A SUMMER INDUSTRIAL TRAINING PRESENTATION ON SIGNALLING & TELECOMMUNICATION TAKEN AT NORTH WEST RAILWAY -JAIPUR

Contents Introduction to Indian Railways Introduction to Optical Fibers Fiber Optic Communication Optical Fiber Construction Modes of Optical Fiber Working of OFC Advantages & Disadvantages of Optical Fibers. Application of OFC in Railways Microwave Communication Application of Microwave in Railways Conclusion Reference

Introduction to Indian Railways  Indian Railway is a department owned and controlled by the Govt.of India, via the Ministry of Railways.  Indian railway is divided into zones, which are further divided into divisions.  Jaipur is the zonal headquarter of the North Western Railway zone  The formal inauguration ceremony of IR was performed on 16th April 1853 with the first passenger train steamed out of Howrah station destined for Hooghly, a distance of 36 km.

Optical Fiber  An optical fiber ( or fiber ) is a glass or plastic fiber that carries light along it’s length.  It has two main component layers: a) Core & b) Cladding.  Light is kept in the “core” of optical fiber.  Cladding is for the protection of fiber.

Fiber Optic Communication  In this technique electric signal is converted into light waves by using LASER DIODE or LED.  The light forms an electromagnetic carrier wave that is modulated to carry information.  The light enters from one end of optical fiber and through multiple reflections it reaches to the other end.

Total Internal Reflection

Optical Fiber Construction  Core: Thin Glass Center of the fiber where light travels.  Cladding: Outer Optical Material surrounding the Core.  Buffer Coating: Plastic Coating that protects the Fiber.

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 jacketglass or plastic cladding fiber core

Index Profile  The boundary between the core and cladding may either be abrupt, in step-index fiber or gradual, in graded-index fiber  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.  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.

Fiber Optic Cable  Single-mode Fiber: Carries light pulses along single path.  Multi-mode Fiber: Many pulses of light Generated by LED At different angles. Types:-

Mode of Fibers 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 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.

Working Of OFC

Advantages of Optical fiber.  Thinner than other tubes.  High Carrying Capacity.  Provides a very large Bandwidth  Less signal distortion  Non-inflammable  Light Weight

Fiber Optic Disadvantages.  Expensive over short distance  Very high Installation charges & demands high skills.  Adding additional nodes is difficult.

Use of OFC in Railways.  To optimize train scheduling.  Traffic light monitoring.  For linking of telephone exchanges.  Control communication.  Signaling application for safe transmission.  In data transmission circuits.

Microwave Communication  The international telecommunications system relies on microwave and satellite links for long- distance international calls.  Microwaves are electromagnetic waves whose frequencies range from 3 GHz to 300 GHz.  There are large number of bands in microwave region.  Microwave communication is known as a form of "line of sight" communication, because there must be nothing obstructing the transmission of data between these towers for signals to be properly sent and received.

 The voice, video, or data channels are combined by a technique known as multiplexing to produce a BB signal.  This signal is frequency modulated to an IF and then up converted (heterodyned) to the RF for transmission through the atmosphere.  The reverse process occurs at the receiver. The microwave transmission frequencies are within the approximate range 2 to 24 GHz. Microwave Transmitter and Receiver

Block Diagram Of Microwave Center

 Controlling of trains.  To give correct running and stopping information of the trains.  It help the railway staff to communicate for this purpose.  Stations on average of 40 km can communicate with each other by microwave. Application Of Microwave In Indian Railways

I also captured the knowledge about the controlling of typical railway network proceed between many junction station. I have gained the knowledge of the microwave communication used in railway. Conclusion I feel I got the maximum out of that experience. Also I learnt the way of work in an organization, the importance of being punctual, the importance of maximum commitment, and the importance of team spirit

Reference