Training report on telecom exchange2

TRAINING REPORT ON TELECOM EXCHANGE

SIX WEEK INDUSTRIAL TRAININGAT

BHARAT HEAVY ELECTRICALS LIMITEDRANIPUR, HARIDWAR (UTTARAKHAND)

Submitted To: Submitted By:

Mr. Vikas Singla Raghav Aggarwal

Dy. Manager, Tel B.Tech (ECE)

SMVDU

ACKNOWLEDGEMENT

“An engineer with only theoretical knowledge is not a complete engineer. Practical knowledge is very important to develop and apply engineering skills”. It gives me a great pleasure to have an opportunity to acknowledge and to express gratitude to those who were associated with me during my training at BHEL.

I am very great-full to Mr Vikas Singla for providing me with an opportunity to undergo training under his able guidance.

Furthermore, special thanks to Mr P. K. Joshi for his help and support in Haridwar. Last, but not the least, I would also like to acknowledge the immense pleasure, brought about by my friends Prem , Munish , Naveen as they pursued their training along with me. We shared some unforgettable moments together.

I express my sincere thanks and gratitude to BHEL authorities for allowing me to undergo the training in this prestigious organization. I will always remain indebted to them for their constant interest and excellent guidance in my training work, moreover for providing me with an opportunity to work and gain experience.

VACATIONAL TRAINING

A Major Project Report

Submitted by

Mr RAGHAV AGGARWAL(2010EEC30)

In partial fulfilment for the award of the degree

Of

BACHLEOR OF TECHNOLOGY

IN

ELECTRONICS & COMMUNICATION ENGINEERING

At

SCHOOL OF ELECTRONICS AND COMMUNICATION ENGINEERINGSHRI MATA VAISHNO DEVI UNIVERSITYKATRA

July 2013

Contents

1. INTRODUCTION

2. BHEL Haridwar – An Overview

3. BHEL – A Brief Profile

4. INTRODUCTION TO TELECOMMUNICATION

5. INTRODUCTION TO TELECOM EXCHANGE

5.1 MAX

5.2 PABX

6. COMPONENTS OF TELECOM EXCHANGE

6.1 MDF

6.2 IDF

6.3 LINE CARDS

6.4 JUNCTION LINES

7. DLC

8. OFC

9. PRI

10. FACILITY OF TELEPHONE

11. References

1. INTRODUCTIONBHEL was established more than 50 years ago when its first plant was setup in Bhopal ushering in the indigenous Heavy Electrical Equipment Industry in India. A dream which has been more than realized with a well-recognized track record of performance it has been earning profits continuously since 1971-72 and will achieve a turnover of Rs 134,000 crore for the plan year 2012, showing a growth of 50% in the plan. Bharat Heavy Electricals Limited is country’s ‘Navratna’ company and has earned its place among very prestigious national and international companies. It finds place among the top class companies of the world for manufacture of electrical equipments.

BHEL caters to core sectors of the Indian Economy viz., Power Generation's & Transmission, Industry, Transportation, Telecommunication, Renewable Energy, Defence, etc. BHEL has already attained ISO 9000 certification for quality management, and ISO 14001 certification for environment management and OHSAS – 18001 certification for Occupational Health and Safety Management Systems. The Company today enjoys national and international presence featuring in the “Fortune International -500” and is ranked among the top 10 companies in the world, manufacturing power generation equipment. BHEL is the only PSU among the 12 Indian companies to figure in “Forbes Asia Fabulous 50” list.

Probably the most significant aspect of BHEL’s growth has been its diversification .The constant reorientation of the organization to meet the varied needs in time with a philosophy that has led to total development of a total capability from concepts to commissioning not only in the field of energy but also in industry and transportation.

In the world power scene BHEL ranks among the top ten manufacturers of power plant equipments not only in spectrum of products and services offered, it is right on top. BHEL‘s technological excellence and turnkey capabilities have won it worldwide recognition. Over 40 countries in world over have placed orders with BHEL covering individual equipment to complete power stations on turnkey basis.

BHEL has a share of 59% in India’s total installed generating capacity contributing 69% (approx.) to the total power generated from utility sets as of March 31, 2012. The company has been exporting its power and industry segment products and services for over 40 years. BHEL’s global references are spread across 75 countries. The cumulative overseas installed capacity of BHEL manufactured power plants exceeds 9,000 MW across 21 countries including Malaysia, Oman, Iraq, the UAE, Bhutan, Egypt and New Zealand.

2. BHEL – An Overview

BHEL today is the largest Engineering Enterprise of its kind in India with excellent track record of performance, making profits continuously since 1971-72.

BHEL's vision is to become a world-class engineering enterprise, committed to enhancing stakeholder value. The company is striving to give shape to its aspirations and fulfil the expectations of the country to become a global player.

BHEL business operations cater to core sectors of Indian Economy.

Power

Industry

Transportation

Transmission

Defences etc.

The greatest strength of BHEL is its highly skilled and committed 60,000 employees. Every employee is given an equal opportunity to develop himself and grow in his career. Continuous training and retraining, career planning, a positive work culture and participative style of management all these have engendered development of a committed and motivated workforce setting new benchmarks in terms of productivity, quality and responsiveness.

3. BHEL – A BRIEF PROFILE

BHEL is the largest engineering and manufacturing enterprise in India in the energy related infrastructure sector today. The wide network of BHEL's 14 manufacturing division, four power Sector regional centres , over 150 project sites, eight service centres and 18 regional offices, enables the Company to promptly serve its customers and provide them with suitable products, systems and services – efficiently and at competitive prices. While the company contributes more than 75% of the national grid, interestingly a share of 45% comes from its single unit. And this is none other than BHEL-HARIDWAR

BHEL has:-

Installed equipment for over 90,000 MW of power generation--- for utilities captive and industrial users.

Supplied over 2, 25,000 MVA transformer capacity and other equipment operating in transmission and distribution network up to 400 kV (AC & DC).

Supplied over 25,000 motors with drive control systems to power projects, petrochemicals, refineries, steel, aluminium, fertilizers, cement plants etc.

Supplied Traction electrics and AC/DC locos to power over 12,000 kms railway network.

Supplied over one million valves to power plants and other industries.

4. INTRODUCTION TO TELECOMMUNICATION

Telecommunication  is communication at a distance by technological means, particularly through electrical signals or electromagnetic waves

Early telecommunication technologies included visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs Other examples of pre-modern telecommunications include audio messages such as coded drumbeats, lung-blown horns, and loud whistles. Electrical and electromagnetic telecommunication technologies include telegraph, telephone, and teleprinter, networks, radio, microwave transmission, fibre optics, communications satellites and the Internet.

The conventional telephone now in use worldwide was first patented by Alexander Graham Bell in March 1876 that first patent by Bell was the master patent of the telephone, from which all other patents for electric telephone devices and features flowed. Bharat Sanchar Nigam Limited (abbreviated BSNL) is an Indian state-owned telecommunications company headquartered in New Delhi, India. It is the largest provider of fixed telephony and fourth largest mobile telephony provider in India, and is also a provider of broadband services. However, in recent years the company's revenue and market share plunged into heavy losses due to intense competition in the Indian telecommunications sector.

BSNL is India's oldest and largest communication service provider (CSP). It had a customer base of 95 million as of June 2011. It has footprints throughout India except for the metropolitan cities of Mumbai and New Delhi, which are managed by Mahanagar Telephone Nigam (MTNL).

The first commercial telephone services were set up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven, Connecticut, and London, England

BHEL also caters to telecommunication sector by way of small, medium and

large switching system.

5. INTRODUCTION TO TELEXCOME EXCHANGE

A telephone exchange is a telecommunications system used in the public switched telephone network or in large enterprises. An exchange consists of electronic components and in older system also human operators that interconnect (switch) telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.

In the public telecommunication networks a telephone exchange is located in a central office (CO), typically a building used to house the inside plant equipment of potentially several telephone exchanges, each serving a certain geographical exchange area. Central office locations are designating a facility from which a telephone obtains dial tone. For business and billing purposes, telephony carriers also define rate centres, which in larger cities may be clusters of central offices, to define specified geographical locations for determining distance measurements

For corporate or enterprise use, private telephone exchanges are often referred to as private branch exchanges. They are installed in enterprise facilities, typically collocated with large office spaces or within an organizational campus to serve the local private telephone system and any private leased line circuits. Smaller installations might deploy a PBX or  key telephone system in the office of a receptionist.

In the U.S. and Canada, the Bell System established in the 1940s a uniform system of identifying each telephone exchange with a three-digit exchange code, or central office code that was used as a prefix to the local telephone station number. All exchanges within a larger region, typically aggregated by state, were assigned a common area code. With the development of international and transoceanic telephone trunks, especially driven by direct customer dialling, similar efforts of systematic organization of the telephone networks occurred in many countries in the mid-20th century.

5. TYPE OF EXCHANGES

MAX (Main Automatic Exchange)

PABX (Private automatic branch exchange)

BHEL has established MAX and PABX exchanges in Haridwar Unit with calibration with BSNL

5.1 MAX (Main Automatic Exchange)

A MAX is) is a telephone system within an enterprise that switches calls between enterprise users on local lines while allowing all users to share a certain number of external phone lines. The main purpose of a MAX is to save the cost of requiring a line for each user to the telephone company's central office.

The MAX is owned and operated by the enterprise rather than the telephone company (which may be a supplier or service provider, however). Private branch exchanges used analog technology originally. Today, MAXs use digital technology (digital signals are converted to analog for outside calls on the local loop using plain old telephone service (POTS ).

A MAX includes:

Telephone trunk (multiple phones) lines that terminate at the MOX

A computer with memory that manages the switching of the calls within the MOX and in and out of it

The network of lines within the MAX

A console or switchboard for a human operator (optional)

In some situations, alternatives to a MAX include centrex service (in which a pool of lines are rented at the phone company's central office), key telephone systems, and, for very small enterprises, primary rate Integrated Services Digital Network (ISDN).

In MAX all users (phone no.) are not connected to PSTN directly. They are connected to PSTN by an operator. In general we can provide different facility to different users like some users are provided full connection (incoming and outgoing to outer network), normal connection (incoming from outer network) and basic connection (for calling inside the own network)

In MAX if Mr X from other network wants to call Mr Y then his call is connected to operator and operator connects the call to Mr Y’s NO. By this way call is completed. In this type of exchanges has a very big disadvantage that if the Mr Y is not his place still caller has to pay means money is charged without even call reached at his destination.

Initially, the primary advantage of MAXs was cost savings on internal phone calls: handling the circuit switching locally reduced charges for local phone service. As MAXs gained popularity, they started offering services that were not available in the operator network, such as hunt groups, call forwarding, and extension dialling

It is also famous by the name of intercom

BHEL had established MAX in the beginning but it is now replaced by a PABX

5.2 Private automatic branch exchange

A private automatic branch exchange (PABX) is an automatic telephone switching system within a private enterprise. Originally, such systems - called private branch exchanges (PBX) - required the use of a live operator. Since almost all private branch exchanges today are automatic, the abbreviation "PBX" usually implies a "PABX."

Lucent Technologies, Northern Telecom (NORTEL), Rolm/Siemens, NEC, GTE, Intecom, Fujitsu, Hitachi and Mitel are among the larger manufacturers of PABX.

In BHEl Haridwar a PABX exchange is established with calibration with BSNL. Four thousand numbers are provided to BHEL starting with 1,2,4,5 of ten thousand numbers (0000 – 9999).we can connect a call in BHEl to specific number by dialling Haridwar std code (01344) and 28XXXX

The remaining numbers are either provided to other companies or reserved for future usage. The call reaches its destination with going through operator so it is cost efficient

6. COMPONENTS OF TELECOM EXCHANGE

6.1 MAIN DISTRIBUTION FRAME (MDF):

MDF is a media between switching network and subscriber’s line. It distributes wires in different areas and the wire containing switching room and subscriber’s line.

MDF has following components:

Vertical Frame

No of equipments

Module

Selector

Wires and cables

6.2 Intermediate distribution frame

An intermediate distribution frame (IDF) is a distribution frame in a central office or customer premises, which cross-connects the user cable media to individual user line circuits and may serve as a distribution point for multipair cables from the main distribution frame (MDF) or combined distribution frame (CDF) to individual cables connected to equipment in areas remote from these frames.

IDFs are used for telephone exchange central office, customer-premise equipment, wide area network (WAN), and local area network (LAN) environments, among others.

In central office environments the IDF may contain circuit termination equipment from various auxiliary components. In WAN and LAN environments IDFs can hold devices of different types including backup systems (hard drives or other media as self-contained, or as RAIDs, CD-ROMs, etc.), networking (switches, hubs, routers), and connections (fiber optics, coaxial, category cables) and so on.

6.3 Line cardA line card  or digital line card  is a modular electronic circuit on a  printed circuit board that interfaces with a telecommunications access network.

A line card typically interfaces the  twisted pair cable of a POTS local loop to the public switched telephone network (PSTN). Telephone line cards perform multiple tasks, such as analog-to-digital and digital-to-analog conversion of voice, off-hook detection, ring supervision, line integrity tests, and other BORSCHT functions. In some telephone exchange designs, the line cards generate ringing current and decode DTMF signals. The line card in a subscriber loop carrier is called a subscriber line interface card (SLIC).

Northern Telecom World Line Card NT6X17BA, circa 1995

A line card can terminate a line supporting voice POTS service, ISDN service, DSL service, or proprietary ones. Some line cards are capable of terminating more than one type of service.

Since an access network element is usually intended to interface many users (typically a few thousand), some exchanges have multiple line terminations per card. Likewise, one network element can have many line cards

6.3 junction lines

These are the traditional telephone lines made from copper wire which is also analogue switchboard telephone lines.

Even though they are analogue, they work very effectively they work very effectively and are the most common PABX telephone

Analog telephone lines transmit voice as electrical signals. When you speak into the handset of your phone, the microphone converts the sound waves into analog electrical waves. These waves propagate over the telephone line to their destination. The receiving phone then converts the electrical signals back into sound waves through the speaker of the handset.

Other names for analog telephone lines:

Analog telephone lines are referred to in a variety of ways. Here are some of the terms you may hear from an installation professional or a service provider

C.O. Line – Refers to the fact that the line connects you to the Central Office

Copper Line – Refers to the historical medium that carries analog signals, namely copper

POTS Line – Plain Old Telephone Service

Analog Line – Refers to the analog electrical signal used to transmit voice

Good points to remember about analog telephone lines are that

One phone number is associated with one line One line can handle one conversation at a time; when the line is in use, a busy

signal is heard

DLC eliminates the need for these remedies by extending out closer to the customer the line card which digitises the voice signal for use by the PSTN. Once the voice signal is digitised, it is easily manipulated and is no longer subject to the vagaries of the analog loop caused by distance, impedance, attenuation and noise

7. Digital loop carrierA digital loop carrier (DLC) is a system which uses digital transmission to extend the range of the local loop farther than would be possible using only twisted pair copper wires. A DLC digitizes and multiplexes the individual signals carried by the local loops onto a single DataStream on the DLC segment.

Reasons for using DLCs:

Subscriber Loop Carrier systems address a number of problems:

Electrical constraints on long loops.

Insufficient available cable pairs.

Cable route congestion (inability to add cable due to lack of space, particularly in urban street, bridge, and building conduit)

Construction challenges (in areas of difficult terrain) when limited cable pairs are already available

Expense due to cable cost and the associated labour-intensive installation work

In a typical configuration, DLC remote terminals are installed in new neighbourhoods or buildings as a means of reducing the labour and complexity of installing individual local loops from the customer to the central office (CO). A fibre optic cable or several copper pairs for the whole system from the CO to the DLC remote terminal replace the individual pair previously needed for each loop. DLC remote terminals are typically stored in Serving Area Interfaces–metal cabinets alongside or near roadways that overlie communications rights-of-ways.

With the growth in popularity of digital subscriber line (DSL) and the benefits provided by shorter metallic loops used with DLC systems, digital loop carriers are sometimes integrated with digital subscriber line access multiplexers (DSLAM), both systems then taking advantage of the digital transmission link from the DLC to the CO.

8. Fiber-optic communicationFiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information. First developed in the 1970s, fiber-optic communication systems have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks in the developed world.

The process of communicating using fiber-optics involves the following basic steps: Creating the optical signal involving the use of a transmitter, relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak, receiving the optical signal, and converting it into an electrical signal.

Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals. Due to much lower attenuation and interference, optical fiber has large advantages over existing copper wire in long-distance and high-demand applications. However, infrastructure development within cities was relatively difficult and time-consuming, and fiber-optic systems were complex and expensive to install and operate. Due to these difficulties, fiber-optic communication systems have primarily been installed in long-distance applications, where they can be used to their full transmission capacity, offsetting the increased cost. Since 2000, the prices for fiber-optic communications have dropped considerably. The price for rolling out fiber to the home has currently become more cost-effective than that of rolling out a copper based network

Modern fiber-optic communication systems generally include an optical transmitter to convert an electrical signal into an optical signal to send into the optical fiber, a cable containing bundles of multiple optical fibers that is routed through underground conduits and buildings, multiple kinds of amplifiers, and an optical receiver to recover the signal as an electrical signal. The information transmitted is typically digital information generated by computers, telephone systems, and cable television companies.

9. Primary Rate Interface

The Primary Rate Interface (PRI) is a standardized telecommunications service level within the Integrated Services Digital Network (ISDN) specification for carrying multiple DS0 voice and data transmissions between a network and a user.

PRI is the standard for providing telecommunication services to offices. It is based on the T-carrier (T1) line in the US and Canada, and the E-carrier (E1) line in Europe. The T1 line consists of 24 channels, while an E1 has 32.

The Primary Rate Interface (PRI) consists of 23 64-kbit/s B-channels and one 64-kbit/s D-channel using a T1 line, often referred to as "23B + D", (North American and Japanese standard) or 30 B-channels and two D-channels using an E1 line (Europe/rest of world), often referred to as "30B + 2D". A T1 Primary Rate Interface user would have access to a 1.472-Mbit/s data service. An E1 Primary Rate Interface user would have access to a 1.920 Mbit/s data service Larger connections are possible using PRI pairing. A dual PRI could have 24+23= 47 B-channels and 1 D-channel (often called "47B + D"), but more commonly has 46 B-channels and 2 D-channels thus providing a backup signalling channel. The concept applies to E1s as well and both can include more than 2 PRIs. Normally, no more than 2 D-channels are provisioned as additional PRIs are added to the group.

The Primary Rate Interface channels are typically used by medium to large enterprises with digital PBXs to provide them digital access to the Public Switched Telephone Network (PSTN). The 23 (or 30) B-channels can be used flexibly and reassigned when necessary to meet special needs such as video conferences. The Primary Rate user is hooked up directly to the telephone company central office..

PRI provides a varying number of channels depending on the standards in the country of implementation. In North America and Japan it consists of 23xB (B channels (be/s). In Europe and Australia it is 30xB + 1xD on an E1 2.048 Mbit/s. One timeslot on the E1 is used for synchronization purposes and is not considered to be a B or D channel.

10. Facility of telephone

Facility to subscriber

A line can be made outgoing and incoming or outgoing Hotline facility (immediate and delayed hotline) Abbreviated dialling Conference between more two subscribers Automatic call back on busy Priority line Malicious call identification Detailed Billing

Facility to digital subscriber

Digital subscribers are provided with all facility provided to analog subscriber along with following facility which are called ISDN services. An ISDN subscriber can use many electronics devices with telephone devices and can use them for two or more simultaneous calls for either

VOICE DATA VIDEO TELETEXT 2,3,4 FACIMINE CALL TRANSFER FACILITY

11. REFERENCES

1. Wikipedia

2. www.seminarprojects.com

3. Google Image Results

4. Johnhearfield.com

5. BHEL

6. askguru.com

7. raids.com

8. SMVDU (COURCE TCSN)