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DESCRIBE THE PHYSICAL LAYER (2.1.2 Describe the fundamental principles of…
DESCRIBE THE PHYSICAL LAYER
2.1.1 Explain the purpose and funtions of the physical layer.
PURPOSE
Create the Electrical,optical or microwave signal that represents the bits in each frame.
FUNCTIONS
Actual carrier of information between computers.
Most important layer,as communication between computers cannot happen without physical layer.
Data is carried between every adjacent node(computers/routers) by transmission of electromagnetic/optical signal at the physical layer.
2.1.2 Describe the fundamental principles of physical layer.
ENCODING
a method of converting a stream of data bits into a predefined code
PHYSICAL COMPONENTS
the electronic hardware devices, media, and other connectors that transmit and carry the signals to represent the bits.
SIGNALLING
the physical layer must generate the electrical, optical, or wireless signals that
represent the "1" and "0" on the media
BANDWIDTH
Amount of data that can be transmitted in a fixed amount of time
For digital devices, the bandwidth is usually expressed in bits per second(bps) or bytes per second.
For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).
THROUGHPUT
Measure of how many units of information a system can process in a given amount of time.
Types Of Physical Media
Copper Cable
Unshielded twisted-pair (UTP)
Shield twisted-pair (STP)
Coaxial Cable
Fiber Optics
Fiber offers huge data bandwidth, protection to many types of noise and interference, and enhanced security.
Wireless
Wireless media include radio frequencies, microwave, satellite, and infrared