Presentation By:Tarun Kumar MatriayaEC-B VII SEMRoll No: 0700131202

Industrial Training Seminar

Outline

Summer Training at North Central Railways, Allahabad from 30th June, 2009 to 30th July, 2009.An amazing experience as I got to see, How exactly the communication system works for Indian Railways.Main Objective was to learn Optical Fibre Communication In Railways.

Contents

Introduction to Indian RailwaysIntroduction to Optical Fibres.Advantages of Optical Fibres.Disadvantages of Optical Fibres.Application of Optical Fibres.Types Of Optical Fibres.Optical Fibre CommunicationWorking of OFC.Use Of OFC in Railways.

Introduction to Indian Railways

1832: The first proposal was introduced for having Railways In India.1853: On April 16th, at 3:35 pm, The first train left from Bombay to Thane.

November 1947 : John Mathai (not formerly designated as Minister to Railways) presents the first Railways budget for Independent India.

Present Railway Minister: Dinesh Trivedi.

Optical Fibre

An optical fibre ( or fiber ) is a glass or plastic fibre that carries light along it’s length.

It has two main component layers: A Core & A Cladding.

Light is kept in th “core” of optical fibre.

Cladding is for the protection of fibre.

Advantages of Optical fibre.

Thinner than other tubes.Less expensiveHigh Carrying Capacity.Provides a very large BandwidthLess signal distortionNon- flammableLight Weight

Fibre Optic Disadvantages.Expensive over short distance.Very high Installation charges

& demands high skills.Adding additional nodes is

difficult.

Areas Of Application

TelecommunicationLocal Area NetworksCable TVCCTVOptical Fibre Sensors

Optical Fibre Construction

Core: Thin Glass Center of the fibre where light travels.

Cladding: Outer OpticalMaterial surrounding theCore.

Buffer Coating: PlasticCoating that protects theFibre.

Material Used.

The “Core” , & the lower refractive index “Cladding” , are typically made of high quality silica glass, though they can be both made of plastic as well.

Fiber Optic Layers.

Consists of three concentric sections.

plastic jacket glass or plasticcladding fiber core

Mode Of Propagation

Two main categories that are used in Fibre

Optic Communications are:

Multi-mode Optical Fibre

Single Mode Optical Fibre

Fibre Optic Cable

Single-mode Fibre:Carries light pulsesalong single path.

Multi-mode Fibre:Many pulses of lightGenerated by LEDAt different angles.

Single Mode Fibres

Single-mode fibers – used to transmit one signal

per fiber (used in telephone and cable TV). They

have small cores(9 microns in diameter) and

transmit infra-red light from laser.

Multi-mode Fibres

Multi-mode fibers – used to transmit

many signals per fiber (used in

computer networks). They have larger

cores(62.5 microns in diameter) and

transmit infra-red light from LED.

Index Profile

The boundary

between the core

and cladding may

either be abrupt, in

step-index fiber, or

gradual, in

graded-index fiber.

Step-Index

A step-index fiber has a central core with a

uniform refractive index. An outside

cladding that also has a uniform refractive

index surrounds the core;

However, the refractive index of the

cladding is less than that of the central core.

Graded-Index

In graded-index fiber, the index of

refraction in the core decreases

continuously between the axis and the

cladding. This causes light rays to bend

smoothly as they approach the cladding,

rather than reflecting abruptly from the

core-cladding boundary.

Optical Fiber Communication

Fiber Optic Communication

It is a method of transmitting information

from one place to another by sending

light through an optical fiber.

The light forms an electromagnetic

carrier wave that is modulated to carry

information.

Block Diagram of OFC

Total Internal Reflection

Use of OFC in Railways.

To optimize train scheduling.Speed measurement.Signal distribution by FBG.Traffic light monitoring.