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Starting in the Name of Allah, The Most Beneficent, The Most
Merciful
A channel is a path between two communication devices
Channel
Signaling transmission method Medium used Bandwidth: amount of data transmitted
in a fixed amount of time Direction(s) in which signal can flow Noise, attenuation, and distortion
characteristics
Characteristics
Signaling transmission methodAnalog: continuous varying waveforms to carry dataDigital:a.Two different values of electrical voltage or current b.On/off light sourcec.Frequently preferred because less susceptible to noise and interference
Directions Point to point channels
a. Simplex: channel passes data in one direction only
b. Half-duplex: transmits data one direction at a time (walkie-talkie)
c. Full-duplex: transmits data in both directions simultaneously (telephone)
Channel Organization
Multipoint: broadcasts messages to all connected receivers larger number of recievers
Transmission medium
MediazMaterials carrying the signala.Consists of two types:
i. Physical: wire cable ii. Wireless: Air
Physical Transmission Media
Twisted-pair cable
Coaxial cable
Fiber-optics
Twisted-pair cable
Cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources
Twisted-pair cable
c
twisted-pair cable twisted-pair wire
Coaxial cable A type of cable that has an inner
conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables also have an insulating outer sheath or jacket.
Fiber-optics
Its a flexible, transparent fiber made of high quality glass (silica) or plastic, slightly thicker than a human hair. It can function as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber
Fiber-optics
Fiber-optics
Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Fibers are used instead of metalwires because signals travel along them with less loss and are also immune to electromagnetic interference.
Fiber-optics
Wireless Transmission Media
Broadcast Radio a. Distribute signals through the
air over long distance b. Uses an antenna c. Typically for stationary
locations d. Can be short range
Wireless Transmission Media
Cellular Radioa. A form of broadcast radio
used for mobile communication
b. High frequency radio waves to transmit voice or data
Wireless Transmission Media
Microwaves a. Radio waves providing high
speed transmission b. They are point-to-point (can’t be
obstructed) c. Used for satellite communication
Wireless Transmission Media
Infrared (IR) a. Wireless transmission media that
sends signals using infrared light- waves
Wireless Transmission Media
Infrared (IR) a. Wireless transmission media that
sends signals using infrared light- waves