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CHAPTER 1

INTRODUCTION TO RAILWAY, NEW DELHI1.1 New Delhi Railways

Delhi Suburban Railway is a suburban rail service operated by Northern Railway for the

National Capital Region. This railway service covers Delhi, along with the adjoining districts

of Faridabad, Ghaziabad and other adjoining places in Haryana and Uttar Pradesh. These

services are mostly run using EMU and MEMU rakes. This also includes passenger trains

and DMU services up to Rewari in Haryana, which is also considered part of the National

Capital Region.

Delhi Ring Railway is part of the Delhi Suburban Railway services. The Ring Railway is a

circular rail network in Delhi, which runs parallel to the Ring Road and was conceived during

the 1982 Asian Games. Started in 1975 to service goods, it later upgraded for the Games, when

24 additional services were started. Its circular route is 35 km long, which the train takes 90–120

minutes to complete, both clockwise and anti-clockwise, via Hazrat Nizamuddin Railway

Station, from 8am-7pm. With a return ticket for the entire journey costing 12, compared to with

Delhi Metro, which is around 60, it is preferred by poor and middle-class families. It runs seven

clockwise and six anti-clockwise trains at a peak frequency of 60-90 min., during the morning

and evening rush hours. However in the coming decades Delhi spread far beyond Ring Road,

making the ring railway largely redundant. Nevertheless, prior to the 2010 Commonwealth

Games, 7 stations near the sports venues, namely Chanakyapuri, Sarojini Nagar, Inderpuri Halt,

Lajpat Nagar, Sewa Nagar, Lodhi Colony and Safdarjung, received a facelift at the cost of 3

crores.

Delhi Ring Rail

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The ring-railway service was introduced on a track laid in the 1975 so that the large number of

goods trains originating, terminating, or passing through the city, could bypass the main

passenger stations at New Delhi, Old Delhi and Hazrat Nizamuddin. The track was called the

'Delhi Avoiding Line'. Today, however, the Northern Railway’s service for passengers within the

city has become something which Delhiites are avoiding. There are 12 electric trains on the ring

rail. Only three of the twelve EMUs run to full capacity. The rest have just 1-2% occupancy. The

ring railway starts and ends at the Hazrat Nizamuddin Railway Station with trains running in

both clockwise and anti-clockwise directions around the city.

Delhi Railway division

There are mainly 7 divisions in Delhi railway:

Bhatinda

Rewari

Saharanpur

Palwal

Ambala

Shamli

Delhi Area

1.2 Divisional Railway Manager, New DelhiThe Divisional Railway Manager (DRM) heads the organisation at the division level. There are

currently 67 divisions on the system nationwide. The divisions are primarily involved with train

running but may have loco sheds (repair shops for locomotives), coaching depots (repair home

bases for passenger trains) and wagon depots (repair and maintenance points for freight stock).

Each division has all the functional (both line and staff) organisations. The heads of these

functional groups report to the DRM for administrative purposes but rely on guidance from the

railway board and the zonal headquarters for policy guidelines

1.3 AIMSOur country has a tremendous scope for continuous growth in the field of Railway transportation

that too with the positive competition with road transportation. Hence technology up-gradation,

improved productivity, enhanced safety etc. are the keys to take over the challenge of growth in

the true spirit. The training is the only mode which can prepare the newly inducted railway

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supervisors for making them a positive asset to the organization. More over the refresher courses

are meant for updating the knowledge of the supervisors representing the middle management as

per the latest technical instructions from R.D.S.O. and Railway Board from time to time. The

supervisors can even have an idea that why and on what ground the instructions have been issued

to enable them to implement the same in the field in the best of its sprit. Further the field units

are having their own needs for imparting training in various fields like Welding Technology,

Supervisors Development Program, Computer know how, Internal Audit Course plan for ISO as

well as pre-selection training of the reserved candidates appearing in

LDCE examination.

1.4 Need For TrainingTraining is an investment and not expenditure: A trained man is an asset. The need of training

has become more essential with the development of Electric locomotive, Diesel locomotives,

Super-Fast Trains, Introduction of rolling stocks with Air brake system etc. Training is always

carried out for a purpose. It is the means of maintenance and improving the level of performance

of a trainee by systematically increasing the ability and aptitude of the trainee by giving him

planned tasks, coupled with continuous appraisal, advice and counseling. Growing transportation

needs of our country, productivity of manpower employed, modern technologies, knowledge of

safety knowledge of our production system and Railway Organization Present Status of Railways

are all correlated terms, which need a proper and serially organized and systematized training.

Such training can only be imparted if we have a plan for this.

1.5 ObjectivesThe following are the main objectives of DRM:-

To impart induction training to newly recruited supervisor from RRBs.

To impart training to the candidates inducted as supervisors on the basis of departmental

examination.

To conduct courses as per need of the divisions and workshops like supervisor

development courses, courses of contract management, courses on stores procurement,

courses on computer, pre-selection courses for the reserved candidates.

To conduct refresher courses for the posted supervisors to update their knowledge on the

basis of recent technological developments induced in the system.

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1.6 Labs

So to manage all information of various labs and trainees Computerized System is required

which keeps all records of labs and faculties, trainees.

1. UTS and PRS at Railway station

2. Railnet

3. Control office

4. Exchange

5. TELE

6. PAE

CHAPTER 2

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PRS & UTS NETWORK2.1 IntroductionWith the implementation of computerized passenger reservation system on Northern Railway in

Year 1985-86 at New Delhi, a modest beginning was made which has completely revolutionized

the process of passenger reservation service on Indian Railways. To begin with the computerized

reservation at Delhi was implemented on small VAX-750 computer with just 30 terminals.

Today It is a matter of great pride and satisfaction that highly complex but successful network of

computerized reservation is available at more than 20 major towns including 4 metros of India,

covering almost 25% of the reservation facility available on IR. PRS is equipped with latest state

of art technology both in the field of computer and data communication systems. As a matter of

policy and due to technical reasons, it was decided to have PRS computers only

at Delhi, Bombay, Madras, Calcutta which cover bulk of reservation volume and to have remote

terminals at other major cities connected to host PRS computers through data

links. Today all PRS hosts are CRIS to network all the computers to provide an integrated

reservation system on IR.

Unreservation Ticketing System (UTS) is like as PRS but it have an external devise which store

ticketing information and upload on server.

2.2 Interconnection of PRS & UTS Servers

2.3 Previous Set Up At PRS/Delhi

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2.4 Concept Application Architecture

2.5 Other aspects of PRS

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(a) Use of satellite data links- The Remote Area Business Messaging Network (RABMN) of

Dot commissioned recently may be tried for linking remote stations where normal BSNL links

may not be available or are unreliable. (E.g. North frontier areas from Calcutta PRS) Direct

terminals or teleprinter interfaces might be used sharing one VSAT link working at 1200 bps,

provided the rental and other maintenance costs do not become prohibitive.

(b) Use of Radio Frequency modems- Trials have been conducted using Radio frequency

modems interfaced to VHF half duplex sets and connecting PRS terminals through this data link.

1200 and 2400 bps speeds have been found to be quite successful on WEBEL make VHF sets.

Extension of 1 or 2 terminals at a radius of 8 to 10 Kms with a reasonable line of sight will be

possible at a cheap cost through these modems.

2.6 Benefits of PRS(a) To the Passengers

Transparency

Universal counters for booking

Instant update of status

Instantaneous enquiry

Reduced waiting time

Reservation available at a number of locations in the country

Customer satisfaction

(b) To the Railways

Increased efficiency

Optimal utilization of berths

Real time availability of Accounting Reports

Planning through MIS reports

Analysis of traffic pattern for better overall planning

Reduction in Revenue losses

Saving on Manpower

Eliminate possibilities of fraud

2.7 Technology used Hardware

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Software

Sybase with Replication

2.8 Future Enhancements

Improvements in the response time in the Dynamic (PNR and Seat availability) enquiries.

Other transport information (Road/Air/Water) for major tourist locations

Dynamic Enquiries in Hindi

Providing dynamic enquiries for 24 hours.

2.9 New challenges Maintenance by remote login by vpn

Regular proactive patch updating

Chapter 3

Railnet – An Overview

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3.1 Introduction:Railnet is the name of the Corporate Wide Information System (CWIS) of Indian Railways. It is

aimed to provide computer connectivity between Railway Board, Zonal Railways, Production

units, RDSO, Centralized Training Institutes, CORE, MTP/Kolkata etc.

3.2 Objectives:Railnet has been established with these objectives in mind:

●Eliminate the need to move paper documents between different documents and

●Change from “Periodic Reporting” to “Information on Demand.”

Railnet will expedite and facilitate quick and efficient automatic status update between Railway

Board and Zonal Railway, as well as between divisions and Zonal Railway. Internet gateways

have been established at Delhi, Mumbai, Chennai, Kolkatta and Secunderabad for access of

Internet through Railnet.

3.3 Railnet General Arrangement:

The general arrangement of the equipment’s used in Railnet is shown in the diagram above. The

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WAN link (or the Railnet link) terminates at the router. The router in turn is connected to the

switch.

All the computers including the server is connected to the switch. Additional hubs/switches may

be connected to this switch so as to extend the Railnet LAN further.

Railnet users can exchange emails on the Internet. Commercial Dept. is extensively using Railnet

for their “Complaint Center.” Railways have launched their web pages and they keep up to date

information in these web pages. A Railnet authorized user can browse the Internet through

Railnet. A Railnet user can share resources with a co-user on Railnet.

3.4 Network Topology:The network in which the terminals are interconnected with each other for inter communication

Within and outside the network is called as Topology. Basically the Topology is categorized in

following four types of designs.

4

(a) Mesh topology-

In mesh topology every device has a dedicated point to point to every other device. Every device

must have (n-1) I/O ports. All WAN is mesh topology.

Advantages are:

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It is robust.

Each link can carry its own data load.

It has privacy or secrecy.

Fault identification is easy5

Mesh disadvantages are larger number of cables & I/O ports are required for each device.

Also the bulk of the wires can be greater than the available space.

(b) Star topology-

In star topology each device has a dedicated point to point link only to central controller called as

HUB as shown. If one device wants to send data to another device, it sends through the HUB.

Advantages are

It is easy to install and reconfigure.

Each device needs only one link. Hence it is less expensive.

If a link fails, only that link has to be attended. All other links remain active.

It is easy to identify fault.

It is also robust.

(c) Bus topology-

A BUS topology is multipoint. One long cable acts as a backbone to link all devices in a

network. The advantage is the installation is easy.

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Disadvantages are

Difficult in fault isolation and reconnection.

Difficult to add device to an exsisting system.

A fault or break in bus cable stops all transmission.

(d) Ring topology-

In a ring topology, each has a dedicated point to point connection only with two devices on either

side of it. A data is passed along the ring in one direction, from device to device until it reaches

its destination. Each device in a ring incorporates a repeater.

The advantages are

It is easy to install & configure.

The disadvantages are unidirectional traffic and a break in the ring can disable entire

network.

To add or delete a device requires only changing two connections.

3.5 Categories of Networks:Networks are categorized in three different categories as

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LAN (Local Area Network)

MAN (Metropolitan Area Network)

WAN (Wide Area Network)

(a) LAN (Local Area Network)-

Local Area Networks (LANs) are networks that connect computers and resources together in a

building or buildings close together. The computers share resources such as hard-drives, printers,

data, CPU power, fax/modem, applications, etc. They usually have distributed processing -

means that there is many desktop computers distributed around the network and that there is no

central processor machine (mainframe).

Location: In a building or individual rooms or floors of buildings or connecting nearby buildings

together like a campus wide network like a college or university.

b.MAN (Metropolitan Area Network)-

Metropolitan Area Networks (MANs) are networks that connect LANs together within a city.

From The Big Picture, we see that telecommunication services provide the connection (storm

clouds) between networks. A local telecommunication service provides the external connection

for joining networks across cities.

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Location: Separate buildings distributed throughout a city. Examples of companies that use

MANs are universities, colleges, grocery chains, gas stations, department stores and banks.

c. WAN (Wide Area Network)-

Wide Area Networks (WAN) are a communication system linking

LANs between cities, countries and continents. The main difference between a MAN and a

WAN is that the WAN uses Long Distance Carriers rather than Local Exchange carriers.

Otherwise the same protocols and equipment are used as a MAN.

Location: City to city, across a country or across a continent. Wide Area Networks (WANs)

connect LANs together between cities or across a country.

3.6 PROTOCOL:

A protocol is a set of rules, which governs how data is sent from one point to another. In data

communications, there are widely accepted protocols for sending data. Both the sender and

receiver must use the same protocol when communicating. One such rule is. ...

BY CONVENTION, THE LEAST SIGNIFICANT BIT IS TRANSMITTED FIRST

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Chapter 4

Exchange4.1 Introduction:C-DOT 128P RAX is a Telephone exchange designed to meet the telecommunication needs of

small sized rural areas. These exchanges are also suitable for Indian Railway applications where

the telephone line capacity is less than 100. Provision is made in the design to expand the line

capacity up to 400 subscribers roughly.

C-DOT (Centre for Development of Telematics) is a Central government organization of India

set up to develop the necessary equipment’s (infrastructure) suitable for Indian climate and

environmental conditions. The system is designed to offer uninterrupted services by using

duplicating methods for control and power supply circuits. Tone generator circuit is also

duplicated.

4.2 Power Supply Unit card:The input voltage is –48+/-4V. The RAX system requires various internal working voltage

sources.

PSU card provides the following output voltages for internal working.

1) +5V-8A – For microprocessor and other digital components.

2) –9V-0.5A – Codec

3) +12V-1A – Relays

4) –5V-0.1A – For other digital components.

5) –48V – For speech

4.3 RAX Control processor (RCP):This card uses 65C02 Micro Processor and has 12K RAM, 48K EPROM & 16K EEPROM

memories. This contains the information pertaining to peripheral cards, metering and other

administrative functions to be performed. Maintenance panel is connected directly to RCP by

which any changes in the data of the exchange can be made (adding, deleting, modifying of

subscriber or trunks etc.).

The main functions RCP are Call processing, Administration and Maintenance.

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Functional Block diagram of RCP card

1. FUNCTIONAL BLOCKS -

a. Processor and Memory.

b. Clock Generation.

c. Address Decoder and Read/Write Generator.

d. Asynchronous Communication and Timer.

e. Error Monitor.

f. EEPROM and Real Time Clock.

g. High Level Data Link Control.

2

4.4 Switching Network (TIC):The TIC/SN is essentially a generic card. It switches voice between the 128 ports, controls

signalling, support diagnostics and duplication under the intelligence of RCP. It can be

understood this way also. The signalling of the termination cards is handled by the signal

processor (SP) and voice by the Switching Network (SN). Both SP and SN are under the control

of Terminal Interface Controller (TIC) which works under instruction from RCP.

1. FUNCTIONS-

1) TIC/SN Switches the PCM (Pulse Code Modulation) digital voice information. This

is to enable the subscribers to converse with each other and to be fed with different

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tones at different stages of the call.

2) TIC (Terminal Interface Controller) derives the identities of the calling and called terminals

and establishes a path through SN (Switching Network) between these terminals. TIC

communicates with RCP on HDLC (High Level Data Link Control) for call related information.

3) Using SPC (Signal Processor Card) it receives status indication for all the 128 port (terminals)

i.e. scan signalling information. This information is passed on to RCP. Also it gets the message

from RCP to drive events on terminals and passes the Drive signalling information to signal

processor. Note: (HDLC) is to ensure that data is transferred quickly and correctly.

4) It keeps on doing periodic diagnostic on the terminal cards including itself and informing RCP

through HDLC messages.23

4.5 Tone generator with Diagnostic card (TGS):Tone Generator card is used to generate call supervisory and test tones for system like PABX

and RAX. It has also capability to diagnosis the tones it produces and thereby can conform sanity

check of the voice path.

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(a) A tone is a simple audio signal having distinct frequency or set of frequencies (usually a

voice frequency i.e. between 20 Hz to 20 KHz).

(b) A tone may be continuous or may have cadence i.e. signal has certain ON – OFF period.

(c) A tone consists of one or more tone components.

(d) A tone component may mean a single frequency signal (400 Hz) or a modulated frequency

signal (400 Hz modulated by 25 Hz) or it can be an addition of two sine waves of different

frequencies as well.

(e) These tone components which contain the PCM samples of a particular frequency or group of

frequencies reside in a bank of memory called tone memory.

(f) Each bank of this tone memory consist s one tone component.

(g) When a tone consists of more than one tone component the second tone component may be

just silence (regarded as inaudible d. c. signal).

(h) If in a tone (like RBT) there is one tone component followed by silence then the tone is said

to have cadence.

4.6 Signal Processor (SP) card:Signal processor exchanges signalling information between Termination cards and Terminal

interface controller. The SP card acts as an interface between the terminal cards and Terminal

interface controller cum Switching Network (TIC / SN) card. This interface is primarily for

supervisory, control and data signal.

1. Main functions-

The Signal processor card performs the following functions:

(a) Receiving supervisory signals such as on - hook / off – hook/ hook switch flash and decadic

(dial) pulses from termination and also for transient validation (noise rejection).

(b) Controlling ringing towards subscriber and providing automatic ring trip when the called

subscriber goes off - hook.

(c) Controlling metering signals.

(d) Recognising incoming ring from incoming junction calls.

(e) Controlling out pulsing towards junction calls.

(f) Channel associated signalling on digital trunks.

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4.7 Subscriber line card (SLC) or line circuit card (LCC):Line circuit card is one of the termination cards and It is the first link in the chain of cards

comprising the exchange.

Line circuit card (LCC) is the direct interface between the exchange and subscriber. Each card

has 8 identical circuits on which it receives 8 pairs of subscriber telephone wires. Each of these

circuits does the following function.

MAIN FUNCTIONS-1. D.C feed to subscriber for signalling and energising handset microphone.

2. Detects the status of the corresponding subscriber telephone handset i.e. on – hook (idle or

ringing) or off – hook (call initialisation or ring trip).

3. Enables the voice of the subscriber to reach a point within the exchange for onward

Transmission to the called party or vice-versa.

4. Through control logic, subscriber line card (SLC) performs a diagnostic check on the basic

health of the card.

5. It has provision to operate from any of the two sets of the input signals i.e. copy – 0 or copy -

1(copy selection).

6. The subscriber line card communicates with the Terminal Interface Controller & Switching

Network (TIC / SN) for voice switching.

7. The subscriber line card communicates with signal processor card (SPC) for Signalling data.

8. Operates Test Access Rely for a particular subscriber line.

The basic function of Line Circuit Card (Termination cards) is collectively termed as BORSCHT

an acronym for –

B - Battery Feed.( -48v, 35 mA)

O - Over Voltage Protection.

R - Ringing.

S - Supervision.

C - Coding & Decoding

H - Hybrid Conversion ( 2 / 4 wire conversion)

T - Testing.

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CHAPTER 5

PUBLIC ADDRESS EQUIPMENT5.1 Typical Small Public Address

5.2 The core of a PA system is the Audio Switching Matrix The matrix routes the input sources (mic, music etc) to output destinations (speaker

zones)

The matrix can also incorporate message cards for alarms or announcements.

All parameters (including microphone controls, signal routing, priority settings and fault

monitoring) are programmable

Activating an input controller makes a request to the matrix. The matrix manages the

request (source/priority/destination) according to the configuration.

5.3 Input Controllers Microphones

Desk, wall or equipment rack mounting

Single or multiple selection buttons

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Single button unit (PTT press to talk)

Control of microphone or audio source such as a CD player

Controllers

Control of audio source such as a CD player

Pre recorded messages within the system

5.4 Microphones Typically comprise

Goose neck or fist microphone

Zone selectors with busy and confirm LED indication

PTT button and speak indicator

Microphone to line level pre amplifier. Microphone signals are too small to be

transmitted over distance. Need to amplify at the microphone.

Audio limiter (boosts quiet voice, reduces loud voice), digital chime and 20KHz

surveillance.

All these elements would be housed within the microphone unit.

5.5 Amplifiers

Grouped together to meet the specific power requirements of each zone.

Efficient use of output power and reduces the mechanical size of the power racks

Protected from short circuit speaker lines.

The amplifiers are protected from being over-driven by thermal cut-out.

5.6 Noise sensing

Typically used in Airports, Exhibition Halls and Convention Centres or where

background noise levels vary

Provides automatic adjustment of system sound pressure

level to compensate for fluctuations in background noise.

Background noise picked up by microphones in the zone Matrix

5.7 Typical Public Address

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Fig

Common Intelligibility Scale (CIS). Unifies the most common intelligibility measures into one

scale

Fig

Speech Transmission Index (STI) still referred to often in Specifications

Fig

5.8 Audio surveillance

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Surveillance tone (20kHz) is injected into the audio path via the microphone pre

amplifier or message card.

This tone follows the same audio path as the microphone signal, through the matrix,

amplifier, speaker lines and back to the surveillance detector at the rack.

If the tone level falls a fault is indicated on the Fault Monitoring Panel on the rack.

The switching matrix receives up to three sources carrying the surveillance tone and has a

number of destination channels requiring surveillance.

5.9 Battery Backup

Voice Alarm Systems require battery Backup to comply with BS 5839 pt 8 or local

standards

Standby battery units provide a self-contained 24V DC supply. Sized to provide the stand

by supply capability required (more kit = more batteries).

Typically 24 hours standby (no calls) followed by 0.5 hour Full Alarm

5.10 Sound Pressure Level (SPL)

Sound pressure level (loudness) measured in decibels (dB).

“Sensitivity” of speaker is a measure of it’s efficiency.

Sensitivity = SPL at a distance of 1 metre with a speaker input level of I watt.

5.11 Loudspeaker selection

1. Cabinet Speakers;

Wall/surface mount

2. Column Speakers

More than one cone speaker mounted in an enclosure

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Typically 4 to 10 cones mounted vertically

Creates very directional beam of sound

Typical applications

Airport check-in halls, sports halls, churches

3. Horn Speakers

Directional beam

Higher sound pressure levels as they are more efficient

Ideal for outdoor and industrial use.

Explosion proof available suitable for hazardous area installation.

The frequency range small therefore not suitable for high

Quality music broadcast (except “music horns”!)

Typical applications

Factories, power stations, car parks

5.12 System example

Warehouse, assembly & picking areas; background music, time alarm calls, fire alarm calls and

general paging Offices; fire alarm and general paging Restaurant;

Reception; Paging microphone, fire alarm and paging

Gatehouses; Paging microphone, fire alarm and paging

Entrance; Fireman’s microphone

CHAPTER 6

TELE COMMUNICATION LAB

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6.1 INTRODUCTION

Signal and Telecommunication Department is responsible for installation and maintenance of

Signaling system essential for the safe & speedy movement of trains and Telecommunication

systems required for the effective utilization of the large fleet of locomotives and other rolling

stock and track as well as for the administration of the vast Railway Network.

Telecommunication is a vital infrastructure for managing any transportation network. Indian

Railway has an in-house Railway Telecommunication Network for managing Train operations

and staff management and to offer Passenger Amenities. In terms of the sophistication in

Signaling and Telecommunication installations, Southern Railway occupies the pride of place

among the various Indian Railway systems. S&T Department consists of both administrative and

project offices with a workshop at Podanur. Organizational setup and duties of officers and other

salient features of the department are detailed below.

SALIENT FEATURES

1.0 SIGNALLING

1.1 Multiple Aspect Colour Light Signalling (MACL)

Mechanical signals of Semaphore type are progressively replaced by Electrical signaling with

Multiple Aspect Colour Signals (MACL). MACL signals have better visibility, quick operation

and less maintenance.

1.2.1 Route Relay Interlocking (RRI) and Central Control Panels in signal control system

By mere operations of knobs and route buttons, routes are set automatically and signals are

cleared with absolute safety. The entire station is track circuited. Points and signals are operated

by individual knobs/slides in small yards.

1.2.2 Panel Interlocking system

Unlike Route relay interlocking, in panel interlocking points and signals are operated

individually. This is being adopted in smaller wayside stations.

1.2.3 Solid State Interlocking

As a technological development, the solid state with electronics system having software

programming, solid-state interlocking signaling control system is being now inducted to achieve

economy and flexibility. This sophisticated microprocessor based interlocking system works

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through Microprocessor devices and software programming. In this system there is less number

of relays, and alterations/additions in the yard is possible without much extra wiring. This system

adopts the usage of latest CENLEC standard of software validation.

1.3 Automatic Block Signalling with Continuous Track Circuiting

Automatic Block signalling systems are mostly used when the train traffic become more

congested and busy, especially in suburban area and to increase line capacity. This eliminates

block working and trains are signalled automatically without much dependence on human

element. This ensures train safety, speed and also detects any rail discontinuity.

1.4 Token less Block working

In the absolute block system in single line, Token Block instruments are used. The token will be

handed over to the driver of train after granting line clear to enter in the Block section. The

process of handing over of token at every station is time consuming and laborious resulting in

token missing. The system of token less block working helps to increase line capacity on single

line sections.

1.5 Audio Frequency Track Circuits (AFTC)

Southern Railway has the distinction of introducing Audio Frequency Track Circuit for the first

time in the Indian Railway system in 1994-95. As the conventional DC track circuits are found

vulnerable to the interference of currents generated by the thyristor/Chopper controlled

locomotives, joint less Audio Frequency track circuits have been found to be the solution in such

sections. The AFTC does not require insulated joints and can work for longer lengths and is

suitable for AC and DC electrified areas. These track circuits are more reliable because failures

due to block joint shorting are avoided, due to non-availability of joint and the train running is

very smooth.

1.6 LED signals for colour light signalling (LED)

In the colour light signals light aspects of mechanical signals are lit by incandescent bulbs. These

bulbs have limited hours of working and get fused due to ageing and voltage fluctuations. The

bulbs have to be replaced frequently. As an improvement, LED lit signals are now introduced.

LED signals are having longer life and better visibility. This type of signal has enhanced the

reliability by reducing the incidences of signal lamp fusing. It also affords good visibility to the

drivers and more signals are likely to be converted to LED signals.

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1.7 Replacement of over aged assets

Over aged signalling assets are normally to be replaced after a codal life of 25 years. Most of the

signal systems are obsolete mechanical type and no spares are now available in the trade. The

mechanical signals are operated from the mechanical lever frame from cabin. Most of the

signalling systems have become over-due for replacement.With the sanction of the Special

Railway Safety Fund the over aged assets are being replaced on priority basis.

1.8 Track circuiting

Track circuit detects the presence or absence of the train on the track. This is the backbone of the

signalling system. This ensures complete safety to the train in case of human failure. Due to high

utilisation of the track capacity, this ensures safe, speedy and punctual movement for train

services.

1.9 Level crossing

The unmanned gates are taken up for manning where telephone facilities are provided from the

nearest station so that gate will be closed well in advance before the train approaches the manned

gates. LC gates are being taken up for interlocking on the basis of train vehicle units (TVUs) to

ensure safety for both trains and road users.

1.10 Train protection & Warning system

This system will give information to the driver to regulate the train speed depending upon the

aspect of the signal in advance. In case, the driver fails to do so, the train will be automatically

stopped by applying brake without the intervention of the driver. This ensures that whenever any

train stops on the track, the following trains stop automatically, thus ensuring safety.

1.11 Train Actuated Warning Device

Whenever train approaches an unmanned level crossing, a hooters sounds giving warning to the

road users well in advance about the approach of the train thereby avoiding any accident.

1.12 Networking of Data Loggers

This is a modern equipment used for monitoring the operation of important functions like Track

circuits, Points, Signals, Battery chargers, Batteries etc. installed in Panel interlocked/RRI

installations. These are microprocessor-based equipment logging the events of the change of

status of the various functions in field and relay rooms and recording the precise time also. The

data loggers are useful devices for detecting the cases of passing the signal at danger by the

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driver and give important clues in case of accidents. The data loggers are also used as predictive

maintenance tools regarding deterioration of the performance of signaling gadgets.

1.13 Integrated Power Supply System (IPS)/ Non-conventional energy sources With the

introduction of more and more modern Electrical Signaling Systems, the dependency on the

power supply becomes more essential. To get reliable power supply, the concept of Integrated

Power Supply (IPS) has been introduced wherein, the different signal power supplies like 110

AC, 110 VDC, 24 DC etc. are derived from the common system, which works on common

battery, i.e. DC-DC converter, modular power packs.This IPS will enhance the working of the

signaling system especially in RE (Railway Electrification) area).

CHAPTER 7

OPTICAL FIBRE7.1 Need for OFC:

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a. Introduction-

The demand for bandwidth on transmission networks is increasing rapidly because video and

graphical rich contents are exchanged through the corporate network or the Internet. The Gigabit

Ethernet became commonly used in the corporate network backbone, and 10Gbit Ethernet will

be adopted in the near future. Meanwhile in the home, the demand for high-speed network

becomes popular as the wide spread of broadband access, e.g. CATV, XDSL, and FTTH. The

transmission medium with capability to transmit high bit rate signal is necessary to satisfy these

requirements. The telecommunication transport technologies move from copper based networks

to optical fibre, from timeslot based transport to wave length based transport, from traditional

circuit switching to terabit router and all optical based networks entering into a new era of optical

networking.

7.2. Basic physics of OFC-1. Optical Fibre Cable-

OFC have Fibres which are long, thin strands made with pure glass about the diameter of a

human hair. OFC consists of Core, Cladding Buffers and Jacket as shown in figure :

bare fibre and OFC cable

2. Monochromatic light, or single color light-

Light or visible light is electromagnetic radiation of a wavelength that is visible to the human eye

( about 400 – 700 nm). The word light is sometimes used to refer to the entire electromagnetic

spectrum. Light is composed of elementary particles called photons. Three primary properties of

light are:

Intensity or brightness

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Frequency or wavelength and

Polarization or direction of the wave oscillation

3. Incident ray, Reflected ray and Refracted ray-

An incident ray is a ray of light that strikes a surface. The angle between this ray and the

perpendicular or normal to the surface is the angle of incidence. Reflection is the change in

direction of a wave front at an interface between two different media so that the wave front

returns into the medium from which it originated. Common examples include the reflection of

light, sound and water waves. The reflected ray corresponding to a given incident ray, is the ray

that represents the light reflected by the surface. The angle between the surface normal and the

reflected ray is known as the angle of reflection. The Law of Reflection says that for a specular

(non-scattering) surface, the angle of reflection always equals the angle of incidence. The

refracted ray or transmitted ray corresponding to a given incident ray represents the light that is

transmitted through the surface.

light rays and its angles

4. Refractive index-

Refractive index is the speed of light in a vacuum ( c =299,792.458km/second) divided by the

speed of light in a material ( v ). Refractive index measures how much a material refracts light.

Refractive index of a material, abbreviated as ‘n ‘, is defined as ‘n=c/v ‘. Light travels slower in

physical media than it does when transmitted through the air. Refractive index (n): is a function

of molecular structure of matter; optical frequency, optical intensity; determines optical

propagation properties of each wavelength (λ) may not be distributed equally in all directions, is

affected by external temperature, pressure, and fields.

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5. Medium Index of Refraction-

6. Snell’s law-

In 1621, a Dutch physicist named Willebrord Snell derived the relationship between the different

angles of light as it passes from one transparent medium to another. When light passes from one

transparent material to another, it bends according to Snell's law which is defined as:

n1sin(θ1) = n2sin(θ2)

Where: n1 is the refractive index of the medium the light is leaving

θ1 is the incident angle between the light beam and the normal (normal is 90° to the interface

between two materials)

n2 is the refractive index of the material the light is entering

θ2 is the refractive angle between the light ray and the normal

Snell’s law gives the relationship between angle of incidence and angle of refraction.

Snell’s law

For the case of θ1 = 0° (i.e., a ray perpendicular to the interface) the solution is θ2 = 0°

regardless of the values of n1 and n2. That means a ray entering a medium perpendicular to the

surface is never bent.

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The above is also valid for light going from a dense (higher n) to a less dense (lower n) material;

the symmetry of Snell's law shows that the same ray paths are applicable in opposite direction.

7. Total internal reflection-

When a light ray crosses an interface into a medium with a higher refractive index, it bends

towards the normal. Conversely, light traveling cross an interface from a higher refractive index

medium to a lower refractive index medium will bend away from the normal. This has an

interesting implication: at some angle, known as the critical angle θc, light traveling from a

higher refractive index medium to a lower refractive index medium will be refracted at 90°; in

other words, refracted alon g the interface.

If the light hits the interface at any angle larger than this critical angle, it will not pass through to

the second medium at all. Instead, all of it will be reflected back into the first medium, a process

known as total internal reflection.

7.3 Merit & Demerit of OFC and its Application:1. Advantage of OFC communication

• More information carrying capacity fibbers can handle much higher data rates than

copper. More information can be sent in a second.

Information Carrying Capacities of various media are:

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5

• Free from Electromagnetic and Electrostatic interference

• Low attenuation: 0.25 dB/km at 1550 nm

2. Limitations of OFC

Difficulty in jointing (splicing)

Highly skilled staff would be required for maintenance

Precision and costly instruments are required

Tapping for emergency and gate communication is difficult.

Costly if under- utilised

Special interface equipment’s required for Block working

Accept unipolar codes i.e. return to zero codes only.

3. Application in Signal and Telecommunications

Long haul circuits for administrative branch and data transmission circuits

Short -haul circuits for linking of telephone exchanges.

Control communication & Signalling application for fail safe transmission

Electronic interlocking systems installations

7.4 Signal Attenuation in Optical Fibber Attenuation has three components:

- Bending loss (Macro / Micro)

- Absorption loss

- Scattering loss

In bending loss, there are 2 categories

- Macro bending loss (specified by manufacturer)

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- Micro bending loss (not specified but included in total attenuation accountable by

manufacturer)8

7.5 Factors causing absorption & attenuation• Scattering of light due to molecular level irregularities in the glass

• Light absorption due to presence of residual materials, such as metals or water ions, within the

fibre core and inner cladding.

• These water ions that cause the “water peak” region on the attenuation curve, typically around

1380 nm.

7.6 Construction of Optical Fiber Cable Core

Core is a central portion of the cable, in form of very thin tube size (approximately 8 um) made

up of glass and carries light signals from transmitter to receiver.

Cladding

It surrounds core cylindrically and is having lower refractive index as compared to the core.

Buffers

a. Primary coating Acrylate, silicon rubber or lecquer is applied as primary coating. It works as

mechanical protection1

b. Secondary coating An additional buffer (secondary coating) is also added during

manufacturing process.

Jacketing

Normally outer most sheath which is called jacketing provides protection from chemical acids,

alkalis, solvents etc. Material used are high density polyethylene with anti termite compound,

polyurethane, PVC, nylon etc.

Bending Parameters

The optical fibre and cable are easy to install because it is lightweight, small in size and flexible.

But precautions are needed to avoid tight bends, which may cause loss of light or premature fiber

failure.

Overall Diameter

The overall diameter of the cable shall not be more than 20 mm and uniform through out

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the length from top to end.

Fibre & Unit Identification

Fibres are coloured with readily distinguishable durable colours. In case of four fibres in a tube

the order of coloured fibres are Blue, Orange, Green and Natural. The 6 loose tubes have the

following colours:

Loose Tube number Colour of loose tube

1 Blue

2 Orange

3 Green

4 Brown

5 Slate

6 White

Chapter 8

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CONTROL8.1DIVISION

There are mainly seven division in railway which control by controlmaster. Control master

is a person who decide the track of railway or way of railway. In DRM office, for every

division provide a seprate room for each division control master and all station master are

under in controlmaster.

Bhatinda

Rewari

Sahranpur

Palwal

Umbala

Samali

Delhi area

Fig. 8

8.2 Railway Control Circuits: Railway Control Circuits are omnibus telephone circuits which

provide communication with each train working point, thus facilitating efficient train operation.

They should provide satisfactory and reliable communication between the controller and the

various way-side stations, important signal cabins, loco sheds, yard offices etc. all phone call and

all activity of control master are recorded.

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Fig.8.2

8.3 TYPE OF CONTROL SYSTEM: According to traffic requirements and to cater to the

needs of Electric Traction area, a section may be provided with one or more Railway Control

Circuits as detailed below :

a) SECTION CONTROL / TRAIN CONTROL : This is provided for communication between

the Section/Train Controller in the control office and wayside stations, junction station, block

cabins, loco sheds and yards in a division for the control of train movements and effective

utilisation of section capacity.

b) DEPUTY CONTROL : This is provided for communication between the Deputy Controller

in the control office and important stations, junctions & terminal stations, yard master's offices,

loco sheds and important signal cabins in a division for supervisory control of traffic operation in

general.

c) STOCK / ADM. CONTROL: This is provided for communication between the Stock/Adm.

Controller in the control office and yard master's offices at junctions and terminal stations in a

division for getting information on the movements of rolling stock.

d) LOCO POWER CONTROL : This is provided for communication between the Loco Power

Controller in the control office and the various loco sheds, important stations and yards division

for the optimum utilisation of the locomotives.

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e) TRACTION LOCO CONTROL : Provided between traction loco controller and loco sheds,

important Station Master's Offices for optimum utilisation of electric locomotives.

f) TRACTION POWER CONTROL : Provided between traction power controller and SM's

Office, FPs/SPs/SSPs for maintenance of OHE system.

g) S&T CONTROL : Provided between test room and way stations for effective maintenance of

S&T equipments.

h) EMERGENCY CONTROL: Provided from selected points along the track route for

establishing communication between train crew (in case of emergency), traction and permanent

way staff with traction power controller. The emergency sockets are provided on rail posts at an

interval of 1 Km (Max.) along the route.

a) EMERGENCY WIRELESS CONTROL COMMUNICATION: The following

equipments can also be utilized for emergency wireless communication where such system

exists:-

i) Handsets for Mobile Train Radio Communication (MTRC) in sections.

ii) Walkie-Talkie sets in sections where VHF communication from train to control office has

been provided in lieu of any physical medium or MTRC.

Any other form of emergency wireless communication shall have the specific approval of the

Railway Board

8.4 REQUIREMENTS FOR TRAFFIC TRAIN CONTROL SYSTEM :

a) Rotary keys or push buttons of non locking type shall be provided for selective calling of any

station by the controller.

b) Facilities should be provided for selectively calling one or a group of stations or all stations.

c) Means shall be provided to automatically inform the controller whenever the bell/buzzer at the

station rings in response to the call initiated by him.

d) The signalling used for selective calling shall not hamper normal telephone conversation on

the line.

e) Feature of prolonged ringing of any way-station shall be provided.

f) Adjustment and maintenance of the equipments in the control office and wayside stations

should be easy.

g) The equipment should be rugged and capable of intensive use.

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h) The equipment should work satisfactorily within allowable margins of line characteristics

without frequent critical adjustments.

i) The system should be capable of progressive expansion without any replacement.

j) The system should be compatible with overhead alignment and underground cables as

applicable.

k) Provision of intercommunication facility between several controllers in the same control

office may be incorporated in the control key board/panel wherever necessary.

l) Earth return circuits shall not be retained on AC traction and all Telecom circuits shall work on

metallic return.

m) Facility shall be provided in control office for transferring Emergency Control(wherever

exists) to Section Control circuit.

n) No overhead telecom alignment shall be within 50 meters from the AC electrified track except

when running strictly at right angles.

8.5 INTERCOMMUNICATION BETWEEN LOCAL TELEPHONE AND CONTROL

CIRCUIT

a) It is also desirable to make provision of an approved type to interconnect the local telephone

exchange with important control circuits to enable important officials served by the local

telephone exchange to gain access to such control circuits with or without the assistance of an

opertor.

b) Such a provision shall not affect the performance of the control circuits from the point of view

of signalling or speech.

c) Whenever interconnection is made through an operator, the manual board shall be provided

with necessary supervisory facilities so that the telephone connected to the exchange is

disconnected from the control circuit as soon as the conversation is over.

d) It should be ensured that only important officials have access to control circuits in this

manner.

8.6 TYPES: Traffic Control Equipments shall be of the following or any other

approved type.

(a) STC KEY SENDING SYSTEM: In this system the coded impulses are generated by means

of a rotary selector key (4001-A, 4002-A & 4002-B) mounted in a key case being turned at a

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time to call any particular station. The impulses are received at the way stations by polarized

relays or selectors (4301-A) adjusted to close the contact for the local ringing circuit for a

particular code.

(b) PUSH BUTTON SENDING SYSTEM : The Push Button Sending System consists of a

push button panel and an impulsing unit in the control office. The panel is equipped with 16 push

buttons, and any particular station being called by operating 2 buttons corresponding to the first

two digits of the code. For prolonged ringing, the long ring key is operated. All stations can be

signalled simultaneously by pressing a general call key.

(c) DUAL TONE MULTIFREQUENCY SYSTEM: In this system two frequencies are being

transmitted simultaneously as per the standard DTMF Frequencies plan given in Annexure-II

with 2 digit code to call either one station at a time or a nominated group at a time or all at the

same time.

8.7 INTERCOMMUNICATION EQUIPMENT: All controllers in a control office shall be

provided with an intercommunication system of approved type with facilities for each controller

to call any other controller, including Deputy Controller, Chief Controller and the

Telecommunication Maintainer/Inspector on duty.

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CONCLUSIONEngineering student will have to serve in the public and private sector industries and workshop

based training and teaching in classroom has its own limitation .The lack of exposure real life,

material express and functioning of industrial organization is the measure hindrance in the

student employment. In the open economy era of fast modernization and tough competition,

technical industries Should procedure pass out as near to job function as possible. Practical

training is one of the major steps in this direction. I did my training from Divisional Railway

Manager (DRM), New Delhi, India.

The training helps me in gaining depth knowledge about technologies used in development of

real life projects. I gain the knowledge of working as a team member in the team of developers

and they give me very good knowledge of how to work on different type of tools and

communicational environment. In the end, I hereby conclude that I have successfully completed

my industrial training on the above topics.

BIBLOGRAPHY & REFRENCES

I. BIBLOGRAPHY

Optical Fiber Communications: Principles and Practice (3rd Edition)

by JOHN M. SENIOR

Computer Networking for LANs to WANs: Hardware, Software and

Security By Kenneth C. Mansfield, Jr., James L. AntonakosII.

REFERENCES:

http://www.indianrailways.gov.in

http://www.authorstream.com

http://www.amazon.com

http://books.google.co.in/

Study material provided by railway training center