INDUSTRIAL TRAINING PRESENTATION

PRESENTED BY:PUNEET KUMAR

STUDENT OF ECE DEPARTMENT

ROLL NO: 1214331110

MTNL

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CONTENTS

Introduction to company.Training Profile.Telephony.Switching Network.Types of switches.Types of Exchanges.Transmission Network.Optical fibers.Splice.

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INTRODUCTION TO COMPANY

MTNL stands for Mahanagar Telephone Nigam Limited .It is state-owned telecommunication service provider in the metro cities Mumbai & New-Delhi in India.“Transparency makes us different” is the motto of the company.MTNL was set up on 1 April 1986 by the Government of India with the aim of upgrading the quality of telecom services, expanding the telecom network, introducing new services & raising revenue for the telecom development. Its main goal is to remain market leader in providing world class telecom & IT related services at affordable prices & be a global player. It also aims at venturing into other areas in India and abroad on strengthening to compete with core companies.

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TRAINING PROFILE

While undergoing training at ITTM the following topics were explained and Labs were imparted on them :-

TELEPHONY

SWITCHING NETWORK

TRANSMISSION NETWORK

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INTRODUCTION TO TELEPHONY

What is a Telephone ?A device to speak over long distances, much beyond their range of voice.

• 1876 - First Basic Telephone designed by Alexender Graham Bell.

•1882 - First telephone exchange established in Calcutta.

•1911 - First telephone exchange established in Delhi.

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A Basic Telecommunication System

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FUNCTIONAL REQUIREMENTS OF A TELEPHONE SET

1. To indicate a Received call by means of some audible signalling components.

2. Apply an answering condition to stop the ringing condition.

3. Convert speech energy into electrical Energy for transmission to distant telephone.

4. Convert Received electrical energy to acoustical energy.

5. Disconnect call at the completion of conversation.

6. Generate electrical information from Transmitter to establish a call to another telephone service.

8COMPONENTS OF A TELEPHONE INSTRUMENT

• Transmitter

Carbon Type- Converts acoustical energy to electrical energy.

• RECEIVER

Magnetic Diaphragm Type-Converts electrical energy into acoustical energy.

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PROGRESS OF EXCHANGESManual Exchanges---- Magneto & CB (Central Battery) Mostly used in Railways..(All calls were connected by operators manually)

AUTOMATICPABX(Private Automatic branch Xges).. Extn to Extn calls were automatic—OG & IC were thru operators…..(Some given 0 facility to get direct junctions.)Strowger -Step By step Control (Call process under control of digits dialled by Sub.)Cross-Bar – Common Control Equipment ---The CCE is seized only during call establishment.SPC(store Programme Control)- All softwares like call processing,subs database ,maintenance & Operating System all are stored in memory of Central Processor-Analog Switching.Digital Exchanges– E10B --- OCB283 --- AXE10--- 5ESS --- EWSD

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SWITCHING NETWORK

Switch:Control consisting of a mechanical or electrical or electronic device for making or breaking or changing the connections in a circuit.

And the process is called SWITCHING.

Control

123

N

123

N

Connectionof inputs to outputs

… …

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WHAT IS AN EXCHANGE

The prime purpose of an exchange is to provide a temporary path for simultaneous, bidirectional transmission of speech between• Subscriber lines connected to same exchange(Local

Switching)• Subscriber lines and trunks to other

exchanges(Outgoing trunk call) • Subscriber lines and trunks from other exchanges

(Incoming trunk call) and• Pairs of trunks towards different exchanges(transit

switching) These are switching functions of an exchange & are implemented through the equipment called the Switching Network. . Cont…

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WHAT IS AN EXCHANGE

Strowger Exchange, the first automatic exchange having direct control feature, appeared in 1892 in Le Porte.

The first electronic exchange employing space-division switching (Analog Switching) was commissioned in 1965 at New Jersey.

This exchange used one physical path for one call and hence full availability could not be achieved.

Further research resulted in development of time division switching(Digital Switching) which enabled sharing a single path by several calls ,thus providing full availability.

The first digital exchange was commissioned in 1970 at Brittany, France.

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Electromechanical Exchanges Electronic Exchanges

Category, Analysis, Routing, translation, etcdone by relays.

Translation, speech path Sub’s Facilities, etc., managed by MAP and other DATA.

Any changes in facilities require addition of hardware and/or large amount of wiring change. Flexibility limited.

Changes can be carried out by simplecommands. A few changes can be made by Subs himself. Hence, highly flexible.

Testing is done manually externally and is time consuming. No logic analysis carried out.

Testing carried out periodically automatically and analysis printed out.

Partial full-availability, hence blocking.limited facilities to the subscribers.

Full availability, hence no blocking. A large number of different types of services possible very easily.

Slow in speed. Dialing speed is max. 11 Ips and switching speed is in l milliseconds.

Very fast. Dialing speed up to 11 digits /sec possible. Switching is achieved in a few microseconds.

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Hierarchical network long level network (Star Connection)

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MODERN TYPES OF SWITCHES

(1)OCB-283 – Organ command or controlled Bhersion 2nd generation 8300 motorola

Microprocessor.(By Alcatel Lucent)

(2) EWSD - Electronic World Switch Digital.(By Siemens )

(3) 5ESS - Made by Alcatel Lucent. (4) AXE 10 – Made by  Ericsson.

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TRANSMISSION NETWORK

• The transmission medium is the physical path by which a message travels from sender to receiver.• Computers and telecommunication devices use signals to represent data.• These signals are transmitted from a device to another in the form of electromagnetic energy.• Examples of Electromagnetic energy include power, radio waves, infrared light, visible light, ultraviolet light, and X and gamma rays. • All these electromagnetic signals constitute the electromagnetic spectrum

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TYPES OF TRANSMISSION MEDIA

• Guided Media Twisted Pair Co axial Cable Optical Fiber Cable• Unguided Media Radio waves Transmission Microwave Transmission Infrared Transmission Laser Transmission Satellite Transmission In Telephone sector majorly we

depend upon Guided media.

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Transmission Process

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GUIDED MEDIA

21Twisted-Pair Cable Coaxial Cable

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Optical Fiber

Optical fiber is a new medium, in which information (voice, data or video) is transmitted through a glass or plastic fiber, in the form of light

Fiber ConstructionConsists of Core and CladdingCore and Cladding are made up of same materialThe material used is optically transparentSilica or borosilicate glass will be the usual materialThe R.I of the core will be slightly higher than the R.I of the cladding

23Advantages of Optical Fiber

Optical Fibers are non conductive (Dielectric).Electromagnetic immunity. Large Bandwidth (> 50 GHz for 1 km length).Low Loss (5 dB/km to < 0.25 dB/km typical).Small, light weight cables.Available in Long lengths (> 12 kms).Secured.Theft prove.

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Light Propagation Through OFC

Rarer to Denser medium - Refracted rays move towards the normal

Denser to Rarer medium - Refracted rays move away from normal

Critical angle:- The angle of incidence in the denser medium for which the angle of refraction is 90

When the angle of incidence is greater than the critical angle, Total Internal Reflection occurs

Refractive Index of core is 1.48 Refractive Index of cladding is 1.46 Permissible loss in OFC is 0.3db/km(practical).

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Total Internal Reflection

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Splice

Permanent connection between two fibers. Involves cutting of the edges of the two fibers to

be spliced. Alignment of the cores of the fibers to be

connected is important to reduce splice loss.

Splicing Methods

Single Fiber Mechanical splicing. Adhesive bonding or Glue splicing. Temp. Mechanical splicing. Fusion Splicing.

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Fusion Splicing

Most popular splicing technique. Achieved either through electrical arc or through gas

flame. Splicing loss can be minimized as low as 0.01

dB/joint. Splice joint needs mechanical protection and

protection from moisture. For this epoxy resin coating and heat shrinkable tube are used.

Suitable for SMF for use in long haul network. The splice loss indicated by the splicing

machine is only an estimated loss. After every splicing is over, the splice loss

measurement is to be taken by an OTDR.

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REFRENCES

https://en.wikipedia.org/wiki/MahanagarTelephone_Nigam mtnl.ingoogle.co.in/mtnlMtnl study material.

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THANKS