Transmission Media - Vimal 10b

7/30/2019 Transmission Media - Vimal 10b

1/12


2/12

A transmission medium is a materialsubstance thatcan propagate energy waves.

The term transmission medium also refers toa technical device that employs thematerial substance to transmit or guidewaves. Thus, an optical fiber or a coppercable is a transmission medium. Not only

this but also is able to guide thetransmission of networks.Transmission media can be divided into wired

and wireless media.


3/12

Data is transmitted through wires or cables.

There are 3 types of cables for wired media

:1) Twisted Pair Cable

2) Coaxial Cable

3) Optical Fibre Cable


4/12

Commonly used in telephones and computernetworking. It consists of four twisted pairs ofcolour coded cables which are

1) Green and white2) Orange and white

3) Blue and white

4) Brown and white.

This cable can be further divided into 2categories:

1) Shielded TP

2) Unshielded TP


5/12

The wires are first wrapped with an insulatedcovering and then all the shielded pair arethen covered by an outer covering providingmore insulation/immunity. They are more

expensive than UTP, not easy to Install but havebetter immunity. They are shielded to preventelectromagnetic interference as the shielding isusually made of metal. Shielded TP wires has aspecial grounding wire known as Drain wire.


6/12

Unshielded TP have no shielding. They are notexpensive, flexible by nature thus easy to install, butcant carry data over long distance.

UTP cables are found in many Ethernet networks andtelephone systems. For indoor telephone

applications, UTP is often grouped into sets of 25 pairsaccording to a standard 25-pair color code. Alsocommonly used in computer networking. Primarilyused for security cameras.


7/12

Coaxial cable consists of a central

conducting axis wrapped inside an

insulated layer. Then it is surrounded by wire

mesh through conduction for groundingand lastly, it is encased with a covering.

It is commonly used as cables for TVs and

data communications


8/12

Fibre optics cables are the fastest and most efficientcables now a days but are very costly. It is made from thefact that light travel faster through glass as compared toelectrical signals in traditional wires. Fibre Optics cablesconsists of very thin strands of glass that is as thick as asingle strand of human hair and data is transmittedthrough this glasses as light signals.

Since this wires are made out of glass, they are also veryfragile and costly and requires trained professionals tohandle them.

They are now used in modems and routers for fasterinternet.


9/12

There are 3 kinds of wireless media:1) Bluetooth

2) Infrared

3) Microwave

Wireless transmission media enables computers to send data using radio waves orinfrared light. Infrared is a wireless transmission medium that sends signals using infraredlight waves. Broadcast radio is a wireless transmission medium that distributes radio

signals through the air over long distances such as between cities, regions, andcountries, and short distances such as within an office or home. Cellular radio is a formof broadcast radio that is used widely for mobile communications, specifically wirelessmodems and cellular phones. Microwaves are radio waves that provide a high-speedsignal transmission. A communications satellite is a space that receives microwavesignals from an earth-based station, amplifies the signals, and broadcasts the signalsback over a wide area to any number of earth-based stations.

Advantages

It is convenient It is very versatile in that you can easily move from place to place with no restraints

It usually runs a little faster than a standard connection

DisadvantagesIt is a little bit more expensive to change a regular connection to a wireless one

It is easier to hack into a wireless network than a standard connection


10/12

Infrared is a wireless transmission medium that sends signalsusing infrared light waves. Infrared is used in devices such asthe mouse, wireless keyboard and printers. Somemanufacturers provide a special port called the IrDA port

that allows a wireless keyboard to communicate with a PC.Infrared signals have frequencies between 300 GHz to 400 THz

To communicate, infrared devices often must be withinabout 5 meters (15 feet).


11/12

Bluetooth technology uses short-range radio waves totransmit data between two Bluetooth devices The datatransfers between devices at a rate of 1Mbps

To communicate, Bluetooth devices often must be withinabout 10 meters (33 feet)


12/12

Microwave transmission refers to the technology of transmittinginformation or energy by the use of radio waves whose wavelengths areconveniently measured in small numbers of centimetre; these arecalled microwaves. This part of the radio spectrum rangesacross frequencies of roughly 1.0 gigahertz (GHz) to 30 GHz. Thesecorrespond to wavelengths from 30 centimeters down to 1.0 cm.

Microwaves are widely used for point-to-point communications becausetheir small wavelength allows conveniently-sized antennas to directthem in narrow beams, which can be pointed directly at the receivingantenna. This allows nearby microwave equipment to use the samefrequencies without interfering with each other, as lower frequencyradio waves do. Another advantage is that the high frequency ofmicrowaves gives the microwave band a very large information-

carrying capacity; the microwave band has a bandwidth 30 times thatof all the rest of the radio spectrum below it. A disadvantage is thatmicrowaves are limited to line of sight propagation; they cannot passaround hills or mountains as lower frequency radio waves can.

Transmission Media - Vimal 10b

Documents

Transcript of Transmission Media - Vimal 10b