Guided Media

GUIDED MEDIAPresented by

Shakhawat AminReg. : 2012331009

Dept : Computer Science and Engineering, SUST

AcknowledgementMrs. Sadia Sultana

Assistant professor, CSE, SUST

Mr. Refat KibriaAssistant professor, CSE, SUST

What is a transmission media ?

Transmission Media is a pathway that carries information from sender to receiver.

Transmission Media are located below Physical layer and directly controlled by physical layer.

ClassificationData is normally transmitted through electrical or electromagnetic signals through transmission medium.

Transmission media can be categorized by whether it uses physical path or not.

GUIDED MEDIAIn a transmission media if electrical or electromagnetic waves are guided along a physical path then it is called Guided media.

Twisted pair Cable

A twisted pair consists of two conductors (normally copper), each with its own plastic insulation, twisted together.

One of the wires is used to carry signals to the receiver, and the other is used only as a ground reference.

Provide protection against crosstalk and interference (noise).

For twisting after receiving the signal remains same.

fig: Unshielded twisted pair cable fig: Shielded twisted pair cable

Coaxial CableCoaxial cable (or coax) carries signals of higher frequency ranges than those in twisted pair cable. Instead of having two wires, coax has a central core conductor of solid or stranded wire.The outer metallic wrapping serves both as a shield against noise and as the second conductor, which completes the circuit.

fig: Coaxial cable

To connect coaxial cable to devices, we need coaxial connectors.

The most common type of connector used today is the Bayone – Neill - Concelman (BNC) connector.

Coaxial CableConnectors

fig: BNC connectors

three popular types of BNC connectors:

i. The BNC connector (used to connect the end of the cable to a device)

ii. The BNC T connector (used in Ethernet network to branch out to a connection to a computer)

iii. The BNC terminator (used to prevent the reflection of the signal)

fig: BNC connectors

Fiber-Optic CableA fiber-optic cable is made of glass or plastic and transmits signals in the form of light.

fig: Optical Fiber Cables

To understand optical fiber, we first need to explore several aspects of the nature of light.

Light travels in a straight line as long as it is moving through a single uniform substance.

If a ray of light traveling through one substance suddenly enters another substance the ray changes direction.

fig: Bending of light ray

Fig: Optical fiber

Optical fibers use reflection to guide light through a channel. A glass or plastic core is surrounded by a cladding of less dense glass or plastic. The difference in density of the two materials must be such that a beam of light moving through the core is reflected off the cladding instead of being refract into it.

Two modes (multimode and single mode) for propagating light along optical channels, each requiring fiber with different physical characteristics.

Multimode can be implemented in two forms: step-index fiber & graded-index.

PROPAGATION MODES

Fig : Propagation modes

fig: Fiber Construction

THE END