07-11-2012, 01:26 PM
Transmission Media
1Transmission Media.ppt (Size: 300.5 KB / Downloads: 238)
Overview
Guided transmission media – wire (twisted pair, cable, fiber)
Unguided – wireless (radio wave, microwave, satellite)
Characteristics and quality determined by medium and signal
For guided, the medium is more important
For unguided, the bandwidth produced by the antenna is more important
Key concerns are data rate and distance
Design Factors
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)
Twisted Pair - Applications
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
Near End Crosstalk
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
Satellite Microwave
Satellite is relay station
Satellite receives on one frequency, amplifies or repeats signal and transmits on another frequency
Requires geo-stationary orbit
Height of 35,784km
Television
Long distance telephone
Private business networks
1Transmission Media.ppt (Size: 300.5 KB / Downloads: 238)
Overview
Guided transmission media – wire (twisted pair, cable, fiber)
Unguided – wireless (radio wave, microwave, satellite)
Characteristics and quality determined by medium and signal
For guided, the medium is more important
For unguided, the bandwidth produced by the antenna is more important
Key concerns are data rate and distance
Design Factors
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)
Twisted Pair - Applications
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
Near End Crosstalk
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
Satellite Microwave
Satellite is relay station
Satellite receives on one frequency, amplifies or repeats signal and transmits on another frequency
Requires geo-stationary orbit
Height of 35,784km
Television
Long distance telephone
Private business networks