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.