TRANSMISSION MEDIA

Department of CE/IT

Introduction

Data is transmitted form one place to another using some

transmission media.

The transmission medium is the physical path between

transmitter and receiver for the data communications

signal energy.

It is known by several alternative names such as

transmission path, line, channel, trunk, link, circuit, et.

The medium can be wire, air or vacuum, or optical fiber.Department of CE/IT

Characteristics of Transmission media

DistanceBandwidthAttenuationResistance SecurityCastlinkage

Department of CE/IT

Types

Transmission media can be broadly categorized into two

types

Guided Transmission Media

Unguided Transmission Media

Department of CE/IT

GUIDED MEDIA

Department of CE/IT

Guided media

Guided transmission media uses a ”cabling” system that guides

the data signals along a specific path.

The data signals are bound by the “cabling” system.

Guided Media is also known as Bound Media.

The three guided transmission media are as follows:

Twisted Pair Cable

Coaxial Cable

Optical fiber

Department of CE/IT

Twisted Pair Cable

Twisted-pair cable is a type of cabling that is used for

telephone communications and most modern Ethernet

networks. A pair of wires forms a circuit that can transmit data.

The pairs are twisted to provide protection against crosstalk,

the noise generated by adjacent pairs.

Two basic types of twisted-pair cable exist:

unshielded twisted pair (UTP)

Shielded twisted pair (STP).

Department of CE/IT

Twisted Pair Cable

Department of CE/IT

Types

Department of CE/IT

Common use

Voice Telephony (including private branch exchanges)

Digital Subscriber Line (DSL) in many flavors

Department of CE/IT

Co-axial Cable

Coaxial Cable consists of 2 conductors.

The inner conductor is held inside an insulator with the other

conductor woven around it providing a shield.

An insulating protective coating called a jacket covers the

outer conductor. The outer shield protects the inner conductor

from outside electrical signals.

The distance between the outer conductor (shield) and inner

conductor plus the type of material used for insulating the

inner conductor determine the cable properties or impedance. Department of CE/IT

Co-axial Cable

Department of CE/IT

Common Uses:

Cable TV (Old: RG-59; New: RG-6)

Ethernet (RG-58: 10Base2; RG-8: 10Base5)

Amateur radio

Department of CE/IT

Fiber optic Cable

Description:

A thin glass core surrounded by cladding that reflects

light into the core, surrounded by a protective

plastic buffer/jacket.

Example:

Department of CE/IT

UNGUIDED MEDIA

Department of CE/IT

Introduction

Unguided media relates to data transmission through the

air and is commonly referred to as wireless. The

transmission and reception of data is carried out using

antenna.

These media can carry such electromagnetic signals as

microwave, infrared light waves, and radio waves.

Department of CE/IT

Unguided Media

Department of CE/IT

Types

Directional (in a beam)

Omnidirectional (all around)

Department of CE/IT

Laser

Unidirectional

High bandwidth

Cannot penetrate thick fog or rain

(Doesn't require an FCC license)

Department of CE/IT

Infrared

Mostly directional

Cheap

Do not pass through solid objects (so no license is required)

Department of CE/IT

The End

Department of CE/IT