ACKNOWLEDGEMENT

I take this opportunity to express my sincere gratitude towards Training and placement officer of my college for forwarding my training letter to Bharat Electronics, Ghaziabad and also to Ms. Abha Mathur (Mgr.) HRD, Bharat Electronics, Ghaziabad for accepting my letter and allowing me to complete my training in Bharat Electronics Limited.

I am extremely grateful to Mr. Jagdish Chand, (AGM, RADAR SBU), Mr. Dhyan Singh, (Sr.DGM, RADAR SBU), Bharat Electronics, for permitting me to join CAR- RADAR SBU.Further I would like to thank Ms. Laxmi Chauhan, Mr. Ankur kumar for their time to time guidance and help extended during each stage our project.

I am grateful to Mr. R.N. Tyagi, HRD to guide and help me throughout my project. It is not without his help I could have been able to complete my training here. I would like to express my deep satisfaction and gratitude for their support for their kind help extended during the entire period of training.

Finally, I would like to thanks each and every member of BEL family for making me feel comfortable and helping me in every possible manner.

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PREFACE

The six week industrial training is a part of our B.Tech, Electronics and Communication Engineering curriculum. Practical Industrial Training mainly aims at making one aware of industrial environment; which means that one gets to know the limitation, constraint and freedom under which an engineer works. One also gets an opportunity to watch from close quarter that indicates manager relation. This training mainly involves complete knowledge about designing, assembling and manufacturing process of various equipments manufactured by an industry.

During this six weeks period, as a student, I had a great opportunity of understanding the various industrial practices at BEL Ghazoabad. Most of the theoretical knowledge that has been gained during our course is useful only if it can be applied to production and services in the industry.

My sphere of knowledge was expanded both at technical and personal level. I not only got chance to work on Live Project but also witnessed the related industrial processes and got acquainted to many of the prevalent technologies.

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INTRODUCTION: BHARAT ELECTRONICS LIMITED

INDUSTRY

Bharat Electronics Limited (BEL) was established in 1954 as a Public Sector Enterprise under the administrative control of Ministry of Defense as the fountain head to manufacture and supply electronics components and equipment. BEL, with a noteworthy history of pioneering achievements, has met the requirement of state-of-art professional electronic equipment for Defense, broadcasting, civil Defense 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 valve 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 equipment technology, its manufacturing and product assurance facilities have also undergone sea change. The design groups have CADDs facility, the manufacturing has CNC machines and a Mass Manufacture Facility, and Quality Control (QC) checks are performed 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 is spread over the entire Electro-magnetic (EM) spectrum 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 product ranges like Defense Communication, Radar's, Optical & Optoelectronics, Telecommunications, 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 Radar Systems Consultancy, Contract 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

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computers based application, both hardware and software. Most of its software requirements are in real time. EMCCA, software intensive naval 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 46 th 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 Electronic Companies by the Electronic Business Asia and within the top 100 worldwide Defense Companies by the Defense News, USA.

BEL has production units established at different parts of the country. The year of establishment and location are as follows:

S.NO YEAR OF ESTABLISHMENT

LOCATION

1. 1954 BANGALORE

2. 1972 GHAZIABAD

3. 1979 PUNE

4. 1979 TALOJA

5. 1984 HYDERABAD

6. 1984 PACHKULA

7. 1985 CHENNAI

8. 1985 MACHILLIPATNAM

9. 1986 KOTDWARA

Table 1: 9 units of BEL all over India

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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 Defense 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 Defense and other chosen fields of electronics through in-house Research and development as well as through Collaboration/Co-operation with Defense/National Research Laboratories, International Companies, Universities and Academic Institutions.

• 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?

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BEL GHAZIABAD (UTTAR PRADESH)

The second largest Unit at Ghaziabad was set up in 1974 to manufacture special types of radar for the Air Defense Ground Environment Systems (Plan ADGES). The Unit provides Communication Systems to the Defense Forces and Microwave Communication Links to the various departments of the State and Central Govt. and other users. The Unit's product range included Static and Mobile Radar, Tropo scatter equipment, professional grade Antennae and Microwave components.

ORGANIZATION

The operations at BEL Ghaziabad are headed by General Manager with Additional/ Deputy General Manager heading various divisions as follows:

Design & Engineering Divisions

Development and Engineering-R

Development and Engineering-C

Development and Engineering-Antenna

1. Equipment Manufacturing Divisions :

Radar

Communication

Antenna

Systems

Microwave Components.

2. Support Divisions:

Material Management

Marketing & Customer Co-ordination

Quality Assurance & Torque

Central Services

PCB & Magnetics

Information Systems

Finance & Accounts

Personnel & Administration

Management Services.

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DESIGN & ENGINEERING

The pace of development and technological obsolescence in their field of electronics necessitates a strong Research and Development base. This is all the more important in the area of Defense Electronics. BEL Ghaziabad has since its inception laid a heavy emphasis on indigenous research and development. About 70% of its manufacture today relate to items developed in-house. For the development and production of the Mobile Tropo scatter System and the IFF 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 micro-computers and dedicated design application. About 170 graduate and post-graduate engineers are working on research and development and indication of the importance R&D has in BEL's growth.

Three Design and Engineering groups 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 CADDs 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 Defense services and professional user, 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 into various departments like Production Control, Works Assembly, and QC WORKS. The manufacture and control of production is through a central system, BELMAC, BEL's own homegrown ERP system.

Apart from conventional machines, BEL Ghaziabad has been equipped with several Computer Numerical Control (CNC) machines for ensuring 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 is 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.

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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, Inwards good store, Custom clearance Cell, Inventory management & disposal.

MARKETING AND CUSTOMER CO-ORDINATION

This division is responsible for 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 Defense 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.

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 only 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.

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Magnetic department makes all types 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 system called BELMAC.

FINANCE & ACCOUNTS:

The F&A division is divided into Budget & Compilation, Cost and Material Accounts, Bills Payable, Bill Receivable, Payrolls, Provident Fund, Cash Sections

PERSONNEL & ADMINISTRATION:

There are at present about 2300 employees at BEL Ghaziabad, of which more than 400 are graduate and post graduate engineers.

P&A Division is divided into various departments like Recruitment, Establishment, HRD, Welfare, Industrial Relations, Security and MI Room.

MANAGEMENT SERVICES:

This department deals with the flow of information to or from the company. It is broadly classified into three major sub-sections - Management Information System, Industrial engineering department and Safety.

PRODUCTION CONTROLThe main goals of the production control are:

To improve the profits of the company by better resource management

To ensure on-time delivery products

To improve the quality of product

To reduce the capital investment

To reduce working capital needs by better inventory management

Production control is responsible for producing the products, right from the stage engineering.

Drawings are received to the stage where it is store credited as finished product. Its basic function is to identify the parts/operations to be made, the best way of making them, the time when they have to be made and to arrange the production resources to the optimum.

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The commercial department obtains orders for equipments through quotations. The equipment stock order (ESO) is released by commercial department. Then the management services department issues work order for the quantity of equipment to be made. This is for the calculation for the cost of the project then D&E department develops the equipment and releases the following engineering documents:

KS : Key Sheet

PL : Part List

GA : General Assembly Diagram

CL : Connection List

WL : Wiring Diagram

Now the production control takes the responsibility of manufacturing the equipment. PC decides for items to be purchased from outside, for items to be manufactured by other companies and prepares documents for items to be made inside the company.

Documents issued by the PC:

I. Process sheet (fabrication): This process sheet indicates the process and the sequence of operation to be followed in various work cells and work centers. Every item is timed by productivity services.

II. Process sheet (Assembly): This is similar to PS (fabrication) except that it is used in electronics assembly, PCB assemblies, cable form and cable assemblies.

III.Process sheet (coils): This indicates operation analysis for transformer and coils.

IV. Schedule for RM, fasteners and PPs: This gives the gross requirements for raw materials, purchased parts, fasteners etc. Based on this material control department initiates procurement action and store requisitions are released with reference to this schedule.

TOOL PLANNING

1. Some of the items while under fabrication require the use of some jigs and fixtures.

2. The cost estimation, revenue and budget plans are got approved by the board of management

3. Standard hour is approved by the department. This is the time, which is decided to complete the job by a worker in a stipulated time, which is decided on the previous records of the shop, type of machine used and the nature of work.

4. Report on production value is evaluated for each unit.

The collaboration of all these subsystems and divisions leads to a coherent and precise functioning of the industry as a whole. The excellence and diligence of each and every person associative with BEL Ghaziabad, is rewarded with a plethora of customers from all fields of the world such as defense, communications, paramilitary, medicine, etc.

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CUSTOMER PROFILE & BEL PRODUCT RANGE

CUSTOMER RANGE OF PRODUCTSArmy Tactical and Strategic Communication Equipment and Systems, Secrecy Equipment,

Digital Switches, Battlefield Surveillance Radar, Air Defense and Fire Control Radar, Optoelectronic 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.

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.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 ofTelecommunications

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

Videsh SancharNigam and otherCorporate 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.

Table 2: Customers and products supplied

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ABOUT VARIOUS DEPARTMENTS

MICROWAVE INTEGRATED CIRCUITS

Frequencies greater than 1 GHz are termed as Microwaves. Microwave Integrated Circuit used extensively in production of subsystems for Radar and Communication equipment constitutes a very important part of technology for these systems are 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 facility of hybrid microwave components available at BEL Ghaziabad includes facility for preparation of substrates, assembly of miniaturized components on substrates, bonding and testing. Testing of these microwave components viz. Directional couplers, Waveguides, low noise amplifiers, phase shifters, synthesis etc. involve scalar as well as vector measurements. For this state of the network, analyses are used. Various losses such as return loss, bending loss, insertion loss are measured and testing is done in a way to minimize these losses.

MICROWAVE LAB

This section undertakes:

1. Manufacturing of films and microwave components to meet internal requirements.

2. Testing of low power antenna for which test-site is about 100 Km from the factory at Sohna.

The main component testing in this department is:

Oscillators

Amplifiers

Mixers

Radiation elements (e.g. Feeders)

Microwave components (e.g. Isolators, circulators, waveguides etc.)

Filters (e.g. LPF, BPF, Uniplexers, and Multiplexers etc.)

Functioning of component is listed below:

Frequency response

Noise figure

VSWR

Directivity and coupling

Power measurements

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Various instruments in the lab are:

Adaptor

Attenuator

Coupler

Mixer

Detector

ENVIRONMENTAL LAB

Various tests conducted in the environmental lab in BEL in order to ensure reliability. Reliability is defined as the probability of a device performing its purpose adequately for the period intended under the given operating conditions. In a given system reliability is given as

R = R1 * R2 * R3 ……

The standards available here are:

JSS 55555 - Joint Services Specifications (Military Standard of India)

Mil Standards - U.S. Military standards

QM333 - Civil Aviation and Police

TYPES OF TESTS

1. FIRST ARTICLE TEST (FAT)

These tests are performed on the prototype. If these tests are successful then the mass production is taken up. The tests are:

1. Vibration Test System2. High Temperature Operate and Storage3. Low Temperature Operate and Storage4. Damp Heat Operate and Storage5. Altitude Chamber6. Bump Test Machine7. Salt Fog Chamber8. Tropical Storage9. Mould Growth Chamber

2. ACCEPTANCE TEST PROCEDURE

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This sets on the extent to which a test is to be conducted and also decides what tests should be conducted. There are three types of tests:

a) Class A test: This test includes visual and dimensional checks. All equipments of regular production go through these checks. These include quality control and electrical tests.

b) Class B test: These are quality assurance and reliability tests. Only 10% of equipments go through these tests. They include quality control, electrical tests and some environmental tests.

c) Class C test: These are carried out on 1% of the components. All the environmental tests are performed. If any failure is seen, the component must be redesigned. Also the customer must be supplied with modified goods. This test comes in picture for bulk production only.

This is the area where the producer tries to cover in the warranty period. The repeated failures are detrimental to a company’s reputation as these are eliminated by screening while in manufacturing stage. The other screening is the stress screening method. This consists of:

a) HUMIDITY TEST: Humidity is created with the help of boilers and fans in the chamber. Required temperature and duration of the tests are selected as per the specified BEL standards.

b) ALTITUDE TEST: The conditions such as very low temperature (created with the help of cooling systems) and very low temperature and pressure (created with the help of a vacuum pump) are maintained in a chamber. These conditions are comparable to those at high altitudes where the products have to work.

c) AGEING AND THERMAL SHOCKS: One cycle of ageing is of 7 hours. Ageing is done to relieve the stresses developed in the PCB due to blazing, welding, riveting etc. The sample is first kept at ambient temperature (250 degree Celsius) and then cooled to -400 degree Celsius.

d) BUMP TEST: The sample is given bumps in one direction only, with the help of machine. The number of bumps to be given is set with the help of proper switches. The sample is operated after giving bumps. If it works properly, it is passed.

e) VIBRATION TEST:The sample is subjected to vibrations. Required frequency and amplitude for vibrations is selected accordingly.

f) SALT SPRAY TEST: Salt solution is sprayed in a chamber. The specimens are hanged in the chamber. The test helps to decide any corrosion that takes place due to spraying of solution.

g) RAIN TEST: In this test, conditions are created such that the sample is made to bath in heavy rain, so that if any problem arises in the sample due to rain that can be sorted accordingly.

h) DROP TEST : The sample is made to survive in such a environment where there is possibility of snow fall. Such conditions are created in a chamber, to sort out any problem arises due to this.

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i) ROADABILITY TEST: While doing bump test, bumps are given to the sample in unidirectional only. But in the roadability test, bumps are given to the sample in all the directions. It means that the test is being carried, considering the device to be moving in a zigzag manner on an uneven road. For e.g. in sand or in water etc. This test helps to make out any fault or loosening of components while moving the specimen from one place to another.

j) BOMB TEST: This is a test conducted for special types of samples. In this the samples are exposed to a situation like a bomb blast and it is checked whether the sample is able to bear the bomb explosion.

WALK IN CHAMBER

A very huge used for conducting humidity and temperature tests. The size of the chamber is such that a person can easily walk into it. It is for large sized specimens.

PCB FABRICATION

PCB is abbreviated form of printed circuit board. As the name suggests, in a PCB the electrical circuit is printed on a glass epoxy board. This reduces the complex writing network whose trouble shooting in case of shorting or misconnection is not easy.PCB fabrication is mostly done for house requirements. It also takes some external jobs.

Types of PCB’s

Single Sided: Having circuit pattern only on one side of the board. Double Sided: Having circuit pattern on both sides of the board. Multilayered: Having many layers of circuit.

BEL – Ghaziabad produces only single-sided and double-sided PCB’s.

FABRICATION OF SINGLE SIDED PCB’s:

1. A copper clad sheet is taken. It is cleaned and scrubbed. 2. The sheet is laminated with a photosensitive solution. 3. Positive photo paint of the required circuit is placed over the laminated sheet and it is subjected

to the UV light. As a result the transparent plate gets polymerized and the opaque part remains unpolymerized.

4. The plate is now dipped in solution in which the non-polymerized part gets dissolved. 5. Tin plating is done on the tracks obtained.6. Lamination of the plate is removed (stripping). 7. The unwanted copper from the plate is also removed by dipping it in the solution that dissolves

copper but not tin (etching). 8. Now drilling is done on the paths where the components are to be mounted. This process

fabricates PCB.

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PCB MANUFACTURING PROCESS:

1. Copper clad2. Drill location holes3. Drill holes for T.H.P. (Through Hole Plating)4. Clean scrub and laminate5. Photo print6. Develop7. Copper electroplate8. Tin electroplate9. Strip film10. Etch and clean11. Strip tin12. L.P.I.S.M. (Liquid Photo Imageable Solder Mask)13. Photo print14. Develop15. Thermal baking16. Hot air level17. Legend marking/Reverse marking18. Route and clean

But these PCB’s have the following disadvantages:

Due to very narrow spacing between adjacent tracks, there may be chance of short circuit if the soldering is done by hands between the components on opposite side.

Moisture or dust between the gaps may disrupt smooth soldering.

These disadvantages are overcome by soldered mask PCB’s. In the later one an additional film is put on the earlier fabricated PCB, leaving points where components are to be soldered.

TEST EQUIPMENT & AUTOMATION

TEST EQUIPMENT SUPPORT (TES) Main functions are:

Develops technical support to other departments. Repair of equipment in case of failure. Maintenance of equipments. Periodic calibration of equipments. Provide technical support to other departments. This includes:

1. Handling requests from the other department for equipments.2. Storage of rejected equipments.3. Approval of equipments to be purchased.

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This section deals with testing and the calibration of electronic equipments only the standards of this department are calibrated by National Physics Laboratory (NPL).

AUTOMATION TEST EQUIPMENT (ATE)

1. Component testing gives faults of various discrete components of a PCB.2. Integrated circuits tester tests various IC’s. 3. Functional testing compares output to decide whether the function is being performed to the

desired level of accuracy.

WORKS ASSEMBLY

This department plays an important role in the production. Its main function is to assemble various components, equipment’s and instruments in a particular procedure. It has two sections, namely:

1. PCB assembly2. Electronic assembly

In PCB assembly, the different types of PCB are assembled as per BEL standards. PCB is received from the PCB department on which soldering of component is done either by hand soldering or wave soldering.

HAND SOLDERING: In case of hand soldering, soldering is done manually.

WAVE SOLDERING: Wave soldering is a procedure in which PCB’s are fed to the wave soldering machine from the opening on one side and the soldering is done by machine and after the soldering is done PCB’s are collected from the another opening of the machine and after that cleaning is done.

The PCB’s are then sent to testing department for testing according to the product.

ASSEMBLY

In electronic assembly, the cable assemblies, cable forms modules, drawers, racks and shelters are assembled. Every shelter (e.g. - DMT) is made of racks, racks are made up of drawers, drawers are made up of modules and modules are made up of PCB’s, cable assembly and cable forms.

Every module or drawer before using in next assembly is sent for testing according to their PTP. Shop planning collects the purchase from the IG store, takes fabricated parts, PCB’s etc. from planning stores and issued to the assembly department as per the part list of the assembly to be made. The documents issued to the assembly are:

KS : Key SheetPL : Parts List

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CL : Connection List for cable formWL : Wiring List for modulesWD : Wiring DiagramGA : General Assembly diagram

This department has been broadly classified as:

1. WORK ASSEMBLY RADAR e.g. : INDRA-2 , REPORTER ,CAR2. 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 process 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 connection to be made and brief idea about all components.4) Writing list of all components.

Process Sheet (assembly)

All operations fill the work order and shop order in operator’s time card (OTC). They punch the time of starting the job and its finishing time. By this productivity services calculates the time taken to complete the job.

Efficiency = time allotted in shop order X 100

Actual time taken

Time allotted is so called standard hours.

This deals with the assembly of common projects e.g. DMT, 2 GHz radio relay, Mobile tropo, Static RRD etc.

MAGNETICS

This department manufactures all types of transformers and coils that are used in various equipments manufactured by BEL. This department basically consists of four sections:

1. Planning section2. Mechanical section3. Molding section4. Inspection section

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The D&E department gives the following descriptions to the magnetics department. They are as follows:

Number of layers Number of turns Type of winding Gap in core Insulation between layers Ac/dc impedance Dielectric strength Electrical parameters and Earthing

The various transformers being made are:

Open type transformer Oil cooling type transformer Molding type transformer PCB molding type transformer

The transformer is mechanically assembled, leads are taken out and checking of specification is done.

Winding machines are of three types:

Heavier ones- DNR for 0.1 to 0.4 mm diameter LC controlled machines Toroidal machines having 32 operations from winding to mechanical assembly.

The various types of windings used are:

Hand winding Toroidal winding Sector winding Pitch winding Variable pitch winding Wave winding

Two main types of core used are:

E-type for 3-phase C-type for single phase

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Following procedure involved in the manufacture of the transformer is as follows:

1. Formers of glass epoxy2. Winding3. Core winding4. Varnishing5. Impregnation – In this process various varnished coils are heated, then cooled, reheated

and put into vacuum. Then air is blown to remove the humidity.6. Molding – Araldite (a certain type of strong glue) mixed with black dye is used to

increase mechanical as well as electrical strength. Molding is done at 120 degree Celsius for 12 hours. A RDB compound is used for leakage protection. Oil is then boiled at 70 to 80 degree Celsius under vacuum condition to remove air bubbles trapped inside during manufacturing process. After this the coils are dipped in varnish and core is attached.

7. Painting8. Mechanical assembly9. Termination10. Stenciling11. Testing – Dielectric testing (both ac/dc) is done at 50 KV voltage.

During inspection, the following characteristics are checked:

a. Turns ratiob. DC resistance for each coilc. Inductanced. No load voltagee. Leakage

This section the material used for making transformer is Bakelite comprising male and female plates which are joined alternately to form a hollow rectangular box on which winding is done. Winding is done with different material and thickness of wire. The winding has specified number of layers with each layer having a specified number of turns. The distance between the two turns should be maintained constantly that is there should be no overlapping. The plastic layer is inserted between two consecutive layers.

Types of Windings:1) Layer Winding2) Wave Winding3) Bank Winding

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Different types of windings are done to control some parameters such as inductance and capacitance. Varying the spacing between the two turns can vary these parameters. Two consecutive turns act as capacitor. As gap between the turns increases the capacitance decreases and inductance increases. Since capacitance is inversely proportional to the gap between the plates of capacitor and inductance is directly proportional. After winding the core is inserted between the primary and secondary. Contact leads are taken out and molding is done for maximum heat dissipation. Rubber solution is used to give strength to the wires, so that they cannot break. This is done before molding. Varnishing is done as anti-fungus prevention for against environmental hazard. After compilation of manufacturing process it is sent for testing. Different parameters such as inductance, capacitance efficiency, turns ration, continuity are tested.

QUALITY CONTROL WORKS

According to some laid down standards, the quality control department ensures the quality of the product. The raw materials and components etc. purchased are inspected according to the specifications by the IG department. Similarly QC works department inspects all the items manufactured in the factory. The fabrication inspection checks all the fabricated parts and ensures that these are made as per the part drawing. Plating, Painting and stenciling etc are done and checked as per the BEL standards. The assembly inspection department inspects all the assembled parts such as PCB, cable assembly, cable form, modules, racks and shelters as per latest documents and BEL standards.

RADAR ASSEMBLY

This deals with the assembly of RADARS, e.g. INDRA-I, INDRA-II, FLY CATCHER, EMMCA, IRMA, REPORTER, CAR etc. In RADAR section RADAR being tested is REPORTER, FLY CATCHER, EMCCA, etc.

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RADAR (RADIO DETECTION AND RANGING)

RADAR AND ITS COMPOSITE ENVIRONMENT

INTRODUCTION

The two most basic functions of radar are inherent in the word, whose letters stand for Radio Detection and Ranging. Measurement of target angles has been included as a basic function of most radar, and Doppler velocity is often measured directly as a fourth basic quantity. Discrimination of the desired target from background noise and clutter is a prerequisite to detection and measurement, and resolution of surface features is essential to mapping or imaging radar. The block diagram of typical pulsed radar is shown in Figure. The equipment has been divided arbitrarily into seven subsystems, corresponding to the usual design specialties within the radar engineering field. The radar operation in more complex systems is controlled by a computer with specific actions initiated by a synchronizer, which in turn controls the time sequence of transmissions, receiver gates and gain settings, signal processing, and display. When called for by the synchronizer, the modulator applies a pulse of high voltage to the radio frequency (RF) amplifier, simultaneously with an RF drive signal from the exciter. The resulting high-power RF pulse is passed through transmission line or waveguide to the duplexer, which connects it to the antenna for radiation into space. The antenna shown is of the reflector type, steered mechanically by a servo-driven pedestal. A stationary array may also be used, with electrical steering of the radiated beam. After reflection from a target, the echo signal reenters the antenna, which is connected to the receiver preamplifier or mixer by the duplexer.

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Figure 1: Block diagram of RADAR

A local oscillator signal furnished by the exciter translates the echo frequency to one or more intermediate frequencies (IFs), which can be amplified, filtered, envelope or quadrature detected, and subjected to more refined signal processing. Data to control the antenna steering and to provide outputs to an associated computer are extracted from the time delay and modulation on the signal. There are many variations from the diagram of Figure that can be made in radars for specific applications, but the operating sequence described in the foregoing forms the basis of most common radar systems. This project provides the basics of radar and many of the relationships that are common to most forms of target-detection radar. The emphasis is on the goals established for the radar or the system that contains the radar.

CENTRAL ACQUISITION RADAR

INTRODUCTION

The designed Radar would be a stand-alone all-weather 3D surveillance radar. The radar operates in S-band and is capable of Track-While-Scan [TWS] of airborne targets up to 130 Kms, subject to line-of-sight clearance and radar horizon. The radar employs Multibeam coverage in the receive mode to provide for necessary discrimination in elevation data. It employs 8 beams to achieve elevation coverage of prescribed margin and a height ceiling of prescribed margin. The antenna is mechanically rotated in azimuth to provide 360 coverage. To get an optimum detection performance against various class of targets, different Antenna Rotation Rate [ARR] RPM modes are implemented and these can be selected by the operator.

The unique feature of the radar is, its operation is fully automated and controlled from a Radar Console with sufficient menus, keys and Hot keys. The designed Radar is an offshoot of the fully and successfully developed and demonstrated radar called as 3D Central Acquisition Radar (3D-CAR).

3D-CAR is designed to play the role of medium range surveillance radar mounted on a mobile platform. The radar carries out detection, tracking and interception of targets with an RCS of 2m2 upto 130 Kms in range. The antenna can be manually positioned at different look angles in steps. In the receive mode the eight beams cater for a height coverage of required margin. The IFF antenna is placed atop the main antenna and it integrates the IFF for including of IFF data with the Primary Radar Data.

The RDP (Radar Data Processor) is implemented on a SBC and is fully software-based system with adequate memory and external interfaces to handle upto 150 target tracks. Robust algorithms for filtering are used to lock on to maneuvering target upto 6g without loss of tracking.

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LAN interfaces are used to communicate with external systems. High-speed data transfer of target parameters can be done. This helps in data remoting upto a distance of 500 mtrs that can be extended with suitable repeaters. Facility for manual track indication for low speed targets and targets in heavy clutter zones are available to the console operator.

The color display has features for monitoring of radar performance, the radar output selection for radar modes of operation. Interfaces to radar control signals are built-in. The Radar generates different videos viz., Analog and Digital videos at the Receiver and Signal Processor. These are interfaced to the display over dedicated lines and displayed In addition to providing real time data on screen for viewing, the consoles will provide facility for training controllers/operators/ technical crew. The system is capable of creating targets and assigns values for range, azimuth, height and speed as defined by operator. It will enable the operator to control the motion of these targets for gaining/ loosing height, turning left/right, cruising, and rolling out. The software running on console will provide an online handy aid, for target interception. The training part of the software will be active as an offline facility or with tracked targets in real time. The offline mode will be capable of using recorded data.

Salient features of CAR:

1. 3D Surveillance Radar2. S-BAND 3. Capable of Track While Scan (TWS) of airborne Targets upto 150 Kms4. Coherent TWT based Transmitter5. Planar Array Antenna with low side lobes 6. Multiple beams in the receive mode. 7. ECCM (Side lobe blanking, Frequency Agility, Jammer analysis)8. Integrated IFF 9. System operation is controlled from Radar Console in Data centre.10. Redundant Power supply unit with UPS backup.

I have been working in Transmitter section of CAR developed by BEL, Ghaziabad. Before explaining the technical details of Transmitter of Radar, it is necessity to understand the general working of Radar.

Radar subsystems:

1. Multi-beam Antenna system2. Transmitter3. Receiver 4. Signal Processor 5. Radar Console6. Data centre7. Mobile Power Source8. IFF System

The Multi beam antenna system for Radar is planned to be realized to have 360 Coverage in Azimuth and prescribed coverage in elevation. The antenna will have a wide beam in transmit mode and eight simultaneous narrow beams in receive mode to give prescribed coverage in elevation.

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The requirement of Transmitter is to amplify the pulsed RF signal from few watts to high power RF signal while maintaining the phase noise (additive noise) to its minimal as demanded by the system.

The Low Power Microwave Subsystem includes the major portion of Receiver RF System of the 3D-Radar. The Multibeam Antenna receives the reflected signals from the target. These signals are amplified by the Low Noise Amplifier, down converted to IF Frequency using two-stage superheterodyne receiver.

The IF Output is given as final output of the Low Power Microwave Subsystem to be further processed in the signal processor.

Customization of the console for user application will be carried out in the software and hardware. The Display Console is the operator's center to initialize, remotely setup, operate, observe, and diagnose the radar, both online and offline. The Primary and secondary radar video, target tracks, plots, geographical map along with other diagnostic and configuration messages are presented in 2D.

The Signal Processor for Radar is realized as 8 parallel and identical channels. Each Signal Processor accepts IF videos from the corresponding RF Receiver channel (8 beams + 1 Omni) and provides detection reports to the Radar Data Extractor (RDE) independently for these 8 channels. The detection reports for each channel must have range and strength information in addition to the associated flags. Jammer data is also to be reported. Configuration and mode control, diagnostics and status reporting are done through a Radar Controller (RC).

The electronic equipment cabin is provided for installation of transmitter, signal processor, receiver, display console, IFF equipment and a working place for maintenance.

The Data centre is required to provide basic functions like viewing of the air picture, remote operation of Radar and radio communication. At the same time the cabin provides shelter for the operators, with reasonable level of comfort and, protected against heat, rain and dust.

Mobile power source is required to provide the main supply to Radar and Data Centre for electronic and mechanical units of Radar including air conditioning units.

The Identification Friend or Foe (IFF) system is a good example of a secondary radar system that is in wide use in the military environment. A great deal of valuable information can be provided to the secondary radar by the target’s transponder. The transponder provides an identifying code to the secondary radar that then uses the code and an associated data base system to look up aircraft origin and destination, flight number, aircraft type and even the numbers of personnel onboard. This type of information is clearly not available from a primary radar system.

Examples: ROHINI, REWATI, 3D TCR.

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3-phase,400V,50Hz

3-channel liq cooling in

3-channel liq cooling out

Air cooling in

SP signals

Air cooling out

Dry air

BIT0

BIT1

PRETRGGRID PULSE

RF outROHINITRANSMITTER

RF input

System status

RF PULSE

TRANSMITTER

INTRODUCTION

The transmitter for Radar is Coherent MOPA type that operates in S Band using TWT as the final amplifier. The transmitter is used to amplify the pulsed RF signal from low power RF signal to High power RF signal as demanded by the system. TWT dissipates large amount of energy, therefore it is subjected to both air and liquid cooling.

The input to the transmitter is 3 phase, 415V, 50 Hz, which is later amplified to the optimal value for driving the TWT amplifier.

Figure 2: Block diagram of ROHINI Transmitter

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The transmitter is designed to operate in the following modes defined as adequate controlled states .

TRANSMITTER MODES

a) OFF: All subsystems switched OFF

b) Cold Standby: Only LVPSU’s, TWT heater and Grid biases are switched ON. No High Voltage applied.

c) Hot Stand By: High Voltages applied, No RF and No grid Pulsing.

d) Transmission: RF power delivered to Antenna / matched load.

i) Full Power mode : Full RF Power delivered to the Antenna

ii) Reduced Power mode : The transmitter is operated at 1/10 of its full power based on the selection by the user.

iii) Fail safe mode : A low power at required duty delivered to antenna through vv Solid State Power Amplifier when liquid cooling fails.

TRANSMITTER CONTROL

a) Local : To control through control panel on the transmitter.

b) Remote control : To control from the operator console through control interface RS422.

MECHANICAL DESCRIPTION

Three rack configuration of Transmitter describes complete functionality of Transmitter

1. Control Rack Monitoring panel Control panel Synoptic panel CPC Inverter

2. High Voltage Rack FDM (Solid state Switching) Cathode Assembly Collector Assembly Blower Unit

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Heater Unit

3. Microwave Rack TWT RF Plumbing RF Drive Unit SSPA ION Pump Controller

Figure 3: Rack structure of Transmitter

GENERAL DESCRIPTION

The Transmitter amplifies the pulsed RF signal from few Watts to many KW while maintaining the phase noise (additive noise) to prescribed margin as demanded by the system. In addition, a Solid State Power Amplifier (SSPA) is provided, as a stand by option, to ensure fail-safe mode, in case of failure of liquid coolant.

It employs a Traveling Wave Tube as final power amplifier. Low power amplifier stage (RF Driver) amplifies pulsed RF signal from 1mW (0 dBm) to few W which is necessary to drive the TWT amplifier.

The RF Driver stage uses a PIN attenuator transistor followed by power amplifiers to amplify RF signal. This is followed by an isolator. The isolator protects the transistor power amplifiers against excessive

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reflections from TWT. The signal is thereafter passed through a DC, a RF switch and an attenuator to cater for the three transmission modes. The sampled output of the DC is used for monitoring the input RF signal to the TWT.

The RF Driver output is given to the input of TWT, which amplifies the pulsed RF signal from few Watts to a level of many kW at the TWT output. High power RF plumbing components are connected at the output of TWT.

The TWT output is given to an arc detector followed by a ferrite circulator. The Ferrite circulator is used to protect the microwave tube against failure /damage due to reflected power in case of excessive VSWR at Antenna input port. The output of

Ferrite Circulator is given to High Power Dual Directional Coupler (DDC), which is used for measuring the transmitted and reflected power. If reflected power exceeds the specified limit of VSWR, a video signal is generated to cut off the RF drive through control and protection circuit. The output of the DDC is given to Antenna. To connect all the components in the required form, flexible sections, E-bends, H-bends and straight sections are used.

Control and Protection Circuit ensures the sequential switching ON of the transmitter, continuous monitoring and interlocking of various parameters, detection and indication of errors. All these are achieved by dedicated hardware and software.Synoptic Panel consists of LEDs, switches and LCD display. LEDs are used to show the status of the transmitter. They also show the fault, if any, in the transmitter. The LCD display, mounted on Synoptic panel, is used to show the value of cathode voltage & current, collector voltage and current. It also displays the Filament voltage and current, Grid + ve and -ve voltages and RF forward power.

The Inverter unit converts the incoming ac supply to DC and then converts the DC to high frequency AC (Pulse width controlled square wave) operating at 20 kHz. The output of the Inverter unit is given to HV rack for generation of Cathode and Collector voltages of the TWT amplifier.

High Voltage Power Supply unit (HVPSU) is used to supply high voltage to collector and cathode of the TWT.

The Floating Deck Modulator (FDM) unit generates filament voltage with surge current protection and also generates grid +ve and grid -ve voltages. Switching of grid voltage as per pulse width and PRF requirements are also provided by FDM.

Cooling Unit is used to cool the various components of the transmitter. The TWT, High Power Ferrite Isolator, high Voltage Power supplies and RF dummy load are cooled with de-ionized water and ethylene glycol mixture.

Forced air-cooling is employed to cool other components using ambient air which is filtered to ensure dust free air. The Dry Air unit ensures that the wave guide is at all times pressurized and dry.

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RF DRIVER TWT

FIL, GRID, CATHODE, COLLECTOR SUPPLY

COUPLER

FWD AND RFLECTED PWR MONITORLIQUID COOLING

TOANTENNA

SSPA

W/GSWITCH

Figure 4: Block diagram of transmitter

DETAILED DESCRIPTION

CONTROL RACK

Figure 5: Control rack

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Control Rack provides the protection controls and indications. As mentioned before, this rack is divided in five sections according to their functions.

1. Monitoring Panel

The Monitoring Panel provides monitoring ports for measuring of trigger signals to the transmitter, liquid cooling status, collector and cathode Inverter currents and bridge voltages. It provides an emergency switch OFF button and digital displays for collector and cathode voltages.

2. Control Panel

The control panel controls the power supplies of various units such as the fans, heater, LVPSU, Inverter, Modulator, RF Drive Unit and SSPA. The hour meters for filament, EHT and RF are also placed on the control panel.

3. Synoptic Panel

Synoptic Panel is located above the Control and Protection Circuit (CPC). It indicates the faults and status signals generated by CPC. Green LEDs represent status signals while Red LEDs represent faults. Audio alarms are also provided to indicate faults.

4. Control and Protection Circuits

The CPC ensures the sequential switching ON/OFF of the transmitter, continuous monitoring and interlocking of various parameters, detection and indication of errors.

CPC card Configuration comprises of ten different cards.

COMPARATOR CARD-I COMPARATOR CARD-II COMPARATOR CARD-III TIMING CARD SSPA CTRL CARD F TO V CARD OPTPISOLATOR CARD MC-I CARD MC-II CARD OPTO TRANSCEIVER CARD

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TO RADARCONTROLLER

CO

MP

AR

AT

OR

C

AR

DS

EHT VOLSAMPLES

RF PARAMETERS

OPTICAL LINKS&

F/V CARD

GRID VOL SAMPLES

FILVOL & I

SAMPLES

OP

TO

ISO

LA

TO

R

CA

RD

SSPACTRL CARD

COOLING CONDITIONS

TIMING CARD

RADARTIMINGS

SWITCH ON COMMANDS

TO SOLIDSTATE RELAYSFOR HV, MAINS

ON

STATUS STATUS

FRONT PANELWITH SWITCHES, LED

& LCD DISPLAY

LCD INTERFACE

SWITCH ON COMMANDS

HV POWER SUPPLIES

EHT PROBESCROW BAR

TWT

LIQUIDCOOLING

UNIT

FLOATINGDECK

MODULATORAT - 45KV

POWERDISTRIBUTION

3Ø 50Hz400V AC IN

RF DRIVER&

DIR COUPLERS

EHT CURR SAMPLES

BEAM CURR, COLL CURRCATH CURR

INPUTPOWERSTATUS

CROW BAR SIGNAL

GRID

PULSE

MICRO-

CONTROLLER

CARD

Figure 6: Block diagram of CPC5. Inverter

The Inverter is the main functional block of the (cathode/collector) HV Power supplies. A number of indicators are placed on the front panel of the Inverter unit.

AC-DC CARD CATHODE PROTECTION CARD CATHODE IGBT DRIVER CARD COLLECTOR PROTECTION CARD COLLECTOR IGBT DRIVER CARD SOFT START CARD TEMPERATURE SENSOR CARD ZENER CARD (For Cathode and Collector) CURRENT SENSOR CARD (For Cathode and Collector) CURRENT SENSOR (PEAK) CARD (For Cathode and Coll.)

HIGH VOLTAGE RACK

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This is central block of the transmitter, where cabins for HV Cathode and Collector are assembled. Above this is a FDM block where all the cards are installed and insulated from the transmitter that works on HV.As mentioned earlier, High Voltage Rack is divided in five more units. Each unit has its defined working.

Figure 7: High voltage rack

1. FDM (Floating Deck Modulator)

In FDM there seven functional cards, which are as follows:

• LVPS Card• Grid Bias Card• Positive Grid Supply Card • Switch Card• Filament Supply & Timer Card-1• Filament Supply & Timer Card-2

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Isolation

transformer

230V- ph-ph50Hz

FDM

FIL

GRID

CATHODE

Fil VoltageFil CurrentGrid PositiveGrid negative

To CPCOptical links

To TWT

Grid PulseFrom CPCOptical link

• V to F Card

Figure 8: Block diagram of FDM

Figure 9: FDM

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MICROWAVE RACK

Figure 10: Block diagram of microwave rack

The microwave unit consists of the following functional assemblies:

Low power amplifier [RF drive unit] High power TWT amplifier RF Plumbing, Wave-guide switch & dummy load Solid state power amplifier (2 kW) for low power transmission mode TWT ion pump supply Resistive TWT anode divider Microwave power measurement circuits Air cooling components

Low Power Driver for TWT (RF Driver)

Low Power amplifier stage (RF Driver) amplifies pulsed RF signal from 1mW (0dBm) to few Watts power, necessary to drive the TWT amplifier. This low power RF Driver consists of following stages:

Page | 35

(a) Transistor Power amplifier : Amplifies the Pulsed signal from 0dBm to 37dBm

(b) Separating isolator : Used to protect the transistor power amplifier against excessive reflections from TWT.

(c) Directional Coupler : To monitor the power available at the input TWT.

Figure given below shows the Input and output diagram of RF Driver

Figure 11: Block diagram of RF driver

High Power Microwave Stage

High Power Microwave consists of mainly TWT, which amplifies the pulsed RF signal received from the RF Driver of few watt power to a level of 120 -185 KW at the TWT output followed by High Power RF plumbing components. Figure given below shows the block diagram of high power chain.

High Power RF stage consists of:

Traveling Wave Tube (TWT) Ferrite Circulator Dual Directional Coupler (DDC) High Power dummy load Wave guide channel Wave guide switch

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Control i/p from CPC

RF IN

TWT drive MONITOR

To CPC for RF drive fail

To TWT i/p

To SSPA i/p

RF DRIVER

Figure 12: Block diagram of High power microwave stage

Traveling Wave Tube (TWT)

TWT is available in three different constructs, these are listed here:

1. Helix TWTs: These amplify relatively to low power levels, but it provides a very wide bandwidth, both in octave and multioctave.

2. Ring Loop / Ring Bar TWTs: These amplify at relatively high power levels, and provide a wideband, that is of 25 % of bandwidth.

3. Coupled Cavity TWTs: This TWT in family of TWTs provides highest amplified power levels. It has relatively narrower bandwidth that is 10% to 15 % of bandwidth.

TWT is the main power amplifier used in the transmitter. A coupled cavity TWT type is selected for this transmitter.

The collector in the TWT is further divided as:

Ground collector Depressed collector Single stage depressed collector Double depressed collector Multi stage depressed collector

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Figure 13: TWT power supplies connection diagram

Ferrite circulator

Ferrite circulator is used to protect the microwave tube against failure / damage due to reflected power in case of excess VSWR at Antenna input port. The Four port Ferrite circulator type is used as an isolator.

Dual Directional Coupler

High Power Dual Directional Coupler (DDC) is used for measuring the Transmit Power and reflected power. If reflected power exceeds the specified limit of 2:1 VSWR, video signal is generated to cut-off the RF drive through control and protection unit.

High power dummy load

High power dummy load is used to test the transmitter without connecting the antenna during standalone testing.

Wave-guide Channel

To connect all the components in the required form, flexible sections, E-bends, H-bends and straight sections are used. Standard W/G sections are being used for this purpose.

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-600

+800

RF IN RF OUT

LIQUID COOLING

-45kV,5kW

33kV,18kW

3kV,ION PUMP

-10V,10A

Microwave Channel (High Power)

Figure below shows the schematic diagram of the microwave channel. The microwave channel consists of high power amplifier using TWT amplifier and high power RF plumbing components.

Figure 14: High power microwave channel

Antenna channel matching requirements

Mismatch in the antenna channel, being the load of the transmitter, significantly decides of VSWR as seen from the TWT output. According to the Antenna System requirements, matching of the antenna channel at the transmitter output should be equivalent to VSWR prescribed margin in frequency range of S band in which the radar operates. It seems to be difficult to satisfy, because the TWT should operate at VSWR <1, the isolator of proper directivity has to be applied in the wave-guide channel.

Power Variation along RF line

Max. RF power losses along the output wave-guide channel altogether with VSWR losses taken into consideration, were calculated for operation on the antenna. Assuming that RF pulse power at the TWT output is equal 120 kW (min), RF pulse power at the transmitter output should be contained within in the range of 90 kW in the case of operation on the antenna. Figure given above shows the power variation along the RF line.

Solid State Power amplifier

This Solid-state power amplifier is used during the fail-safe mode. A power of 1.5 KW peak at required duty is delivered to antenna through Solid State Power Amplifier when liquid cooling fails. This Mode is selected by the operator.

Ion Pump Supply

Ion pump supply is a source of positive voltage about 3.3kV, intended to supply TWT ion pump, which is integral part of the TWT to maintain the vacuum level inside TWT.

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Transmitter Cooling

This system is a forced liquid-to-air type, used for cooling sub systems of the F-Band Transmitter. The primary coolant used for circulation through this transmitter heat loads is Dematerialized water / Glycol for operation from required range of temperature. The transmitter employs liquid cooling for TWT, high power circulator, RF dummy load and high voltage inverter and forced air-cooling for all other sub-assemblies. Independent of air-cooling, a dry air with low dew point and dust particles should be applied for wave-guide pressurizing and for TWT. General design of the cooling is worked out in such a way that the temperature rise for outlet coolant is around 10C as compared to the inlet coolant.

CURRENT STATUS

BEL anticipates a requirement for 100 ROHINI radars. BEL delivered the first ROHINI radar to the Indian Air Force on August 6, 2008. Around 20 radars can be manufactured annually.

Since then, the IAF has ordered over 30 more radars after evaluation and also ordered a modernization program for existing subsystems.

The REWATI radars add two axis stabilization and extra naval modes. Two of them were ordered by the Indian Navy for their P-28 Corvette program.

Additional orders are also to be expected from the Indian Army if they order the Akash Missile System as well as a 3D CAR or 3D TCR or 3D tactical control radar.

Overall, the 3D CAR program highlights India and DRDO’s success in developing and manufacturing a modern 3D radar.

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CONCLUSION

My experience of six weeks at BEL Ghaziabad was a truly educative and inspiring one. Getting the opportunity to get to know the roots of how an industry functions and how the various concepts of electronics and communications engineering are put to use practically, was something I was very keen on observing.

Through studying the basic concepts of RADAR as well as CAR, I can conclude that it is truly a marvel of engineering, which has an array of advantages and uses.

ADVANTAGES OF CAR

S band operation. Medium range 3D surveillance. Surveillance range up to 180 km. Covers elevation up to 18 km in height. High altitude deployability. Deployment in less than 20 minutes. 150 targets in TWS. Array of ECCM features. Integrated in IFF. Capable of detecting low altitude targets and targets flying at supersonic speeds up to Mach 3. Frequency agility and jammer analysis.

Thus, keeping the profile of BEL Ghaziabad as well as the sectors it caters to, I can conclude that CAR is a genuine ‘wave of the future’ in defense systems and security purposes.

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LIST OF FIGURES

S.NO TITLE PAGE NO.1 Block diagram of radar 222 Block diagram of ROHINI TRANSMITTER 263 Rack structure of transmitter 284 Block diagram of transmitter 305 Control rack 306 Block diagram of CPC 327 High voltage rack 338 Block diagram of FDM 349 FDM 3410 Block diagram of microwave rack 3511 Block diagram of RF driver 3612 Block diagram of high power microwave stage 3713 TWT power supplies connection diagram 3814 High power microwave channel 39

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LIST OF TABLES

S.NO TITLE PAGE NO.1 9 units of BEL all over Inia 42 Customers and products supplied 11

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REFERENCES

This project report has been made using the material extracted from the following sources:

1. Communication Systems by Simon Hayin, Fourth Edition

2. Modern digital and analog communication systes by B P Lathi and Zhi Ding, Third Edition

3. www.wikipedia.org

4. Google Image search

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