TRANSMISSION Media used in physical layer, Slides of Computer Networks

Download TRANSMISSION Media used in physical layer and more Slides Computer Networks in PDF only on Docsity!

Data Transmission :  Communication by propagation and processing of signals  Signals are electric/electromagnetic reprasentation of data Transmission system :  Transmitter +Reciever+Transmission medium Transmission medium  Physical path between transmitter and receiver

Bandwidth Higher bandwidth gives higher data rate Transmission impairments Attenuation Interference Number of receivers ◦ (^) In guided media ◦ (^) More receivers (multi-point) introduce more attenuation (need more amplifies or repeaters)

 Most common medium  Telephone network -Between house and local exchange (subscriber loop)  Within buildings -To private branch exchange (PBX)  For local area networks (LAN) -10Mbps or 100Mbps

 Analog -Amplifiers every 5km to 6km  Digital -Use either analog or digital signals -repeater every 2km or 3km  Limited distance  Limited bandwidth up to1MHz  Limited data rate up to1Gbps  Susceptible to interference and noise

 Coupling of signal from one pair to another  Coupling takes place when transmit signal entering the link couples back to receiving pair  i.e. near transmitted signal is picked up by near receiving pair

Shielded Twisted Pair (STP) Metal braid or sheathing that reduces interference More expensive Harder to handle (thick, heavy)

 (^) Cat 3 -up to 16MHz -Voice grade found in most offices -Twist length of 7.5 cm to 10 cm  (^) Cat 4 -up to 20 MHz  Cat 5 -up to 100MHz -Commonly pre-installed in new office buildings -Twist length 0.6 cm to 0.85 cm  (^) Cat 5E (Enhanced ) -4 pairs per cable

• high care taken in design and manufacturing

 Most versatile medium  Television distribution -Cable TV  Long distance telephone transmission -Can carry 10,000 voice calls simultaneously -Being replaced by fiber optic  Short distance computer systems links  Local area networks

THANKYOU