Radar

I E T

MAHATMA JYOTIBA PHULE

ROHILKHAND UNIVERSITY BAREILLY

A TRAINING REPORT ON RADAR

SUBMITTED BY:-

RAKESH KUMAR YADAV

08EC34

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PREFACEWith the ongoing revolution in electronics and communication where

innovations are taking place at the blink of eye, it is impossible to keep

pace with the emerging trends.

Excellence is an attitude that the whole of the human race is born with. It

is the environment that makes sure that whether the result of this attitude

is visible or otherwise. A well planned, properly executed and evaluated

industrial training helps a lot in culcating a professional attitude. It

provides a linkage between a student and industry to develop an

awareness of industrial approach to

problem solving, based on a broad understanding of process and mode of

operation of organization.

During this period, the student gets the real experience for working in the

industry environment. Most of the theoretical knowledge that has been

gained during the course of their studies is put to test here. Apart from

this the student gets an opportunity to learn the latest technology, which

immensely helps in them in building their career.

We had the opportunity to have a real experience on many ventures,

which increased our sphere of knowledge to great extent. We got a

chance to learn many new technologies and also interfaced too many

instruments. And all this credit goes to organization Bharat Electronics

Limited.

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ACKOWLEDGEMENT I wish to express my sincere thanks to the management of Bharat Electronics Limited

(BEL), Bharat Nagar, Ghaziabad including the Head of the Human Resource

Development Department Mrs Vanita Bhandari (DGM, H.R.D.) for providing me

an opportunity to receive training in this esteemed company. I am deeply indebted

to Mr. Manager, Radar

Division (TESTING) for sparing his most precious time in providing guidance to me

in training. Without his wise counsel, inestimable encouragement, it would have been

difficult for me to have knowledge of the functioning of various types of electronics

equipment particularly radars. Gratitude is also due to him for his constant guidance

and direction in writing this piece of work.

Special thanks to , Deputy Manager for her

valuable guidance, help and co-operation.

It is a great pleasure to express my heart full thanks to staff of BEL who helped me

directly or indirectly throughout the successful completion of my training. There is no

substitute to ‘Team Work’; this is one of the lessons I learnt during my training in

Bharat Electronics Limited

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CONTENTS.NO. Title Page No 1 Certificate 5 2 Declaration 6 3 BEL Introduction 7 4 Product ranges 11 5 BEL Ghaziabad Unit 146 Rotation program 21 7 Test equipment & Automation 21 8 Magnetics 23 9 Microwave lab 2510 PCB Fabrication 26 11 Quality control 29 12 Introduction to radar 33 13 Types of radar 37 14 Working of simple radar 40 15 Application of radar 43 16 SRE 45 17 Conclusion 55

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CERTIFICATE

TO WHOM SO EVER IT MAY CONCERN

This is to certify that RAKESH KUMAR YADAV, the students of

B.tech Electronics and Communication Engineering from MAHATMA

JYOTIBA PHULE ROHILKHAND UNIVERSITY BAREILLY has

undergone an industrial training on project titled ‘Study of RECEIVER

of SRE’ at BHARAT ELECTRONICS LIMITED, GHAZIABAD

w.e.f 21 JUNE 2011 to 30 JULY 2011 under the guidance of

, Deputy Manager.

They worked diligently and made valuable contribution during this

period. All their works are genuine and original.

Mr Mr

( MANAGER) (DEPUTY MANAGER)

(PROJECT GUIDE )

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DECLARATION

I hereby declare that the project work entitled “UPT RECORD FORM” is an authentic work carried by me at Bharat Electronics Limited, Ghaziabad , under worthy and esteemed guidance of Mr. (DEPUTY ENGINEER) at Bharat Electronics Limited , Ghazi bad.

This work has not been submitted to any other

institution or university for award of any degree

RAKESH KUMAR YADAV

UPT 1148/B.Tech/2011

Roll No. 08ec34

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BHARAT ELECTRONICS LIMITED

INTRODUCTION

India, as a country, has been very lucky with regard to the introduction of telecom

products. The first telegraph link was commissioned between Calcutta and Diamond

Harbor in the year 1852, which was invented in 1876. First wireless communication

equipment were introduced in Indian Army in the year 1909 with the discovery of

Radio waves in 1887 by Hertz and demonstration of first wireless link in the year

1905 by Marconi and Vacuum Tube in 1906. Setting up of radio station for broadcast

and other telecom facilities almost immediately after their commercial introduction

abroad followed this. After independence of India in 1947 and adoption of its

constitution in 1950, the government was seized with the plans to lay the foundations

of a strong, self-sufficient modern India. On the industrial front, Industrial Policy

Resolution (IPR) was announced in the year 1952. It was recognized that in certain

core sectors infrastructure facilities require huge investments, which cannot be met by

private sector and as such the idea of Public Sector Enterprises (PSR) was mooted.

With telecom and electronics recognized among the core sectors, Indian Telephone

Industry, now renamed as ITI Limited, was formed in 1953 to undertake local

manufacture of telephone equipment, which were of electro-mechanical nature at that

stage. Hindustan Cable Limited was also started to take care of telecom cables.

Bharat Electronics Limited (BEL) was established in 1954 as a public Sector

Enterprise under the administrative control of Ministry of Defence as the

fountainhead to manufacture and supply electronics components and equipment.

BEL, with a noteworthy history of pioneering achievements, has met the requirement

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of state-of-art professional electronic equipment for Defence, broadcasting, civil

Defence and telecommunications as well as the component requirement of

entertainment and medical X-ray industry. Over the years, BEL has grown to a multi-

product, multi-unit, and technology driven company with track record of a profit

earning PSU.

The company has a unique position in India of having dealt with all the

generations of electronic component and equipment. Having started with a HF

receiver in collaboration with T-CSF of France, the company’s equipment designs

have had a long voyage through the hybrid, solid-state discrete component to the state

of art integrated circuit technology. In the component arena also, the company

established its own electron value manufacturing facility. It moved on to

semiconductors with the manufacture of germanium and silicon devices and then to

the manufacture of Integrated circuits. To keep in pace with the component and

technology, its manufacturing and products assurance facilities have also undergone

sea change. The design groups have CADD facility, the manufacturing has CNC

machines and a Mass Manufacture Facility. QC checks are preformed with multi-

dimensional profile measurement machines, Automatic testing machines,

environmental labs to check extreme weather and other operational conditions. All

these facilities have been established to meet the stringent requirements of MIL grade

systems.

Today BEL’s infrastructure is spread over nine locations with 29

production divisions having ISO-9001/9002 accreditation. Product mix of the

company are spread over the entire Electro-magnetic (EM) sp 3ectrum ranging from

tiny audio frequency semiconductor to huge radar systems and X-ray tubes on the

upper edge of the spectrum. Its manufacturing units have special focus towards the

products ranges like Defence Communication, Rader’s, Optical & Opto-electronics,

Telecommunication, sound and Vision Broadcasting, Electronic Components, etc.

Besides manufacturing and supply of a wide variety of products, BEL offers a

variety of services like Telecom and Rader Systems Consultancy, Contract

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Manufacturing, Calibration of Test & Measuring Instruments, etc. At the moment, the

company is installing MSSR radar at important airports under the modernization of

airports plan of National Airport Authority (NAA).

BEL has nurtured and built a strong in-house R&D base by absorbing

technologies from more than 50 leading companies worldwide and DRDO Labs for a

wide range of products. A team of more than 800 engineers is working in R&D. Each

unit has its own R&D Division to bring out new products to the production lines.

Central Research Laboratory (CRL) at Bangalore and Ghaziabad works as

independent agency to undertake contemporary design work on state-of-art and

futuristic technologies. About 70% of BEL’s products are of in-house design.

BEL was among the first Indian companies to manufacture computer parts

and peripherals under arrangement with International Computers India Limited

(ICIL) in 1970s. BEL assembled a limited number of 1901 systems under the

arrangement with ICIL. However, following Government’s decision to restrict the

computer manufacture to ECIL, BEL could not progress in its computer

manufacturing plans. As many of its equipment were microprocessor based, the

company,

Continued to develop computers based application, both hardware and software. Most

of its software requirements are in real time. EMCCA, software intensive navel ships

control and command system is probably one of the first projects of its nature in India

and Asia.

BEL has won a number of national and international awards for Import

Substitution, Productivity, Quality, Safety, Standardization etc. BEL was ranked No.

1 in the field of Electronics and 46th overall among the top 1000 private and public

sector undertakings in India by the Business Standard in its special supplement “The

BS 1000 (1997-98)”. BEL was listed 3rd among the Mini Ratanas (Category II) by

the Government of India, 49th among Asia’s top 100 worldwide Defence Companies

by the Defence News, USA.

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CORPORATE MOTTO , MISSION

AND OBJECTIVES:The passionate pursuit of excellence at BEL is reflected in a reputation with its

customers that can be described in its motto, mission and objectives:

CORPORATE MOTTO

“ Quality, Technology and Innovation .”

CORPORATE MISSION

To be the market leader in Defence Electronics and in other chosen fields and

products.

CORPORATE OBJECTIVES

To become a customer-driven company supplying quality products at competitive

prices at the expected time and providing excellent customer support.

To achieve growth in the operations commensurate with the growth of

professional electronics industry in the country.

To generate internal resources for financing the investments required for

modernization, expansion and growth for ensuring a fair return to the investor.

In order to meet the nation’s strategic needs, to strive for self-reliance by

indigenization of materials and components.

To retain the technological leadership of the company in Defence and other

chosen fields of electronics through in-house research and development as well as

through Collaboration/Co-operation with Defence/National Research

Laboratories, International Companies, Universities and Academic Institutions.

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To progressively increase overseas sales of its products and services.

To create an organizational culture which encourages members of the

organization to realize their full potential through continuous learning on the

job and through other HRD initiatives.

CUSTOMER PROFILE & BEL

PRODUCT RANGE

Equipments:

DEFENCE

ARMY Tactical and Strategic Communication Equipment and Systems, Secrecy Equipment, Digital Switches, Battlefield Surveillance Radar, Air Defence and Fire Control Radar, Opto-Electronic Instruments, Tank Fire Control Systems, Stabilizer Systems, Stimulators and Trainers.

NAVY Navigational, Surveillance, Fire Control Radar, IFF, SONAR Systems, Torpedo Decoys, Display Systems, EW Systems, Simulators, Communication Equipment and Systems.

AIR FORCE Surveillance and Tracking Raiders, Communication Equipment and Systems, IFF and EW Systems.

NON-DEFENCE

PARA-MILITARY Communication Equipment and Systems.

SPACE DEPARTMENT Precision Tracking Radar, Ground Electronics, Flight and On-board Sub-Systems.

ALL INDIA RADIO MW, SW &FM Transmitters.

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DOORDARSHAN

(TV NETWORK)

Low, Medium and High Power Transmitters, Studio Equipment, OB Vans, Cameras, Antennae, Mobile and Transportable Satellite Uplinks.

NCERT TV Studios on turnkey Basis for Educational Programs.

DEPARTMENT OF TELECOMMUNICATION

Transmission Equipment (Microwave and UHF) and PCM Multiplex, Rural and Main Automatic Exchanges, Flyaway Satellite Terminals, Solar Panels for Rural Exchanges.

VIDESH SANCHAR NIGAMAND OTHER CORPORATE BODIES

MCPC VSAT, SCPC VSAT, Flyaway Earth Stations. Hub Stations, Up/Down Converters, LNA Modems.

CIVIL AVIATION Airport Surveillance Radar, Secondary Surveillance Radar.

METEOROLOGICAL DEPARTMENT

Cyclone Warning and Multipurpose Meteorological Radar.

POWER SECTOR Satellite Communication Equipment.

OIL INDUSTRY Communication Systems, Radar.

FOREST DEPARTMENTS, IRRIGATION & ELECTRICITY BOARDS

Communication Systems.

MEDICAL & HEALTH CARE

Clinical and Surgical Microscope with Zoom, Linear Accelerators.

RAILWAYS Communication Equipment for Metros, Microwave Radio Relays and Digital Microwave Radio Relays.

Components:

DEFENCE Transmitting Tubes, Microwave Tubes, Lasers, Batteries, Semiconductors-Discrete, Hybrid and Circuits.

NON-DEFENCE

All India Radio, Doordarshan

(TV Network),

Transmitting Tubes, Microwave Tubes, and Vacuum Tubes.

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Telecommunications and Civil Industries

Entertainment Industry B/W TV Tubes, Silicon Transistors, Integrated Circuits, Bipolar and CMOS, Piezo-Electric Crystals, Ceramic Capacitors and SAW Filters.

Telephone Industry Integrated Circuits, Crystals.

Switching Industry Vacuum Interrupters.

Instrumentation Industry Liquid Crystal Displays.

Medical & Health Care X-ray Tubes.

System/Networks:

Identity Card Systems Software, Office Automation Software, LCD On-line Public

Information Display Systems and Communication Networks / VSAT Networks.

FINANCIAL PERFORMANCEBEL has a unique history of profit making Public Sector Enterprise right from its

inception. There have been events of decrease in turnover and profit after Tax due to

reasons beyond reasonable control of the company. But the company’s strength lies in

its capability to combat the threats, for example US Embargo on exports to BEL.

BEL hopes to generate 25 per cent increase in turnover with a 15 per cent rise

in net profit in the current fiscal year over the previous. Corrective measures against

western sanctions have been undertaken, which are likely to translate into higher

turnover and profitability. The company is putting all efforts to minimize the effect of

the restrictions by early establishments of alternative arrangements. The Defence

Research Laboratories and Academic Institutions are also being persuaded with for

indigenisation of certain special category of devices and components. The company is

also opening an office in Singapore to procure components from Asian markets. Thus

in the long run the restrictions will prove as blessings resulting in self-dependence

and better profit margins.

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Also several R&D projects with long gestation periods will go into

commercial production during the current fiscal.

BEL GHAZIABAD UNIT

Formation

In the mid 60’s, while reviewing the Defence requirement of the

country, the government focused its attention to strengthen the Air Defence system, in

particular the ground electronics system support, for the air Defence network. This

led to the formulation of a very major plan for an integrated Air Defence Ground

Environment System known as the plan ADGES with Prime Minister as the presiding

officer of the apex review committee .At about the same time, Public attention was

focused on the report of the Bhabha committee on the development and production of

electronic equipment. The ministry of Defence immediately realized the need to

establish production capacity for meeting the electronic equipment requirements for

its plan ADGES.

BEL was then inserted with the task of meeting the development and

production requirement for the plan ADGES and in view of the importance of the

project it was decided to create additional capacity at a second unit of the company.

In December 1970 the Govt. sanctioned an additional unit for BEL. In 1971,

the industrial license for manufacture of radar and microwave equipment was

obtained, 1972 saw the commencement of construction activities and production was

launched in 1974.

Over the years, the unit has successfully manufactured a wide variety of

equipment needed for Defence and civil use. It has also installed and commissioned a

large number of systems on turnkey basis. The unit enjoys a unique status as

manufacture of IFF systems needed to match a variety of primary raiders. More than

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30 versions of IFF’s have already been supplied traveling the path from vacuum

technology to solid-state to latest Microwave Component based system.

PRODUCT RANGES

The product ranges today of the company are:

RADAR SYSTEMS

3-Dimensional High Power Static and Mobile Radar for the Air Force.

Low Flying Detection Radar for both the Army and the Air force.

Tactical Control Radar System for the Army.

Battlefield Surveillance Rader for the Army.

IFF Mk-X Radar systems for the Defence and export.

ASR/MSSR systems for Civil Aviation.

Radar & allied systems Data Processing Systems.

COMMUNICATIONS

Digital Static Tropo scatter Communication Systems for the Air Force.

Digital Mobile Tropo scatter communication System for the Air Force and

Army.

VHF, UHF & Microwave Communication Equipment.

Bulk Encryption Equipment.

Turnkey communication Systems Projects for Defence & civil users.

Static and Mobile Satellite Communication Systems for Defence.

Telemetry /Tele-control Systems.

ANTENNA

Antennae for Radar, Terrestrial & Satellite Communication Systems.

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Antennae for TV Satellite Receive and Broadcast applications.

Antennae for Line-of-sight Microwave Communication Systems.

MICROWAVE COMPONENT

Active Microwave components like LNAs, Synthesizer, Receivers etc.

Passive Microwave components like Double Balanced Mixers,etc.

Most of these products and systems are the result of a harmonious

combination of technology absorbed under ToT from abroad, Defence R&D

Laboratories and BEL’s own design and development efforts.

THE ORGANIZATION

The operations at BEL Ghaziabad are headed by General Manager with

Additional / Deputy General Manager heading various divisions as follows:

1. DESIGN & ENGINEERING DIVISIONS

Development and Engineering-R

Development and Engineering-C

Development and Engineering-Antenna.

2. EQUIPMENT MANUFACTURING DIVISIONS

Radar

Communication

Antenna

Systems

Microwave Components

3. SUPPORT DIVISIONS

Material management

Marketing & Customer Co-ordination

Quality Assurance & Torque

Central Services

PCB & Magnetics

Information Systems

Finance & Accounts

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Personnel & Administration

Management Services.

DESIGN & ENGINEERING

The pace of development and technological obsolescence in their field of

electronics necessitates a strong Research and Development base. This is more

important on the area of Defence Electronics. BEL Ghaziabad has since its inception

laid a heavy emphasis on indigenous research and development. About 70% its of

manufacture today relate to items developed in-house. For the development and

production of the Mobile Torpo scatter System and the equipment, BEL was awarded

the Gold Shield for Import Substitution.

Design facilities are also constantly being modernized and substantial

computer-aided design facilities are being introduced including installation of mini-

and microcomputers and dedicated design application. About 170 graduate and post-

graduate engineers are working on research and indication of the importance R&D

has in BEL’s growth.

Three Design and Engineering group are product based viz. Communication, Radar

and Antenna. These divisions are further divided into different departments to look

after products of a particular nature. each of them has a drawing office attached to

them, which are equipped with latest drafting and engineering software. The PCB

layout and PCB master making is done at CADD Center. A central Records &

Printing section takes care of the preserving the engineering documents and

distribution thereof. Most of the engineering documents are available online.

EQUIPMENT MANUFACTURING DIVISIONS

As a supplier of equipment to the Defence services and professional users,

strict adherence to specifications and tolerances, has to be in-built into the design and

manufacturing process. For this BEL Ghaziabad has well defined standards and

processes for as well as manufacturing and testing activities. Activities are divided

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into various departments like Production Control, Works Assembly, and QC

WORKS. The manufacture and control of production is through a central systems,

BELMAC, BEL’s own homegrown ERP system.

Apart from conventional machines, BEL Ghaziabad has been equipped with

several repeat occurrences and increased throughput. A separate NC programming

cell has been set up to develop the programs for execution on the CNC machines.

MICROWAVE COMPONENT GROUP

Frequencies greater than 1 GHz are termed as Microwaves. Microwaves Integrated

Circuits (MIC) used extensively in the production of subsystems for Radar and

Communication equipment constitutes a very vital part of the technology for these

systems and is generally imported. Owing to the crucial and building block nature of

the technology involved, BEL is currently setting up a modern MIC manufacturing

facility at a planned expenditure of Rs. 2 crore. When in full operation, this facility

will be the main center for the MIC requirements of all the units of the company.

The manufacturing facilities of hybrid microwave components available at

BEL, Ghaziabad includes facility for preparation of substrates, assembly of

miniaturized component viz. directional couplers, low noise amplifiers, phase shiftier,

synthesizers etc. involves scalar as well as vector measurements. For this state of the

network analysis are used.

MATERIAL MANAGEMENT

Material Management division is responsible for procurement, storage

handling, issue of purchased parts as well as raw materials required to manufacture

various equipment and spares. It also takes care of disposal of unused or waste

material.

The division is divided into purchase, Component store, Raw material store,

Chemical store, Custom Clearance Cell, Inventory management & disposal.

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MARKETING AND CUSTOMER CO-ORDINATION

This division is responsible foe acquisition and execution of customer orders

and customer services. Marketing department looks after order acquisition.

Commercial department looks after order execution. Shipping takes care of packing

and dispatch of material to customer.

QUALITY ASSURANCE & TORQUE

In the area of professional Defence electronics, the importance of Quality and

Reliability is of utmost importance. BEL has therefore established stringent processes

and modern facilities and systems to ensure product quality- from the raw material to

the finished product. IGQA, Environmental Labs, Test Equipment Support and QA

departments are grouped under this division.

All material for consumption in the factory passes through stringent inward

goods screening in IGQA department before being accepted for use.

Subsequent to manufacture and inspection, the end product is again put

through a rigorous cycle of performance and environmental checks in Environmental

Labs.

The testing, calibration and repair facility of test Instruments used in the

factory is under the control of Test Equipment Support. All the instruments come to

this department for periodic calibration.

Quality Assurance department facilitates ISO 9000 certification of various

divisions. All production divisions of BEL Ghaziabad are ISO9000 certified. The

microwave division is ISO9001 certified whereas the remaining three division viz.

Radar, Communication and Antennae are also ISO9002 certified.

CENTRAL SERVICES

Central services Division looks after plant and maintenance of the estate

including electrical distribution, captive power generation, telephones, transport etc.

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PCB FABRICATION & MAGNETICS

PCB Fabrication, Coil and Magnetics, Technical Literature, Printing Press and

Finished Goods are the areas under this division.

Single sided PCB blanks- having circuit pattern on one side of the board and

double sided- having circuit pattern on both sides of the board are manufactured in

house. However, Multi-layered PCBs, having many layers of circuit, are obtained

from other sources.

Magnetic department makes all type of transformers & coils that are used in

different equipment. Coils and transformers are manufactured as per various

specifications such as number of layers, number of turns, types of windings, gap in

core, dielectric strength, insulation between layers, electrical parameters, impedance

etc. laid down in the documents released by the D&E department.

INFORMATION SYSTEMS

IS Department is responsible for BEL’s own home grown manufacturing and

control systems called BELMAC.it comprises of almost all modules a modern ERP

systems but is Host and dumb terminal based.

FINANCE & ACCOUNTS

The F&A division is divided into Budget & Compilation, Cost and Material

Accounts, Bills Payable, Bill Receivable, Payrolls, Provident Fund, Cash Sections.

PERSONAL & ADMINISTRATION DEPARTMENT

There are at present about 2300 employees at BEL Ghaziabad, of which more

than 400 are graduate and postgraduate engineers

ROTATION PROGRAM

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Under this students are introduced to the company by putting them under a rotation

program to various departments. The several departments where I had gone under my

rotational program are:

Test Equipment and Automation

P.C.B. Fabrication

Quality Control Works-Radar

Work Assembly- Communication

Magnetic

Microwave lab

Rotation period was to give us a brief insight of the company’s functioning and

knowledge of the various departments. A brief idea of the jobs done at the particular

departments was given. The cooperative staff at the various departments made the

learning process very interesting , which allowed me to know about the company in a

very short time.

TEST EQUIPMENT AND AUTOMATION :

This department deals with the various instruments used in BEL. There are 300

equipments and they are of 16 types.

Examples of some test equipments are:

Oscilloscope(CRO)

Multimeter

Signal Analyzer

Logical Pulsar

Counter

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Function Generator etc.

Mainly the calibration of instruments is carried out here. They are compared with the standard of National Physical Laboratory (NPL). So, it is said to be one set down to NPL. As every instrument has a calibration period after which the accuracy of the instrument falls from the required standards. So if any of the instruments is not working properly, it is being sent here for its correct calibration. To calibrate instruments software techniques are used which includes the program written in any suitable programming language. So it is not the calibration but programming that takes time .For any industry to get its instrument calibrated by NPL is very costly, so it is the basic need for every industry to have its own calibration unit if it can afford it.

Test equipment and automation lab mainly deals with the equipment that is used

for testing and calibration .The section calibrates and maintains the measuring

instruments mainly used for Defense purpose.

A calibration is basically testing of equipment with a standard parameter. It is

done with the help of standard equipment should be of some make, model and type.

The national physical laboratory (NPL) ,New Delhi provides the standard values

yearly. BEL follows International Standard Organization (ISO) standard. The test

equipments are

calibrated either half yearly or yearly.

After testing different tags are labeled on the equipment according to the

observations.

Green –O.K , Perfect

Yellow – Satisfactory but some trouble is present.

Red – Can’t be used, should be disposed off.

The standard for QC, which are followed by BEL are:

WS 102

WS 104

PS 520

PS 809

PS 811

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PS 369

Where, WS = Workmanship & PS = Process Standard

After the inspection of cables, PCB’s and other things the defect found are given

in following codes.

A --- Physical and Mechanical defects.

B --- Wrong Writing

C --- Wrong Component / Polarity

D --- Wrong Component / Mounting

E --- Bad Workmanship/ Finish

F --- Bad Soldering

G --- Alignment Problem

H --- Stenciling

I --- Others (Specify)

J --- Design & Development

After finding the defect, the equipment is sent to responsible department

which is rectified there.

MAGNETICSIn this department different types of transformers and coils are manufactured ,

which are used in the various defense equipments i.e. radar , communication

equipments.

This department basically consists of three sections:

1.) PRODUCTION CONTROL :- Basic function of production control is to

plan the production of transformer and coils as per the requirement of

respective division (Radar and Communication). This department divided into two

groups:

(a) Planning and (b) Planning store.

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2.) WORKS (PRODUCTION) :- Production of transformers and coils are being

carried out by the works departments.

3.) QUALITY CONTROL :- After manufacturing the transformer/coils the item

is offered to the inspection department to check the electrical parameters(DCR ,

No load current , full load current , dielectric strength , inductance , insulation

resistance and mechanical dimension as mentioned in the GA drawing of the

product.

The D&E department provides all the information about manufacturing a coil

and the transformer.

The various types of transformers are as follows :

i) Air cored transformers

ii) Oil filled transformers

iii) Moulding type transformers

iv) P.C.B Mounting transformers :-

(a) Impedance matching transformers

(b) RF transformers

(c) IF transformers

The various types of cores are as follows :

i) E type

ii) C type

iii) Lamination

iv) Ferrite core

v) Toroidal core

Steps involved in the process of manufacturing of transformer/coils:

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a.) Preparation of former : Former is made of plastic bakelite comprising a

male and female plates assembled and glued alternately to form a hollow

rectangular box on which winding is done.

b.) Winding : It is done with different material and thickness of wire. The

winding has specified number of layers with each layer’s having a

specified number of turns. The distance between the two turns should be

maintained constantly that is there should be no overlapping. The plasatic

layer is inserted between two consecutive layers.

The various types of windings are as follows :

i) Layer Winding

ii) Wave Winding

iii) Bank Winding

c.) Insulation : For inter-winding and inter layer , various types of insulation

sheets viz. Craft paper , paper , leather , oil paper , polyester film are being

used.

d.) Protection : To protect the transformer from the external hazards , moisture ,

dust and to provide high insulation resistance , they are impregnated.

MICROWAVE LABORATORY

Microwave lab deals with very high frequency measurements or very short

wavelength measurements. The testing of microwave components is done

with the help of various radio and communication devices. Phase and

magnitude measurements are done in this section. Power measurements are

done for microwave components because current and voltage are very high at

such frequencies.

Different type of waveguides is tested in this department like rectangular

waveguides, circular waveguides. These waveguides can be used to transmit

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TE mode or TM mode. This depends on the users requirements. A good

waveguide should have fewer loses and its walls should be perfect conductors.

In rectangular waveguide there is min. distortion. Circular waveguides are

used where the antenna is rotating. The power measurements being done in

microwave lab are in terms of S- parameters. Mainly the testing is done on

coupler and isolators and parameters are tested here.

There are two methods of testing:

1. Acceptance Test Procedure(ATP)

2. Production Test Procedure(PTP)

Drawing of various equipments that are to be tested is obtained and testing is

performed on manufactured part. In the antenna section as well as SOHNA

site various parameters such as gain ,bandwidth ,VSWR , phase ,return loss,

reflection etc. are checked. The instruments used for this purpose are as

follow:

1. Filters

2. Isolators

3. Reflectors

4. Network Analyzers

5. Spectrum Analyzers

6. Amplifiers and Accessories

P.C.B. FABRICATIONP.C.B. stands for Printed Circuits Board. It’s an integral part of the Electronics equipment as well as all the components are mounted on it. It Consists of the fiberglass sheet having a layer of copper on both sides.

TYPES OF PCBs1. Single Sided Board : Circuits on one side.

2. Double Sided Board : Circuit on Both side.

3. Muti-layer Board : Several layers are interconnected

through hole metalization.

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Raw material for PCB’s

Most common raw material used for manufacturing of PCBs is copper cladded glass epoxy resin sheet. The thickness of the sheet may vary as 1.2, 2.4 and 3.2mm and the standard size of the board is 610mm to 675mm.

Operation in process

Following steps are there for PCB manufacturing :-

CNC Drilling

Drill Location

Through Hole Plating

Clean Scrub and Laminate

Photo Print

Develop

Cu electroplate

Tin electroplate

Strip

Etching and cleaning

Tin Stripping

Gold plating

Liquid Photo Imageable Solder Masking (LPISM)

Photo print

Develop

Thermal Baking

Hot Air leaving

Non Plated Hole Drilling

Reverse Marking

Sharing & Routing

Debarring & Packing

P.C.B. is a non-conducting board on which a conductive board is made. The base material, which is used for PCB plate are Glass Epoxy, Bakelite and Teflon etc.

27

Procedure for through hole metallization

Loading-Cleaner-Water Rinse-Spray Water-Rinse-Mild Etch-Spray Water-Rinse-Hydrochloric Acid-Actuator-Water Rinse-Spray Water-Rinse-Accelerator Dip-Spray Water- Rinse- Electrolyses Copper-Plating-Plating- Spray water-Rinse-Anti Tarnish Dip-Hot Air Drying- Unloading.

After through hole metallization, photo tool generation is done which is followed by photo printing. In this the PCB is kept b/w two blue sheets and the ckt. is printed on it. A negative and a positive of a ckt. are developed. To identify b/w the negative and positive, following observation is done. If the ckt. is black and the rest of the sheet is white, it is positive otherwise negative.

Next, pattern plating is done. The procedure for pattern plating follows :

Loading- Cleaner- Water rings- Mild etch- Spray- Water Rinse-Electrolytic- Copper plating- Water rinse- Sulfuric acid-Tin plating- Water rinse- Antitarnic dip- Hot air dry- Unloading.

To give strength to the wires so that they can not break. This is done before molding. Varnishing is done as anti fungus prevention for against environmental hazard.

After completion of manufacturing proceeds it is sent for testing. This is followed by resist striping and copper etching. The unwanted copper i.e. off the tracks is etched by any of the following chemicals. After this, tin is stripped out from the tracks.

After this solder marking is done. Solder marking is done to mark the tracks to get oxidized & finally etch. To prevent the copper from getting etched & making the whole circuit functionally done.

There are three types of solder marking done in BEL :

Wet solder mask: Due to some demerits this method is totally ruled out. The demerit was

non- alignment, which was due to wrong method applied or wrong machine.

Dry pin solder mask : Due to wastage of films about 30% this method is also not used now.

Liquid photo imaginable solder mask (LPISM): In this first presoaking is at 80 degree Celsius for 10 to 20 minutes. Next, screen preparation is done. The board is covered by a silk cloth whose mesh is T-48. The angle to tilt of the board is 15 degree to 22.5 degree.

The next is ink preparation:

Ink + Hardener

28

71 % : 29 %

(150 gms.) : (300gms.)

+

Butyrate solo solve 50gms/kg.

Ink preparation-It uses :-

Ink-----100gm

Catalyst----10% of total weight

Reducer-----10% of total weight

The catalyst is used as binder and prevents the following, while reducer is used as thinner. The three things are then fully mixed.

For wash out, following procedure takes place.

Water-Lactic acid-Water-Bleaching power-Water-caustic Soda-Water-Air dry-TCE.

After wash out, final baking for one hour at the temt. of 20degree C is done. After this shearing or routing is done which is followed by debarring and packing.

QUALITY CONTROL

(WORK ASSEMBLY)According to some laid down standards, the quality control department ensures the

quality of the product. The raw materials and components etc. purchased and

inspected according to the specifications by IG department. Similarly QC work

department inspects all the items manufactured in the factory. The fabrication

department checks all the fabricated parts and ensures that these are made according

29

to the part drawing, painting , plating and stenciling etc are done as per BEL

standards.

The assembly inspection departments inspects all the assembled parts such as PCB ,

cable assembly ,cable form , modules , racks and shelters as per latest documents and

BEL standards .

The mistakes in the PCB can be categorized as:

1. D & E mistakes

2. Shop mistakes

3. Inspection mistakes

The process card is attached to each PCB under inspection. Any error in the PC is

entered in the process card by certain code specified for each error or defect.

After a mistake is detected following actions are taken:

1. Observation is made.

2. Object code is given.

3. Division code is given.

4. Change code is prepared.

5. Recommendation action is taken

WORK ASSEMBLY

This department plays an important role in the production. Its main function is to

assemble various components, equipments and instruments in a particular procedure.

It has been broadly classified as:

30

WORK ASSEMBLY RADAR e.g. INDRA –II, REPORTER.

WORK ASSEMBLY COMMUNICATION e.g EMCCA, MSSR, MFC.

EMCCA:EQUIPMENT MODULAR FOR COMMAND CONTROL

APPLICATION.

MSSR: MONOPULSE SECONDARY SURVEILLANCE RADAR.

MFC: MULTI FUNCTIONAL CONSOLE.

The stepwise procedure followed by work assembly department is:

1. Preparation of part list that is to be assembled.

2. Preparation of general assembly.

3. Schematic diagram to depict all connections to be made and brief idea

about all components.

4. Writing lists of all components.

In work assembly following things are done :

M aterial Receive :

Preparation- This is done before mounting and under takes two procedures.

Tinning- The resistors ,capacitors and other components are tinned with the help of

tinned lead solution .The wire coming out from the components is of copper and it is

tinned nicely by applying flux on it so that it does not tarnished and soldering

becomes easy.

Bending- Preparation is done by getting the entire documents , part list drawing and

bringing all the components before doing the work.

Mounting- It means soldering the components of the PCB plate with the help of

soldering tools. The soldering irons are generally of 25 W and are of variable

temperature, one of the wires of the component is soldered so that they don’t move

from their respective places on the PCB plate. On the other hand of the component is

also adjusted so that the PCB does not burn.

31

Wave Soldering- This is done in a machine and solder stick on the entire path, which

are tinned.

Touch Up- This is done by hand after the finishing is done.

Cleaning:

Inspection- This comes under quality work.

Heat Ageing- This is done in environmental lab at temperature of 40 degree C for 4

hrs and three cycles.

Testing:

Lacquering- This is only done on components which are not variable.

Storing- After this variable components are sleeved with Teflon. Before Lacquering

mounted plate is cleaned with isopropyl alcohol. The product is then sent to store.

32

33

RADAR(RADIO DETECTION AND RANGING)

INTRODUCTION

Radar is an electromagnetic system for the detection and location of reflecting objects

such as aircrafts, ships, spacecraft, vehicles, peoples and the natural environment. It

operates by radiating energy into space and detecting the reflected echo signal from

an object, or target. The reflected energy to the radar not only indicates the presence

of a target, but by comparing the received echo signal with the signal that was

transmitted, its location can be determined along with other target related

information. Radar can perform its function at long or short distances and under

conditions impervious to optical and infrared sensors. It can operate in darkness,

haze, fog, rain and snow. Its ability to measure the distance with high accuracy and in

all weather is one of its most important attributes. Although most of the radar units

use microwave frequencies, the principle of radar is not confine to any particular

frequency range. There are some radar units that operate on frequencies well below

100 MHz and others that operate in the infra-red range and above.

RADAR DEVELOPMENT

Although the development of radar as a full-fledged technology did not occur until

World War-II, the basic principle of radar detection is almost as old as the subject of

electromagnetism itself. Heinrich Hertz, in 1886, experimentally tested the theories of

Maxwell and demonstrated the similarity between radio and light waves. Hertz

showed that radio waves could be reflected by metallic and dielectric bodies. It is

interesting to know that although Hertz’s experiments were performed with relatively

short wavelength radiation (66 cm), later work in radio engineering was almost

entirely at longer wavelengths. The shorter wavelengths were not actively used to any

extent until the late thirties. One of the biggest advocators of radar technology was

Robert Watson-Watt, a British scientist.

34

Several inventors, scientists, and engineers contributed to the development of radar.

The use of radio waves to detect "the presence of distant metallic objects via radio

waves" was first implemented in 1904 by Christian Hülsmeyer, who demonstrated the

feasibility of detecting the presence of ships in dense fog and received a patent for

radar as Reichspatent Nr. 165546. Another of the first working models was produced

by Hungarian Zoltán Bay in 1936 at the Tungsram laboratory.

While radar development was pushed because of wartime concerns, the idea first

came about as an anti-collision system. After the Titanic ran into an iceberg and sank

in 1912, people were interested in ways to make such happenings avoidable.

The term RADAR was coined in 1941 as an acronym for Radio Detection and

Ranging. The name reflects the importance placed by the workers in this field on the

need for a device to detect the presence of a target and to measure its range. This

acronym of American origin replaced the previously used British abbreviation RDF

(Radio Direction Finding).

Although modern radar can extract more information from a target’s echo

signal than its range, the measurement of range is still one of its most important

functions. There are no competitive techniques that can accurately measure long

ranges in both clear and adverse weather as well as can radar.

BASIC PRINCIPLE

An elementary form of radar consists of a transmitting antenna emitting

electromagnetic radiation generated by an oscillator of some sort, a receiving antenna,

and an energy-detecting device, or receiver. A transmitter generates an

electromagnetic signal (such as a short pulse of sine wave) that is radiated into space

by an antenna. A portion of the transmitted energy is intercepted by the target and

reradiated in many directions. The reradiation directed back towards the radar is

collected by the radar antenna, which delivers it to a receiver. There it is processed to

detect the presence of the target and determine its location. A single antenna is

usually used on a time-shared basis for both transmitting and receiving when the

35

radar waveform is a repetitive series of pulses. The range, or distance, to a target is

found by measuring the time it takes for the radar signal to travel to the target and

return back to the radar. (Radar engineers use the term range to mean distance) The

target’s location in angle can be found from the direction the narrow -beamwidth

radar antenna points when the received echo signal is of maximum amplitude. If the

target is in motion, there is a shift in the frequency of the echo signal due to the

Doppler effect. This frequency shift is proportional to the velocity of the target

relative to the radar (also called the radial velocity). The Doppler frequency shift is

widely used in radar as the basis for separating desired moving targets from fixed

(unwanted) “clutter’ echoes reflected from the natural environment such as land, sea,

or rain. Radar can also provide information about the nature of the target being

observed.

ECHO AND DOPPLER SHIFT

Echo is something you experience all the time. If you shout into a well or a canyon,

the echo comes back a moment later. The echo occurs because some of the sound

waves in your shout reflect off of a surface (either the water at the bottom of the well

or the canyon wall on the far side) and travel back to your ears. The length of time

between the moments you shout and the distance between you and the surface that

creates the echo determines the moment that you hear the echo.

Doppler shift is also common. You probably experience it daily (often

without realizing it). Doppler shift occurs when sound is generated by, or reflected off

of, a moving object. Doppler shift in the extreme creates sonic booms (see below).

Here's how to understand Doppler shift (you may also want to try this experiment in

an empty parking lot). Let's say there is a car coming toward you at 60 miles per hour

(mph) and its horn is blaring. You will hear the horn playing one "note" as the car

approaches, but when the car passes you the sound of the horn will suddenly shift to a

lower note. It's the same horn making the same sound the whole time. The change

you hear is caused by Doppler shift.

36

TYPES OF RADAR

Based on function radar can be divided into two types:

PRIMARY OR SIMPLE RADAR

SECONDARY RADAR

Primary radar or the simple radar locates a target by procedure described in section.

But in cases as controlling of air traffic, the controller must be able to identify the

aircraft and find whether it is a friend or foe. It is also desired to know the height of

aircraft.

To give controller this information second radar called the “SECONDARY

SURVEILLANCE RADAR”, (SSR) is used. This works differently and need the help

of the target aircraft it séance out a sequence of pulses to an electronic BLACK BOX

called the TRANSPONDER, fitted on the aircraft. The transponder is connected to

the aircrafts altimeter (the device which measures the planes altitude) to transmit back

the coded message to the radar about its status and altitude. Military aircrafts uses a

similar kind of radar system with secrete code to make sure that it is friend or foe, a

hostile aircraft does not know what code to transmit back to the ground station for the

corresponding receiver code.

IFF UNIT

IFF is basically a radar bacon system employed for the purpose of general

identification of military targets .The bacon system when used for the control of civil

air traffic is called as SECONDARY SURVEILLANCE RADAR (SSR).

Primary radar locates an object by transmitting signal and detecting the reflected echo. A secondary radar system is basically very similar to primary radar system except that the returned signal is radiated from the transmitter on

37

board the target rather then by reflection, i.e. it operates with a cooperative ‘active’ target while the primary radar operates with “passive target’.

Secondary radar system consists of an interrogative and a transponder. The

interrogator transmitter in the ground station interrogates transponder equipped

aircraft, providing two way data communication on different transmitter and receiver

frequency. The transponder on board the aircraft on receipt of a chain of pulses from

ground interrogator, automatically transmit the reply, coded for the purpose of

identification, is received back to the ground interrogator where it is decoded and

displayed on a radar type presentation.

ADVANTAGES OF SSR OVER PRIMARY RADAR

Separate transmitting and receiving frequencies eliminate ground and whiter

return problems.

Reply pulses are stronger then echo signal of primary radar.

Reply signal is independent of the target cross section.

Interrogation and reply path coding provide discrete target identification and

altitude.

The interrogate and reply mode works on the L band at 1030 MHz and the airborne

transponder works at 1090 MHz.

The SSR operates on the same frequency channel for both military and civil air traffic

control by using compatible airborne aircraft

38

Basic Radar System

A basic radar system is spilt up into a transmitter, switch, antenna, receiver,

data recorder, processor and some sort of output display.  Everything starts with the

transmitter as it transmits a high power pulse to a switch, which then directs the pulse

to be transmitted out an antenna.  Just after the antenna is finished transmitting the

pulse, the switch switches control to the receiver, which allows the antenna to receive

echoed signals.  Once the signals are received the switch then transfers control back

to the transmitter to transmit another signal.  The switch may toggle control between

the transmitter and the receiver as much as 1000 times per second.

Any received signals from the receiver are then sent to a data recorder for

storage on a disk or tape.  Later the data must be processed to be interpreted into

something useful, which would go on a Pulse Width and Bandwidth:

Some radar transmitters do not transmit constant, uninterrupted electromagnetic

waves.  Instead, they transmit rhythmic pulses of EM waves with a set amount of

time in between each pulse.  The pulse itself would consist of an EM wave of several

wavelengths with some dead time after it in which there are no transmissions.  The

time between each pulse is called the pulse repetition time (PRT) and the number of

pulses transmitted in one second is called the pulse repetition frequency (PRF).   The

39

time taken for each pulse to be transmitted is called the pulse width (PW) or pulse

duration.  Typically they can be around 0.1 microseconds long for penetrating radars

or 10-50 microseconds long for imaging radars (a display. microsecond is a millionth

of a second).

Mathematically,

PRT = 1 / PRF

or

PRF = 1 / PRT

WORKING OF A SIMPLE RADAR

A radar system, as found on many merchants’ ships, has three main parts:

The antenna unit or the scanner

The transmitter receiver or ‘transceiver’ and

The visual display unit

The antenna is two or three meter wide and focuses pulses off very high

frequency radio energy into a narrow vertical beam. The frequency of the radio

waves is basically about 10,000 MHz. The antenna is rotated at the rate of 10 to

25 rpm so that radar beam swaps through 300degree Celsius all around the ship

out to a range of about 90 kms.

In all radar it is vital that the transmitting and the receiving in a transceiver

are in close harmony. Every thing depends on accurate measurement of the time

that passes between the transmission of pulse and the return of the echo. About

1000, pulses per second are transmitted. Though it is varied to suit the

requirements. Short pulses are best for short-range work, longer pulses are best

for longer-range work.

40

An important part of transceiver circuit is ‘modular circuit’. This ‘keys’ the

transmitter so that it oscillates, or pulses for the right length of time. The pulses so

designed are ‘video pulses’. These pulses are short range pulses hence can’t serve out

the purpose of long range work .In order to modify these pulses to long range pulses

or the RF pulses, we need to generate the power. The transmitted power is generated

in a device called the “magnetron” which can handle all these short pulses and very

high oscillations.

Between these pulses, the transmitter is switched off and isolated. The weak

echoes from the target are picked up by the antenna and fed into the receiver. To

avoid overlapping of these echoes with the next transmitted pulse, another device

called ‘duplexer’ is used. Thus by means of the duplexer, undisturbed two-way

communication is established. The RF echoes emerging from the duplexer are now

fed to the mixer where they are mixed with the RF energy. These pulses are generated

by the means of a local oscillator. Once two are mixed, a signal is produced in the

output which is of intermediate frequency range or IF range .The IF signal is received

by the receiver by the receiver where it is demodulated to video frequency signal

range, amplified, and then passed to the display system.

The display system usually carried out the control necessary for the operation

of whole radar .It has a cathode ray gun, which consists of a electron gun in its neck.

The gun shouts electron to the phosphorescent screen at the far end. Phosphorescent

screen glows when hit by an electron and the resulting spot can be seen through the

glass face.

The screen is circular in shape and I calibrated in the edges .The electron beam travels

from the center of the edge. This radio motion of the electron is known as trace is

matched with the rotation of the antenna. So when the calibration is at zero degree on

the tube calibration, the antenna is pointing to the dead ahead. The beginning of each

trace corresponds exactly which the moment at which the suppression radar energy is

transmitted.

41

The basic idea behind radar is very simple: a signal is transmitted, it bounces off

an object and some type of receiver later receives it.  They use certain kinds of

electromagnetic waves called radio waves and microwaves.  This is where the name

RADAR comes from (Radio Detection And Ranging).  Sound is used as a signal to

detect objects in devices called SONAR (Sound Navigation Ranging).  Another type

of signal used that is relatively new is laser light that is used in devices called LIDAR

(Light Detection And Ranging). 

           Once the radar receives the returned signal, it calculates useful information

from it such as the time taken for it to be received, the strength of the returned signal,

or the change in frequency of the signal. 

RADAR EQUATION

The amount of power Pr returning to the receiving antenna is given by the radar

equation:

where

Pt = transmitter power

Gt = gain of the transmitting antenna

Ar = effective aperture (area) of the receiving antenna

σ = radar cross section, or scattering coefficient, of the target

F = pattern propagation factor

Rt = distance from the transmitter to the target

Rr = distance from the target to the receiver.

In the common case where the transmitter and the receiver are at the same location, Rt

= Rr and the term Rt2 Rr

2 can be replaced by R4, where R is the range. This yields:

42

This shows that the received power declines as the fourth power of the range,

which means that the reflected power from distant targets is very, very small.

The equation above with F = 1 is a simplification for vacuum without

interference. The propagation factor accounts for the effects of multipath and

shadowing and depends on the details of the environment. In a real-world situation,

pathloss effects should also be considered.

APPLICATIONS OF RADAR

Radar has been employed on the ground, in the air, on the sea and in space.

Ground – based radar has been applied chiefly to the detection, location, and tracking

of the aircraft or space target. Shipboard radar is used as a navigation aid and safety

device to locate buoys, shorelines and other ships as well as for observing aircraft.

Airborne radar may be used to detect other aircraft, ships, or land vehicles or it may

be used for mapping of land, storm avoidance, terrain avoidance and navigation. In

space, radar has assist in the guidance of spacecraft and for remote sensing of the land

and sea.

The major use of radar, and contributor of the cost of almost all of its

development, has been the military; although there has been increasingly important

civil application, chiefly for marine and air navigation. The major areas of radar

application are briefly described below:

Air Traffic Control (ATC): Radar is employed throughout the world

for the purpose of safely controlling air traffic route and in the vicinity of

Airport. Aircraft and ground vehicular traffic at large airport are monitored by

means of high - resolution radar. Radar has been used with GCA (ground

control approach) system to guide aircraft to a safe landing in bad weather.

43

Ship Safety: Radar is used for enhancing the safety of ship travel by

warning of ship potential collision with other ships, and for detecting

navigation buoys, especially in poor visibility. Automatic detection and

tracking equipment are commercially available for use with radar for the

purpose of collision avoidance. Shore – based radar of moderately high

resolution is also used for the surveillance of harbors as an aid to navigation.

Space: Space vehicles have used radar for rendezvous and docking and for

landing on the moon. Some of the largest ground based radar is for the

detection and tracking of satellite.

Remote Sensing: All radar is a remote sensor. Radar has been used as a

remote sensor of the weather. It is also used to probe the moon and planets.

The ionospheric sounder, an important adjunct for HF (short wave)

communications, is radar. Remote sensing with radar is also concerned with

earth resources, which include the measurement and mapping of sea

condition, water resources, ice cover, agriculture, forestry condition,

geological information and environmental pollution.

Law Enforcement: In addition to the wide use of radar to measure the

speed of automobile traffic by highway police, radar has also been employed

as a means for the detection of intruders.

Military: Many of the civilian application of the radar are also employed

by the military. The traditional role of radar for military application has been

for surveillance, navigation and for the control and guidance of weapon.

44

SURVEILLANCE RADAR EQUIPMENT (SRE)

RADAR ELECTRONIC CABINET (REC)

The REC cabinet contains at the right side in suitable comportment the first board with all strips of the RF exciter assembly, a second board, contains instead the IF assembly strips; and the IF SLB Assembly. A control panel is mounted on top of the cabinet containing breakers commands and controls. A multi-voltage power supply is situated in the cabinet. A view of the REC is given in figure 4.2.3; it contains the following subassemblies: - Power Control Panel; - Power Supplies; - RF Exciter Assembly; - IF Assembly; - Blowers and Fans Control Bite modules, - Digital Receiver Unit, - Two RSP assemblies, - Two RDP assemblies.

Power SuppliesThe REC power supply section receives 220V/380V a.c. 50 Hz three phase main supply and produces all the a.c. and d.c. voltages necessary to the REC unit, FER units and the REC cooling blowers. D.c. voltages are produced by switching regulators and are protected against transients and surge currents. Overload, overvoltages and overtemperature protections are also implemented; in case of overtemperature the Power Supply section interrupts the output voltages.

45

RF Exciter The aim of the RF exciter is to generate the RF signal to drive the Transmitter and the TTG. With this objective, it accepts one of the signals generated by either Stalo Synthesizer (10 frequencies each) that is, therefore, amplified by the STALO MEDIUM POWER AMPLIFIER and finally it is divided, in power, by four with one hybrid Power Divider. Three of the outputs of the Power Divider are sent to the FER units, the fourth to the STALO Mixer inside the RF Driver Amplifier and the others are terminated with a 50 OHM load. . The Medium Power RF amplifiers and the High Power RF amplifiers amplify the signal and send it to the TRANSMITTER. An output with coupler is sent to the DIGITAL ATTENUATOR from the MEDIUM POWER RF AMPLIFIER to generate the TTG signal (Test Target).

IF Receiver Assembly The IF Assembly contains many strips that carries out various tasks. All circuits dedicated to frequency generation are inside this assembly, the PRE-IF amplification, phase detection, the signal processors selection and the interface with the BITE circuits. The redundant frequency generation section is comprised of: -two Stalo Synthesizers; -one COHO; -one DIGITAL Expander; -one Generator; -one Distributor. The Stalo Synthesizers (ODD and EVEN) produce 20 frequencies that are used by the Stalo MPA (A and B) and constitutes the STALO signal distributed to the Hybrid and to two Power Dividers contained in the Exciter Assembly.

SLB FunctionThe SLB function is comprised of four strips. The S-BAND omni antenna furnishes the radar with a reception beam dedicated to the

46

SLB channel that is then sent , by means of the SLB/FER Assembly, to the IF SLB channel. The IF SLB channel is the same as the Air Target-IF Receiver (MAIN and AUX).

FRONT END RECEIVERSThe three front End Receivers are located externally to the REC cabinet and accept in input the RF signals coming from the antenna and generate three PRE-IF signals; the first and the second (main and auxiliary) are used for target detection (split into air and surface) and the third for the IF SLB Receiver. The units that make up the group are: - One Waveguide Switch; - Three Front End Receivers (FER);

Waveguide SwitchThis switch is used to route the signal received through the MAIN Antenna Beam towards the Aux Front End Receiver in case of a malfunction along the Main line. In the normal position, the MAIN beam is sent to the Main FER while the beam coming from the auxiliary antenna is sent to the AUX FER.

Front End ReceiverThe Front End Receiver carries out the following tasks: - it protects the receiver during the transmission of high power leakage signals; - it attenuates the signals received (STC); - it filters the signals in input that are outside of the useful band; - it amplifies the signal received with a L.N.A.; - it converts (down) the signals received to IF signals (mixer); - it checks malfunctions of the TR tube by means of the BITE. Every Front End Receiver contains the following assemblies: - Receiver Protector Spec. - Band Pass Filters - Low Noise Amplifier - RF Isolator - Mixer - Low Pass Filter - Band-Pass Filter

47

Radar Signal Processor– General Description The Radar Signal Processor (RSP) conducts some basic functions of the radar such as target detection, disturbance filtering AGC of receivers, STC control. It is comprised of three

ATCR-33S INDIA Receiver Unit Functional Technical Description - Air Target Signal Processor (ATSP), dedicated to the detection of aircraft; - Surface Target Signal Processor (STSP), dedicated to the detection of targets on the sea surface; - Side Lobe Blanking Signal Processor (SLBSP), dedicated to the blanking of detections generated by signals entering the sidelobes of the antenna, and the detection of jamming on the main lobe (Jammer Strobe). The three signal processing sections above listed provide to the Radar Data Processor (RDP) the plots of the detected Air Targets, the detected Surface Targets and the jamming messages that can affect the post processing of both the air and the surface targets. The plots are supplied together with information about the detection conditions (strength and number of thresholds passing). The ATSP and the SLBSP perform a coherent signal processing, working on I & Q signals coming from the phase detectors of the corresponding receiver channels. The STSP processes incoherently the input signal, which has been envelope detected with a logarithmic characteristics in the Surface Target Reception Channel.

Operative Modes

There are two main modes of operation of the signal processors:

- Coherent Processing (mode 1);

- Incoherent Processing (mode 2).

The mode 1 is the normal mode, and it is related to the use of constant radio

frequency

48

during a coherent processing interval (CPI) cycle (6 pulses). When this is the active

mode, all

the signal processors work normally, i.e. ATSP performs the AMTD function, the

SLBSP is

inserted, and the STSP is active.

The mode 2 corresponds to the use of variable radio frequency, changing from pulse

to

pulse (frequency agility). This condition inhibits the possibility to coherently process

the radar

signals and then:

- The STSP works normally.

- The ATSP works with non coherent integration

- The SLBSP is excluded.

In other words, when in mode 2, the radar has not the capability of:

- Conveniently filter the clutter;

- Improve the SNR by the coherent integration;

- Estimate the target radial velocity and suffers blind speeds.

- Contrasting the jamming through the sidelobes

Signal Processors Display

The Signal Processors provide several signals that can be displayed on the

Maintenance Monitor; these signals are divided into two categories:

- VIDEO signals;

- MAP signals.

1) VIDEO Signals

Air and surface target videos can be individually displayed or combined.

Two types of video signals can be displayed for the resulting combinations, namely:

Normal Video and Composite Video.

- Normal Video (multi level, 7 bit) is obtained from the output of the FIR (Finite

49

Impulse Response) filters of the ATSP and preset thresholds and shall be used

to indicate the location and intensity of clutter such as storm, mountains,

coastlines and towers; the signal sent to the display is obtained taking the output

of the filter providing the maximum amplitude, for each range bin, among the

selected filter. Using the Local Control Panel it is possible to limit the selection

among a reduced subset of filters, up to a single filter.

- Composite Video is the operational binary video that indicates all the detections

(targets and/or false alarms), eventually filter by filter.

2) MAPS Signals

Different types of maps or functional signals, can be displayed (filled area or contours

only):

- Jam Strobe Map (JS)

- Strong Target Adaptive Cancellation (STAC CPI)

- Fine Doppler Maps (one selected among N-2) (12 bit) (FDM)

- Weight Selection Map (2 bit) (WSM)

- False Alarm Normalizer Map (one selected among N) (FANM)

-Clutter Sensor Map (4 bit) (CLSM)

The following maps (stored in EEPROM) can be displayed:

- Censoring Level Map (CLM)

- Autogate Overriding Map (2 bit) Criteria (ACOM)

- Detection Overriding Map (3 bit) Criteria (DCOM)

- Detection Blanking Map (2 bit) (DBM)

- Second Time Echoes Map (STEM)

(1 bit= logic AND function in a CPI pair, or not)

- Main BSTC assigned attenuation (STC1)

(indicates the regions where the STC attenuation

is greater than an assigned value, for the main beam) (8bit)

- Jammer Sector (1 bit = enable Jam Strobe) (JAMM).

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AIR Target Signal Processor (ATSP) Characteristics

The ATSP main functions are

- I & Q analog to digital conversion (12 bits)

- Long Pulse/short pulse alignment

- I & Q correction

- MTD filtering

- Magnitude of filter outputs

- Thresholds control system with:

- Doppler filters outputs scan by scan averaging thresholds (FDM);

- fixed thresholds;

- adaptive CFAR thresholds (autogate);

- censoring thresholds.

- STC

- Interference and Sun strobe detection

- Automatic Gain Control (AGC)

- Strong Target Adaptive Control (STAC)

- Incoherent processing, for pulse to pulse agility

- Signals for performance display

- Second time-around echo suppression.

The above functions are supported by a number of parameters that are programmable

and adjustable by means of the Local Control Panel.

The ATSP processes the received signal and sends out the Target Primitive Reports

with the following contents:

- magnitude (10 bits)

- status flags (3 bits).

The above data are transferred to the RDP.

The ATSP generates its internal timing starting from fundamental synchronisms

received from the RDP (System Timing function).

These synchronisms are:

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- North Reference Pulse

- CPI trigger

AMTD Filtering

The objective of the AMTD is essentially that of detecting targets that are selected on

the basis of their doppler frequency.

It conducts coherent integration and filtering of clutter with a bank of N FIR digital

filters tuned on a portion of the doppler spectrum.

Selectivity in doppler is realized, in fact, by these transverse filters in time sharing,

allowing incoherent integration in groups of “n” or “m” sweeps

Adaptive and Environmental Functions

Some adaptive functions are contained within the ATSP to filter all unwanted signals

and to maintain dynamic range and CFAR of the processing system.

These functions include the real time sensors relative to the environment and they

memorize in a map (one for each function) the appropriate value to be applied (for

example,

threshold level, STC value, etc.).

These maps are also updated continuously. The circuits being examined are

represented in the general block diagram of the Signal Processor in figure 4.2.9.

The functions mentioned above are divided into two groups:

1) Functions that support detection criteria such as:

- estimation of the threshold, scan by scan, for the N filters with N-1 (6 at most)

Fine Doppler Map (FDM);

- Definition of vehicular traffic areas and fixed strong echoes with the Censoring

Level Map (CLM, contained in circuit FA);

- Angel activity detection in output from each doppler filter. For the filters where

angels are detected, the selected detection threshold is increased by a

preselectable quantity. This function is carried out with N False Alarm

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Normalizer Maps (FAN, contained in the MO circuit);

- Adaptive threshold characteristics and spatial selection (CA-CFAR) with the

Autogate Criterium Overriding Map (ACOM, contained in the FA circuit);

- Detection criterium selection with the relative map (DCOM : Detection

Criterium Overriding Map, contained in the FA circuit);

- Automatic definition of rainy areas with the clutter map (CLSMAP);

- Blanking of the Primitive Reports of a filter or of a group of filters in particular

areas with the Detection Blanking Map (DBM, contained in the FA circuit).

2) Environmental and adaptive functions that have the aim of increasing the signal

with

respect to clutter, permitting a high probability of detection over the entire volume

covered;

These functions are:

- FIR filters weight selection with the Weight Selection Map;

- STC control function that updates the attenuation of the signals received.

SLB Reception Channel

The Side Lobe Blanking (SLB) Reception Channel functional area receives the echo signal from the Antenna Group in the "S-Band", down converts it into an appropriate IF for processing, performs pulse compression and phase decoding This functional area is made up by the same type of modules used for the Main Reception Channel, however few functional differences exist. This functional area is composed of the following parts: a) SLB FER (Front End Receiver) including: - Receiver Protector - Band Pass Filter - Low Noise Amplifier - RF Isolator - Mixer - Stalo Band Pass Filter

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-Low Pass Filter b) IF Preamplifier and Mixer Module c) SAW Compressor Module d) Phase Detector Module

Signal Processor BITE

The BITE system that controls the Signal Processors can be divided into the two following criteria: BITE ON LINE: 1) BITE-ON-LINE of the processing cards conducted by the "BITE 1" card (BA); 2) BITE-ON-LINE of the Timing cards conducted by the "BITE TIMING" card (BE); 3) BITE-ON-LINE of the cards containing maps. BITE OFF LINE The BITE ON LINE is active during operation of the apparatus. The BITE OFF LINE is activated once the apparatus has been turned off.

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CONCLUSIONThe industrial training at Bharat Electronics Limited, Ghaziabad has

given us an exposure to the activities at a large public sector-undertaking

unit. This being a large organization deals with wide spectrum of

technologies. The exposure on RECEIVER OF SRE RADAR has given

us great confidence and knowledge.

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