a overview of a exchange

8/14/2019 a overview of a exchange

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What is exchange?Exchange is define as a simply switch by virtue of

which we are able to communicate from one point to

another.Explanation about Telecommunication System :Telecommunication system requires electrical energy

for conversion of speech signals to electrical signals,

exchange switching, and transmission over a medium.

What are the components of communication system?Source converter media destination

Different components of communication system in detail:

SOURCE: it is a originating point at whichcommunication system in detail.

For example: when two person talking with each other

from different places, then they are talk with each other

through a system called telephone which we say A

source.

CONVERTER: converter is a component ofcommunication system that convert voice signal to

electrical signal.

For example :when a person is talking with another personthrough a source called telephone than his voice is not

reached to another person. A condition occur at which

voice signal is converted to electrical signal is called

converter.

MEDIA: media is a component of communicationsystem that is applied to convert the voice signal toelectrical signal. for example OFC{optical fiber cable}.

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CONVERTER: at this stage reconversion takesplace. it is a component of communication system that

convert electrical signal to voice signal. for example, when

two man talking with each other through telephone thanone man can hear the voice of other man through

converter.

DESTINATION: Destination is simply definedwhere system terminate. it is the point where we receive

the signal from a source called telephone on the other hand

we say it receiver called destination.POWER SUPPLY: it should be noted that in exchange

there must be 24 hours power supply.

In telecom system,dc power supply is only used.

-48v to -55v{dc}

it should be noted that there must be 24 hours power

supply or power supply should not be cut off for a minute.if this situation is ignore than there must be a great

damage in exchange. as a result exchange can destroy.

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Parts of exchangeSwitch roomMDF{main distribution frame}

FRS{fault record system}

Power plantE/A room {engine and alternator

room}

OMC{operation and

maintenance center}Cash counter

Mobile section

TransmissionFRS{fault record system}

AC plant room

Customer care center

TRA branch{telephone revenueaccount}3


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Supply system of exchange

It is clear that in telecom system only DC power supplyis used because of the following reasons:

1.harmonics of AC may effect the speech signals.

2.Relays used in telecom system are more sensitive to

DC than AC.

3.transistors and ICs etc,being unidirectional

devices, the use of DC has become necessary.

4.arranging standby source to AC is difficult compare

to DC for which secondary cells can be used as S/B

source.

5.Not hazardous to human life.

-In the exchange it should be noted that uninterruptedpower supply is used. Simply its mean that in the

exchange 24 hours power supply is required that means

the power supply should not be cut off for a minute. for

this we use another source called secondary or standby

source which comes in work when main source destroy.-For any uninterrupted power supply system twosources are required. that are main source or

secondary source {or standby source}.

What is main source?-Main source or normal source is one which supplies

power to the load round .Normal source is the source

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which is always in work. For example, in the Engine

and alternator room there are two ht panel, two

transformer or two generator. from them one is called

main source which is always in work.

What is standby source?Secondary or standby source is one which supplies

power to the load only during the absence of power

from normal source. For example in the E/A Room there

are two ht panel, two transformers or two generator.

each source is two. from them one is called main source

which is always in work or the other is called standbysource which play a role in the system when main

source is destroy.

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Sub-station room

Discussion about HT PANEL:In the HT panel there are present a relay or a circuit

breaker. There are present two HT panel one is called

main HT panel and other is called standby HT panel.

Standby HT panel works in the absence of main source.

It should be noted that PSEB transfer 11K supply to HTpanel.

Transfer of 11K 3 phase AC supply to the transformer:

Now 11K 3 phase AC supply transfers to the

transformer where it converted into 420K,3 phase ACsupply. there are also present two transformers which

play a role in the similar manner that is the HT panel.

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Control panel:

Now the transformers are connected to the control panel

where all the switches to control the transformer and

generator are located.

GENERATOR: Generator is also connected tocontrol panel .there are two generators which are

connected to the control panel. From them one is called

main generator or other is called standby generator.

Conversion of AC voltage to DCvoltage:

Rectifier is used to convert AC voltage to DC voltage.

It is simply defined as to arrive the strength of weak

signal.

OMC ROOM{operation and maintenance center}All type of controlling is done by OMC room, which

consist of a computer as a terminal Interface. OMC

room environment temperature between 20 degree to 24

degree C.

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OCB exchange working under Unix operating system,

for communication between human and exchange

through PC using windows NT environment. The

terminals control all the operation through commands.

PC: With the help of PC we check all the status ofexchange hardware. It show the alarm on terminal , if

any critical problem in the exchange .All the facility,

provided to the subscribers through this terminal .The

exchange data can also be analysis by DBMS packageslike FoxPro and visual FoxPro. For official work, on

this pc terminals used the software package MS office

2000{ MS-word,MS-excel,MS-access}.

On the exchange media OFC{optical fiber cable}PCM can be create, delete or modify and controlled

by this terminals.

From OMC room Now New communication

technology like WLL{wireless local loop}are control

from the pc terminals. The version of WLL is the bestthat is CDMA{code division multiple access}.WLL

has many advantages in landline, It is very successful

technology.

In the exchange media 4 terminals attached with

exchange .these four terminals are interconnectedthrough exchange. these four terminals are:

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1.CV1

2.CV2

3.CV3

4.CV4

CV stands for visual control

These four terminals are interconnected through

exchange if any terminals has been linked down, we canup the terminals with the help of other terminals.

Number of terminals attached to the exchange is

depends upon the How many number of user can be

communicate with exchange.

PC terminals increase or decrease at any time:

Parts of PC:

1.CPU

2.VDU

3.keyboard

4.mouse

5.CPU contains the following parts:

HDD,FDD,CD-ROM, Tape derive etc.

For produced the hard copy, used a DOT MATRIX

24 PIN and 132 columns printers. These printer are

direct attached with PC terminals Individual printer

attached the individual PC Terminals. One laser

printer are used only for print the official Documents.9


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INTERNET: In OMC ROOM on PC terminalsaccess the internet using a modem and telephone line.

Modem used for modulation and demodulation of

data. Now ISDN {integrated service digitalnetwork}technology used for high rate transferred of

Data.

BATTERY AND POWER PLANTThe power plant is usually referred asheart of

telecom system.

1.signaling 2.switching 3.transmission

----three basic requirements for power

supply:a. reliability of the components

b. free from noise and humidity

c. sensitivity

Source of Power: 1.AC mains 220V singlephase or 440V 3 phase 50 Hz.

2.S/B{standby}-S/B power supply like generator sets.

Types of power plant:

1.low size:5-12amp

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2.medium:25-50amp

3.Large size:100-180amp

Parts of power plant:1.Battery charger2.Float rectifier3.Switching cubical

4.Invertor

Battery charger +Filter circuit works as float rectifier.

Three way to use Battery:

1.charge discharge system

2.Standby battery system

3.Float battery system

-In OCB Exchange two battery SETA and SETB are

used having the capacity of one set is 2000 amp/h.

One set of battery consist of 24 cells. The Voltage ofone cell is 2.15 to 2.20.

In OCB exchange used a VRLA Battery{value

regulated lead acid}Battery used for maintenance

free.

Battery charge range from 44V to 65V.The maximum

volt in one cell 2.56V

WORKING: Exchange required a load51.5+_0.5

Hence exchange required-46V to 52V for working.

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CAPACITY OF BATTERY: capacity ofbattery:

Measure as Amp-hours.

Factors effecting the capacity of battery:1.Quantity and Condition of active material.

2.Design of Plates

3.Temperature of electrolyte.

4.Density and specific gravity of electrolyte.

5.The case at which the electrolyte can circulate

around the palter.6.The rate of discharge: Ampere Hour efficiency:

A/H efficiency= i*t/I*T*100

i=rate of discharge in Ampere

I=rate of charge in ampere

t=time of discharge in hours

T=time of charge in hours-Specific gravity of electrolyte decrease due to

discharge and vice versa capacity of battery

increase in temp in electrolyte. increase the capacity

of battery but decrease the battery life.

-Initial charge of battery: Requirement ofcharge of battery1.Building work

2.h2so4{distilled}

3.Battery charger

4.wiring

5.Measuring instrumentsSpecific gravity required 1840

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-Battery charge from 44 to 65v

The charge with in 24 hours during filling the

electrolyte in battery.

-Purpose of Initial charge:1.To soften the plates2.To convert pbso4 into heating active material.

Maintenance of battery:1.Avoid overcharging of battery

2.Avoid undercharging of battery

3.Avoid high acid temp4.Avoid high acid density

5.Proper maintenance.

Factors effecting the battery:1.High acid temp

2.High acid density

3.Overcharging

4.Undercharging

5.Bad maintenance

Routine Test/check of battery1. Pilot cell reading-daily

2. All cell reading-weekly

3. check of electrolyte-weekly

4. number of plates, Nuts & bolts-half yearly

Life of battery-10 to 15 yearsAfter the life of battery life is 15 years

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After the life of battery 75% to 80%capacity

it mean battery are dead.

OCB-283 system

Functional architecture: The alcatelE10 system is located at the heart of the

telecommunication networks concened. It is

made up of three independent functional

units: the subscriber access system

-connection and control

-operation and maintenance.

TIME BASE{BT}:The BT ensures timedistance for LR and PCM to provide the

synchronization, and also for working out the

exchange clock. Time distribution is tripled.

Time generation can be either autonomous or

slaved to an external rhythm with a view tosynchronize the system with the network.

SWITCHING MATRIX{SMX}:The SMX is a square connection matrix

matrix with a single time stage T ,duplicated

in full, which enables up to 2048 matrix

links{LR}to be connected. A matrix link LR14


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is an internal PCM, with 16 bits per

channel{32 channels}.

PCM controller {URM}The URM provides the interface betweenexternal PCMs and the OCB 283.These PCM

come from either:-A remote subscriber digital

access unit{CSN}or from a remote electronic

satellite concentrator{CSE}.

-Another switching center, on channel-associated signaling or CCITT NO :7.

-The digital recorded announcement

equipment auxiliary equipment

manager{ETA}

The ETA Supports:-the tone generator-The frequency receiving and

generation{RGF}devices,

-conference circuits{CCF},

-The exchange clock

CCS7 protocol handler{PUPE}andCCS7 controller{PC}:CCITT no.7 protocolprocessing

For connecting of 64 K bits signaling channels, semi-

permanent connections are established via the

connection matrix, to the PUPE which processes

the CCITT NO.7 protocol.

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CALL HANDLER{MR}:The MR is theresponsible for the establishment and breaking off

of communications-The call handler takes the

decisions necessary for processing ofcommunications in terms of the signalling received

,after consolations of the subscriber and analysis

database manager {TR}if necessary. The call

handler processing new calls and hanging-up

operations, releases equipment, commands

switching on and switching off etc. In addition, thecall handler is responsible for different

management tasks{control of tests of circuit, study

observations.

Subscriber and analysis database manager

{TR}{TRANSLATOR}.The TR functionscarries out management of the analysis, subscribers

and circuit group database.

The TR supplies the call handler ,on request from it,

with subscribers circuits characteristics necessary

for establishing and breaking off communications,

The TR also ensures match between the dialing

received and the addresses of the circuit groups or

subscribers{Pre-analyses, translations functions.

CALL CHARGING AND TRAFFIC

MEASUREMENT{TX}:The TX function carries out charging for

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TX is responsible for:

-calculating the amount to be charged for each

communication,

-keeping the charge account of each subscriber served

by the switching center,

-supplying the necessary information for drawing up

detailed billing, online to the OM.

IN addition, TX carries out tasks of observation of

circuits and subscribers observations.

MATRIX SYSTEM HANDLER{GX}The GX function is responsible for processing and for

defence of connections on receipt of:

-request for connection or disconnection coming from

call handler{MR}or message distributor

functions{MQ},

-connection faults signaled by the matrix switchcontroller function{COM}.

MESSAGE DISTRIBUTOR{MQ}The MQ function is responsible for distribution and

formatting of certain internal messages.but, above

all ,it carries out.

-supervision of semi-permanent connections{data

link},

-transmission of messages between the

communication multiplexes{gateway function}

COMMUNICATION MULTIPLEX:

One to five communication multiplexes are used totransmit message from one station two another.

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OPERATION AND MAINTENANCEFUNCTION{OM}:The functions of theoperation and maintenance subsystem are carried

out by the operation and maintenancesoftware{OM}.

The operating authority accesses all hardware and

software equipment of the Alactel 1000 E10 system

via computer terminals belonging to the operation

and maintenance subsystem. Consoles, Magnetic

media, intelligent terminal. these functions can begrouped into 2 categories:-

-operation of the telephone application

-Operation and maintenance of the system

In addition ,the operation and maintenance subsystem

carries out:

-loading of softwares and data for connection andcommand and for the subscriber digital access units,-

temporary backup of detailed billing information,

-centralization of alarm data coming from connection

and control station ,via alarm rings,

-Finally the operation and maintenance subsystem

permits two way communication with operation andmaintenance networks, at regional or national

level{TMN}

SMC: Main control station

SMA: auxiliary equipment control station.

SMT: Trunk control stationSMX: matrix control system

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SMM: maintenance station

STS: Synchronisation and time base station.

TRANSMISSION: media of transmission:1. MARR: multi-access radio relay

2. Digital MUX{multiplexing}

3. Digital UHF{ultra higher frequency}

4. Digital M/W{microwave}

5. Digital coaxial6. OFC

7. Satellite transmission

TYPES OF MARR SYSTEM:

1. 2/15 MARR SYSTEM

In the circuit 2 channels and 15 subscriber.

2. 4/30 system

In this system 4 channels and 30 subscriber extend

up to 36.

3. 8/60 8 channels and 60 subscriber extend up to 72.

MDF: {main distribution frame}:MDF combinethe switching equipment and external plant.

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All the line with in the exchange in are strike in

numerical order .Two conductor Jumper wire is used in

MDF{white and red}

Facilities provided by MDF:

1.permanently terminate of external point

2.Cross conducting External circuit to the

appropriate.

3.A mean path interconnection. Point for faultlocating.

:MDF one side is exchange side and other is line side.

ADVANTAGE OF MDF:1.Flexibility

2.Testing point

3.Protection from over voltage and current.

-For the protection of exchange two types fuses are

used:

1.DAF: Delay action fuse for protectionagainst higher current.2. GDT: Gas discharge tube for protection

against voltage surge {lightening etc}

GDT-when voltage is increased then it convertinto ions in GDT tube .it works as an insulator.

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Capacity of current-200mA when current more

than 350mA than it will operate as insulator.

MDF Tool :1.Wrapping Gun

2.Vacuum cleaner

3.Drill machine

OCB Exchange tag Block

1. Line side-100 pair tag block{10*10}

2. Xge side-128 pair tag block {10*8}

corDECT WIRELESS IN LOCALLOOP

The corDECT system has six major sub

systems. These are:

DECT Interface Unit{DIU}: Performs systemcontrol and interfaces to telecom network.

Compact Base Station{CBS}:Provides wireless access in the area on twelve

simultaneous channels.

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Wallset{WS}:A wireless fixed terminal, connected to any standard

telephone, modem or fax machine.

Handset{HS}:A portable telephone providing voice service to a

user.

Base Station Distributor{BSD}:

Connects four remotely located CBS to the DIU usingan EI link.

Network Management System {NMS}:Manages multiple DIUs and there associated CBS andWall sets each corDECT System comprises of one DIU,

20 compact base stations, and up to 1000 handsets or

wallsets, typically between 30-70 per CBS.A wallset

can be used up to 5km from a base station with a line-

of-sight-link, while a handset can be typically usedwithin 50-300 m from a base station depending on the

obstructions between the base station and itself. Each

base station is connected to the DIU using three pairs of

0.4 mm twisted pair cable. Alternatively, a base station

may be connected to a Base Station Distributor, which

itself is connected to a DIU on an EI optical fiber orradio link. To service subscribers in sparely populated

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areas, it is possible for a wallset to be programmed in a

special mode which would allow it to be used up to 10

kms from a base station with a line-of-sight-link. The

manner in which the corDECT subsystems are

interconnected.

DECT Interface Unit:

The DIU is a DECT exchange for wireless subscribers

and provides an interface to Public Switched TelephoneNetwork{PSTN}.functions such as call processing,

CBS powering, and PCM/ADPCM transcoding are

handled by the DIU. System operation and

maintenance{O&M},and remote fault monitoring can

be performed from theDIU or alternatively from a

remote location using the Network ManagementSystem.

Common Base Station:

The CBS is a small, unobtrusive, pole mounted or wall-

mounted unit. Each CBS serves one cell, providing upto 12 simultaneous speech channels. The cell radius

depends on the propagation environment and antenna

gain of the handset/wallset. Typically,it ranges from

0.1-5 kms.

Handset:

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The handset is a small, light weight portable unit

operated from re-chargeable batteries. It allows the user

to make calls from within the coverage area of the CBS

connected to one DIU. The handset has intelligence to

handover from one CBS to another. The same HS can

be used with different DIUs{say at home & office}by

appropriate re-registration when moving from one

location to another

.

Wallset:

The wallset is a small wall-mounted unit with an

external antenna and powered from a/c mains. An

internal battery provides backup in case of power

failure. The external antenna provides gain and extends

the range of a CBS in areas where CBS density is low.The wallset provides a standard RJ-11 telephone socket

so that any telephone, fax machine, modem or even a

payphone can be connected to it.

Base Station Distributor:

The Base Station Distributor is an optional unit used

when a cluster of CBS are to be located some distance

away from the DIU. The BSD is connected to the DIU

on EI lines and each E1 carries signals for four CBS.

Network Management System:

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The corDECT system provides a Network Management

System{NMS}which could be used to manage up to 30

DIUs and their subscribers.

Relay Base Station:

In order to extend coverage to 25kms.a relay base

station is required.

WIRELESS LOCAL LOOP SYSTEM

Introduction to WLL:

A Local Telephone System without wire line connected

to fixed radio communication system is known as

Wireless Local Loop.

What is Wireless Local Loop{WLL}? WLL is sometimes called fixed cellular.

WLL system can be treated as a wire line loop

system without wire line connected.

WLL is normally used for rural or unpopulatedareas.

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WLL can be quick solution fir developing

telephone infrastructure.

Why use WLL?

Eliminates many problems and reduce cost

inherent to wireline loop system in certain areas.

Decreases the time to deploy a network.

Mobility and flexibility.

Advantages of WLL

Ease of installation and deployment and lower

cost. Ease of operation, administration and

maintenance and lower cost.

Advantages over Mobile Bigger coverage area

Improved signal and reduced interference{fixed to fixed link}

Higher capacity

Fixed to fixed propagation

WLL propagation {fixed to fix} using freespace loss formulas based on 29db/sec.

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Mobile radio propagation {fixed to

mobile} based on 40db/sec.

UNDER A No-MULTIPATHCONDITIONANTENNA ARE PLACED AT HIGH

SPOTS OF BUILDING

C/I=10 dB under a non-fading fixed to fixed condition.

C/I=18 dB under a mobile radio condition.

Frequency reuse distance is reduced

DUE TO DIRECTIONAL ANTENNAS:

Fixed-to-fixed link {using directional antennas in

both ends}.

Mobile-to-fixed link {using directional antenna

on the end}.

DUE TO THE C/I

For C/I=10 dB, the frequency reuse distanceD equals 2.78 times the cell radius R.

For C/I=18 dB, the frequency reuse distance D

equals 4.6 times the cell radius R.

AN: Access Network ALM: Antenna Line Data Module

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E1: 2.048 Mbps PCM Link

EQN: Equipment number

ETSI: Euopian Telecommunications

Standards Institite

FITL: Fibre In The Loop

FRS: Fault Record System

FDMA: Frequency Division Multiple

Access FRFC:Float Rectifier Float Control

GPC:Global Path Control

GRRA:Global Routing and

Resource Allocation

GSM:Geographic Service Mobile HDT:Host digital Terminal

HTML:Hyper Text Mark up

Language

ISDN: Integrated Service Digital

Network

ITC: Indian Telephone Card

IMSI: International Mobile

Subscriber Identity

LE: Local Exchange

LCC: Line Connected Card

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LJU: Line Jointer Unit

LCD: Liquid Crystal Display

MDF :Main Distribution Frame

MMS: Multimedia Message Service

MAX: Main Automatic Exchange: A

Generic Term Used for C-DOT Family of

Switching Systems

MAX-L :Main Automatic Exchange-Large

MAX-XL: Main Automatic

Exchange-Extra Large

MMI: Man Machine Interface

ONU: Optical Network Unit OTP: Originating Terminal Process

OMC: Operation & Maintenance

center

OCB: Operation Control Bherison

PCM: Pulse Code Modulation

PSTN: Public Switched Telephone

Network

PHC: Protocol Handler Card

POTS: Plain Old Telephone System

PDA :Personal Digital Assistant

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PRA: Primary Rate Access

SMS: Short Message Service

SIM: Subscriber Identity Module

SMPS: Switch Mode Power Supply

SBM: Single Base Module

SCP: Status Control Process

SMH: Signalling Message Handler

SU: #7 Signalling Unit TTP: Terminating Terminal Point

TDMA: Time Division Multiple

Access

UPS: Uninterrupted Power Supply

V5.X:Standard Interface Specified byETSI between LE and AN

VU:V5 Unit

VRLA: Value Regulated Lead Acid

WLL: Wireless in local loop

SOME OTHER INFORMATION:

INDIAN TELECOMCARDS,ITC{VCC}:ITC service is also known as

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prepaid card calling service. This is a hard paper

card containing a secret card number printed on it.

Unlike a magnetic card, it is not used physically in

connecting a call. This service allows a user to makea call from any telephone any destination by using

this card number and charges are debited his ITC

without any charging on the telephone number used

for making such a call by Card holder.

PREPAID CALLING CARDS OF THE FOLLOWINGDEMONATIONS ARE AVAILABLE:

a. Rs.102/-for making local calls

b. Rs.216/-foe making local and STD calls

c. Rs.524/-for making local, NSD&ISD

calls

FACILITIES AVAILABLE IN ELECTRONIC

EXCHANGES

1.DYNAMIC LOCKING/UNLOCKING OF

STD CALLS: This facility is available in allelectronic exchange except C-DOT-128 and NEAX

exchange. By using this facility the subscriber can

lock/unlock ISD/NSD/RSD calls, so as to avoid

misuse. This procedure in different exchanges is as

given on page no. XLVIII.

2.CALL WAITING{ALERT}FACILITY32


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3.Wake up/Reminder Call facility

4.Hot Line

5 . Abbreviated Dialing

6 .Call TransferCLI{calling line identification}

8.Computerized Automatic

Switching RoomSwitch Room Consists of Different

Racks

SMM RACK: Multi System Multi station

SMC RACK:Main Control Station SMX RACK: Switching Matrix SMA RACK:Auxiliary Multi Station

CSN RACK:Subscriber Rack{digital network concentrated }

SMT RACK: Trunk Multiple Station

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SMM Rack is the head of exchange .All type of

programming is control through this rack. This rack

may be divided into two parts: SMMAA. &

SMMA B.SMM b. Rack consists of the followingparts:

GX

MR

TR

MQ PC

SMC Rack : in this rack all the facility of the

subscriber are store in this rack like Lock facility ,

out going calls and incoming calls, CLIP ,

STD/ISD etc.SMX :- All the call made through this rack. SMX

give the route for destination.

SMA : In this rack all the secondary function

performed .

CSN : All the subscribers Numbers are

terminate in this rack . CSN rack connect the

exchange side and subscribers .

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SMT :- In the Rack all the PCM are terminate

in this rack. SMT RACK connect with TAX

exchange through OFC.

Sign of Co-ord (T&P) Sign. Of officer in charge Training

SLIET Of organization.

CONTENTS/INDES

1. About Exchange

2. Detail about components of

communication system

3. Parts of exchange

4. Connection in the E/A room

5. OMC room

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6. PC

7. Internet

8. Battery and Power Plant

9. Types Of Power Plant10.Parts of power plant

11.OCB-283 system

12.Transmission

13.MDF

14.CorDECT WLL15.WLL

16.Abbreviations

17.Other information

18.Switch room