Module 2
Data Communication
Fundamentals
Lesson 2
Transmission Media
Specific Instructional ObjectivesSpecific Instructional Objectives
At the end of this lesson the students will be able to:
Classify various Transmission Media
Distinguish between guided and unguided media
Explain the characteristics of the popular guided transmission media:
Twisted-pair
Coaxial cable
Optical fiber
Transmission MediaTransmission Media
physical path between transmitter and receiver in a data transmission system
Classes of Transmission MediaClasses of Transmission Media
Guided Media - Guided Media - Twisted PairsTwisted Pairs
two wires typically ``twisted'' together in a helix
carry both analog and digital signals
Data rates of several Mbps
Spans distances of several kilometers (100m for LAN)
Guided Media - Base band CoaxialGuided Media - Base band Coaxial
simply, Coax cable
There are two common ways to connect to a coaxial cable:
vampire taps
T-junction
Guided Media – Fiber Optic CableGuided Media – Fiber Optic Cable
consists of a hair-width strand of silicon or glass, and the signal consists of pulses of light
Unguided Media – Infrared LightUnguided Media – Infrared Light
A short range “line of sight” media using infrared light
Commonly used in small personal devices
Unguided Media - MicrowaveUnguided Media - Microwave
a short electromagnetic wave (longer than infrared but shorter than radio waves);
used for radar and microwave ovens and for transmitting telephone, facsimile, video and data
Unguided Media – Satellite Unguided Media – Satellite CommunicationCommunication
Satellite communication is based on ideas similar to those used for line-of-sight.
A communication satellite is essentially a big microwave repeater or relay station in the sky.