Transmission media presentation

Prepared By : Saba Ansari

“TRANSMISSION MEDIA”


Transmission Media. Characteristics of Transmission Media and its type. Limitations and advantages. Primary cause of signal loss.

TOPICS COVERED


WHAT IS TRANSMISSION MEDIA

Sending of data from one device to another is called transmission of data.

Medium used to transfer data is called ‘media’.

Transmission of data from medium is called transmission media.


TYPES OF TRANSMISSION MEDIA


TYPES OF TRANSMISSION MEDIA

Guided Media◦ Coaxial cable◦ Twisted pair cable

Shielded Twisted Pair (STP) Unshielded Twisted Pair (UTP)

◦ Optical fiberUnguided Media

◦ Microwave◦ Radio transmission◦ Satellite


GUIDED (WIRED)

Guided media is the media in which the data signals/information flows through some bounded media such as wire, cables etc.

The media itself is very important in determining the limitations of transmission.


COAXIAL CABLE

Coaxial cable consists the following layers in its construction◦ The copper conductor ◦ Insulation of plastic foam◦ Second conductor or shield of mesh tube or metallic foil◦ Outer jacket of tough plastic

Coaxial cable can be used over longer distances.


COAXIAL CABLE-CHARACTERISTICS

It is comparatively inexpensive Its installation is comparatively simple It must be grounded properly in a network connection


TWISTED PAIR

A twisted pair consists of two insulated copper wires arranged in a regular spiral pattern

The twisting tends to decrease the crosstalk interference between the adjacent pairs in a cable

Twisted pair may be used to transmit both analog and digital transmission

Twisted pair is limited in distance, bandwidth and data rate


TWISTED PAIR

Unshielded Twisted Pair (UTP) Shielded Twisted Pair (STP)

• Ordinary telephone wire • Cheapest• Easiest to install

• Metal braid or sheathing that reduces the interference

• More expensive, harder to handle (thick , heavy)


FIBER OPTICS

Fiber optic cable is known as most sophisticated cables used in long distance network communications

It has inner core of glass that conducts light. This inner core is surrounded by cladding

Cladding is nothing but the layer of glass material that reflects the light back in to the core

Each fiber is then surrounded by plastic sheath

plastic jacket glass or plasticcladding fiber core


Use total internal reflection to transmit light

Can use several different light sources ; LED (Light Emitting Diode), ILD (Injection Laser Diode).

FIBER OPTIC -CHARACTERISTICS


GUIDED TRANSMISSION MEDIA-ADVANTAGES AND DISADVANTAGES

MEDIA ADVANTAGES DISADVANTAGES

COAXIAL CABLE • Inexpensive • Easy to expand• Widely used

• Single cable failure can take down an entire network

• Limited in distance

TWISTED PAIR • Easy installation• Capable of high

speed for LAN • Low cost

• More difficult installation

FIBER OPTICS • Fast speed• Can go long

distance

• Very costly• Hard to install • Bending is not

easy


Send communications signals through air or space.

Used when inconvenient or impossible to install cables.

UNGUIDED MEDIA-WIRELESS MEDIA


Earth-based reflective dish that contains antenna, transceivers, and other equipment necessary for microwave communications

Uses line-of-sight transmission

◦Must transmit in straight line with no obstructions between microwave antennas

MICROWAVE


Microwave transmission covers a substantial portion of the electromagnetic spectrum.

Common frequencies used for transmission are in the range 1 to 40 GHz.

The higher the frequency used, the higher the potential bandwidth and therefore the higher the potential data rate.

MICROWAVE-CHARACTERISTICS


Form of broadcast radio used widely for mobile communications.

RADIO TRANSMISSION

• Some use radio frequencies to connect the workstations together, some use infrared technology.


The range 30 MHz to 1 GHz is an effective one for broadcast communications.

A prime source of impairment for broadcast radio waves is multipath interference.

RADIO TRANSMISSION-CHARACTERISTICS


Satellites are transponders (units that receive on one frequency and retransmit on another) that are set in geostationary orbits directly over the equator. These geostationary orbits are 36,000 km from the Earth’s surface

SATELLITE


Optimum frequency range for satellite communication is 1 to 10 GHz.

The most important property is the long communication delay for the round trip (about 270 ms) because of the long distance (about 72,000 km) the signal has to travel between two earth stations.

This poses a number of problems, which are to be tackled for successful and reliable communication.

SATELLITE-CHARACTERISTICS


UNGUIDED TRANSMISSION MEDIA-ADVANTAGES AND DISADVANTAGES

MEDIUM ADVANTAGES DISADVANTAGES

MICROWAVE • Point-to-Point communication in line-of-sight.

• Can be done quickly at lower cost.

• Must have visual contact between the antennas

SATELLITES • Can be at high, medium, or low orbit used in GPS

• Expensive to build and maintain

RADI O TRANSMISSIONS

• Inexpensive and easy to install

• Effective for short ranges , used in LANs

• Limited range ,• difficult to secure

Free space loss is the primary source of signal loss in satellites.

As the signal propagates through the atmosphere it disperses with normal terrestrial antennas, the distance is so short that is rarely an issue.

However the great distance that satellites must communicate over make this a major problem for

global space-based communication.

PRIMARY CAUSE OF SIGNAL LOSS


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Transmission media presentation