distortion (i.e., alternation of signal's variation pattern, where is impressed the information),
noise (i.e., random unwanted signals that corrupt the signal shape), etc.
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