presentation on transmission medium.ppt

7/27/2019 Presentation on Transmission Medium.ppt

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Presentation on TransmissionMedium

Presented by:

Pooja Relan (40)

Ajinkya Sanap (41)

Anish Sanghvi (42)



Transmission Medium

On any network, the various entities mustcommunicate through some form of media.

Just as humans can communicate through

telephone wires or sound waves in the air,computers can communicate through cables,light, and radio waves.

Transmission media enables computers to sendand receive messages



Types of Transmission Medium

There are two main groups oftransmission media, namelythe guided medium and thewireless medium/ unguidedmedium.

For the guided medium, thereis a physical path (such as acable) for electromagneticwave propagation.

For the wireless medium,

however, the electromagneticwave is transmitted throughair, water, or vacuum.



Twisted Pair Cable

A twisted pair consists of twoconductors (normally copper),each with its own plasticinsulation, twisted together.

Low frequency transmission

medium

We can transmit 1 Mbps overshort distances (less than100m).

They are mainly used to

transmit analog signals, butthey can be used for digitalsignals.

Types of Twisted Pair Cable:

- UTP (Unshielded Twisted-Pair)

- STP (Shielded Twisted-Pair)



Advantages & Disadvantages

Advantages:

- Inexpensive and readily available

- Flexible and light weight

- Easy to work with and install Disadvantages:

- Susceptibility to interference and noise

- Attenuation problem

For analog, repeaters needed every 5-6km For digital, repeaters needed every 2-3km

- Relatively low bandwidth (3000Hz)



Applications

Twisted-pair cables are used in

telephone lines to provide voice

and data channels.

The DSL lines that are used by

the telephone companies to provide high data-rate

connections also use the high-

bandwidth capability of

unshielded twisted-pair cables.

Local-area networks, such as

10Base-T and 100Base-T, also

use twisted-pair cables.



Coaxial Cable

Coaxial cable (or coax)carries signals of higherfrequency ranges thanthose in twisted- pair

cable. Coaxial consists of a core

made of solid coppersurrounded by insulation,a braided metalshielding, and an outercover.




Advantages:

- Higher bandwidth

400 to 600Mhz

up to 10,800 voice conversations- Much less susceptible to interference thantwisted pair

Disadvantages:

- More expensive than twisted pair cable.- Harder to work with & gets easily damaged.



Applications

Television distribution

Ariel to TV

Cable TV

Long distance telephonetransmission

Short distance computersystems links

Local area networks



Fiber Optic Cable

Relatively new transmissionmedium used by telephonecompanies in place of long-distance trunk lines

Require a light source withinjection laser diode (ILD)or light-emitting diodes(LED)

Optical fiber consists of a

glass core, surrounded by aglass cladding with slightlylower refractive index.



Fiber Optic Transmission Modes

Single-mode fiber

Carries light pulsesalong single path.

Multimode fiber

Many pulses of lighttravel at differentangles




Advantages:

- Greater capacity (bandwidth of up to 2 Gbps).

- Smaller size and lighter weight.

- Lower attenuation.- Immunity to environmental interference.

- Highly secure due to tap difficulty and lack of signalradiation.

Disadvantages:- Expensive over short distance

- Requires highly skilled installers

- Adding additional nodes is difficult



Applications

The fiber optic cable isoften found in backbonenetworks because itsbandwidth is cost

effective. Used in TV companies.

LAN such as 100 Base-FX Network



Unguided Transmission Medium

Unguided media – nomedium to control orcontain signals;therefore, no boundaries

transmission andreception are achieved bymeans of an antenna.

Types of unguided media

systems: Microwave

Satellite

Radio



Types of Unguided Transmission Medium

Radio Wireless transmission of electrical waves over air Each device has a radio transceiver with a specific

frequency Low power transmitters (few miles range) Often attached to portables (Laptops, PDAs,

cell phones)



Infrared

“invisible” light waves (frequency is below redlight)

Requires line of sight; generally subject tointerference from heavy rain, smog, and fog

Used in remote control units (e.g., TV) Microwave Transmission

High frequency form of radio communication. Antenna at transmitter & receiver must be

aligned (Line of Sight).

Does not penetrate through objects.




Advantages:

- easy to install - no need to run cablesthroughout the building

- users are able to move around with portable

systems and stay connected

- transmission speeds are very high

Disadvantages:

- less secure - its lot easier to hack into a

wireless network.



Applications

They are used in Cellular phones.

They are used in wireless LANs.

AM and FM Radio, television, maritime radio,

cordless phone, and paging are examples ofmulticasting.

Infrared waves are used in communicationbetween devices such as Keyboard, PCs andPrinters.



THANK YOU

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