CommunicationChannelAnd its types

Presenter: Zainab Lali

What is Communication Channel ?

• Transfers data or

information from one place

to another

• Also known as Transmission

Media

Channel

Sender

Receiver

Reasons For Transmission Impairence

• Attenuation

• Distortion during signal propagation

• Noises

TYPES OF TRANSMISSION MEDIA

TransmissionMedia

GUIDED MEDIA

UNGUIDEDMEDIA

GUIDED MEDIA

Twisted Pair

Cable Coaxial

Cable

Fiber Optic Cable

Twisted Pair Cable

• Consisting of pairs of

twisted copper wires.

• Can transmit 1 Mbps over

short distances (less than

100m).

• Mainly used to transmit

analog signals.

APPLICATIONS

• They are used in telephone lines to provide voice and data channels.

• Local area networks

COAXIAL PAIR CABLE

Coaxial consists of :

A core made of solid copper,

Surrounded by insulation,

A braided metal shielding,

And an outer cover.

CHARACTERS

Bandwidth:

80 times greater than that of twisted pair cables

Speed:

Data transmission speed is 10Mbps.

BENEFITS Most versatile medium

Television distribution

Long distance telephone transmission

Can carry 10,000 voice calls simultaneously

Short distance computer systems links

Local area networks

Fiber-Optic Cable

• Uses reflection to guide

light through a channel

• Core is of glass or plastic

surrounded by Cladding

• Cladding is of less dense

glass or plastic

Transmission in Fiber-Optic Cable

Transmission Speed: Upto billion bits per second

APPLICATIONS & BENEFITS

Greater capacity:

Data rates of hundreds of Gbps

Smaller size & weight

Lower attenuation

  Frequency Range

Typical Attenuation

Typical Delay Repeater Spacing

Twisted pair (with loading)

0 to 3.5 kHz 0.2 dB/km @ 1 kHz

50 µs/km 2 km

Twisted pairs (multi-pair cables)

0 to 1 MHz 0.7 dB/km @ 1 kHz

5 µs/km 2 km

Coaxial cable 0 to 500 MHz 7 dB/km @ 10 MHz

4 µs/km 1 to 9 km

Optical fiber 186 to 370 THz

0.2 to 0.5 dB/km

5 µs/km 40 km

COMPARISON

Microwaves

Satellites

Radiowaves

Infra Red

UNGUIDED MEDIA

PROPAGATION METHODS

MICROWAVES TRANSMISSION

Microwave Relay Stations

Height of 40-50ft

Spaced at least 20-30miles apart

CHARACTERS

• Waves are transmitted via microwave relay stations.

• Micro waves are unidirectional.

• Microwave propagation is line of sight.

• Very high frequency Micro waves can not penetrate walls.

• Data transmission speed is 150 Mbps.

BENEFITS

• Typical uses

Television

Long distance telephone

Private business networks

Global positioning

COMMUNICATION SATELLITES

CHARACTERS

• Signals are transmitted from

Earth stations to Satellites

• Data transmission speed is

upto 1Gbps.

BENEFITS:• Transmits large amount of Data.

• Data transmission speed is Very High.

DISADVANTAGES:• Effected by bad weather.

• Have security problems.

• It is costly.

BROADCAST RADIO

• Used to send signals over long & short distances.

• Transmitter sends messages

• Receiver receives messages

• Transceiver can do both

Example:

• Bluetooth

Transmission Rate: 1Mbps

Cellular Radio

Used for mobile

communications

Infrared

• Line of sight transmission

• Short Range

Example:

• Data transmission among

a computer and wireless

keyboard or mouse

CONCLUSION

Transmission media are essential for

communication system.