six weeks industrial training
DESCRIPTION
RADAR TRANSMITTERTRANSCRIPT
ATBHARAT ELECTRONICS LIMITED
(BEL) GHAZIABADON
“RADAR TRANSMITTER”
S U B M I T T E D B YH I T E S H M I T T A L
1 0 1 0 0 5 0 2 1
SIX-WEEKS INDUSTRIAL TRAINING
(JUNE-JULY2012)
CONTENTS
Bharat Electronics Limited –An OverviewRotationIntroduction to RADARIts block diagramTransmitterIts mechanical descriptionIts general description
BEL-An Overview
It was founded in 1954.Founded as a public Sector Enterprise under the
administrative control of Ministry of Defence as the fountainhead to supply and manufacture electronics components and equipments.
Today BEL’s infrastructure is spread over nine locations with 29 production divisions having ISO 9001/9002 accredition.
BEL-An Overview
CORPORATE MOTTO-“Quality,Technology and Innovation.”
• CORPORATE MISSION-• To be the market leader in Defence
electronics and in other chosen fields and products.
BEL-An Overview
CORPORATE OBJECTIVES-To become a customer driven company.To achieve growth in operation commensurate
with the growth of professional electronic industry in the country.
To generate internal resources for financing the investments.
In order to meet the nation’s strategic needs,to strive for self reliance by indigenization of materials and components.
BEL-Ghaziabad Plant
Over the years the unit has successfully manufactured a wide variety of equipment needed for defence and civil use.
It enjoys a unique status as manufacture of IFF systems needed to match a variety of primary radars.
The operations at BEL Ghaziabad are headed by General manager with Additional/Deputy General Manager heading various divisions.
1)ROTATION(brief sight to various departments)
2)RADAR TRANSMITTER
PROJECT
ROTATION
TEST EQUIPMENT SUPPORT (TES)• Develops technical supports to other
departments. This includes :-Handling requests for equipments from other
departments.Storage of rejected equipments.Approval of equipments to be purchased.• Repair of equipment in case of failure.• Maintenance of equipments.
ROTATION
AUTOMATION TEST EQUIPMENT (ATP)
1) Component testing-gives faults of various discrete components of a PCB.
2) Integrated Circuit-tester tests various IC’s.3) Functional testing-compares output to
decide whether the function is being performed to the desired accuracy level.
ROTATION
PCB FABRICATION
• It is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non conductive substrate.
ROTATION
WORKS ASSEMBLY
• Its main function to assemble various products ,components and instruments in particular procedure.
ROTATION
QUALITY CONTROL WORKS • Its main function to ensure the quality of the
product.• It inspects all items manufactured in the factoryAfter mistake is detected –i. Observation is made.ii. Object code is given.iii. Division code is giveniv. Change code is preparedv. Recommended action is taken
RADAR
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RADAR
RADAR-Radio detection and Ranging.
FUNCTIONS Measurement of target angles as its primary
function. Measurement of Doppler velocity and
discrimination of a desired target from background noise and clutter is a prerequisite to detection and measurement.
Sign conventions
The Doppler frequency is negative (lower frequency, red shift) for objects receding from the radarThe Doppler frequency is positive (higher frequency, blue shift) for objects approaching the radar
These “color” shift conventions are typically also used on radar displays of Doppler velocity
Blue: Toward radar
Red: Receding from radar
BLOCK DIAGRAM
RADAR
Operates in S –band.Capable of track while scan (TWS) mode of
airborne targets upto 130 km.It employs multibeam coverage to in the
receiving mode to provide for necessary discrimination.
The antenna is mechanically rotated in azimuth to provide 360 degree coverage.
It is designed to play the role of medium range surveillance.
TRANSMITER
SALIENT FEATURES-
It is of coherent MOPA type.It operates in S –band using TWT as a final
amplifier.It is used to amplify low RF power 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.
Input output diagram of Transmitter
3-phase,400V,50Hz
3-channel liq cooling in
3-channel liq cooling out
Air cooling in
SP signals
Air cooling out
Dry air
BIT0BIT1
PRETRGGRID PULSE
RF outROHINI
TRANSMITTER
RF input
System status
RF PULSE
OPERATION MODES OF TRANSMITTER
a) OFF : All subsystems switched OFFb) 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 solid state Power amplifier when liquid cooling fails.
Modes are selected by the operator.
MECHANICAL DESCRIPTION
3-TRACK CONFIGURATION Control Rack Monitoring panel Control panel Synoptic panel CPC Inverter High Voltage Rack FDM (Solid state Switching) Cathode Assembly Collector Assembly Blower Unit Heater Unit Microwave Rack TWT RF Plumbing RF Drive Unit SSPA ION Pump Controller
1.)CONTROL RACK
CONTROL RACK
Control Rack provides the protection controls and indications. As mentioned before, this rack is divided in five sections according to their functions.
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.
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.
CONTROL RACK
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.
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.
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.
2.)HIGH VOLTAGE RACK
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.
3.)MICROWAVE RACK
MICROWAVE RACK
The microwave unit consists of the following functional assemblies:
1. Low power amplifier [RF drive unit]
2. High power TWT amplifier
3. RF Plumbing, Wave-guide switch & dummy load
4. Solid state power amplifier (2 kW) for low power transmission mode
5. TWT ion pump supply
6. Resistive TWT anode divider
7. Microwave power measurement circuits
8. Air cooling components
MICROWAVE RACK
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.
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.
MICROWAVE RACK
High Power RF stage consists of:
Traveling Wave Tube (TWT)Ferrite CirculatorDual Directional Coupler (DDC)High Power dummy load Wave guide channelWave guide switch
MICROWAVE RACK
A traveling-wave tube (TWT) is a specialised vacuum tube that is used in electronics to amplify radio frequency (RF) signals to high power, usually as part of an electronic assembly known as a traveling-wave tube amplifier (TWTA).
The bandwidth of a broadband TWT can be as high as one octave, although tuned (narrowband) versions exist, and operating frequencies range from 300 MHz to 50 GHz. The voltage gain of the tube is on the order of 70 decibels.
MICROWAVE RACK 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 with out
connecting the antenna during stand alone 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.
GENERAL DESCRIPTION
RF DRIVER TWT
FIL., GRID, CATHODE, COLLECTOR SUPPLY
COUPLER
FWD AND RFLECTED PWR MONITOR
LIQUID COOLING
TOANTENNA
SSPA
W/GSWITCH
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 to few W which is necessary to drive the TWT amplifier.
This is followed by an isolator. The isolator protects the transistor power amplifiers against excessive 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.
GENERAL DESCRIPTION
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.
GENERAL DESCRIPTIONControl 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.
GENERAL DESCRIPTION
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.
GENERAL DESCRIPTIONCooling 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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