RADAR TRANSMITTER

1. SIX-WEEKS INDUSTRIAL TRAINING
(JUNE-JULY2012)
AT
BHARAT ELECTRONICS LIMITED
(BEL) GHAZIABAD
ON
“RADAR TRANSMITTER”
SUBMITTED BY
H I T E S H M I T TA L
101005021

2. CONTENTS
 Bharat Electronics Limited –An Overview
 Rotation
 Introduction to RADAR
 Its block diagram
 Transmitter
 Its mechanical description
 Its general description

3. 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.

4. 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.

5. 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.

6. 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.

7. PROJECT
1)ROTATION(brief sight to
various departments)
2)RADAR
TRANSMITTER

8. 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.

9. 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.

10. 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.

11. ROTATION
WORKS ASSEMBLY
• Its main function to assemble various products
,components and instruments in particular
procedure.

12. ROTATION
QUALITY CONTROL WORKS
• Its main function to ensure the quality of the
product.
• It inspects all items manufactured in the factory
 After mistake is detected –
i. Observation is made.
ii. Object code is given.
iii. Division code is given
iv. Change code is prepared
v. Recommended action is taken

13. I
N
T
R
O
D
U
C
T
RADAR
I
O
N

14. 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.

15. Sign conventions
The Doppler frequency is negative (lower
frequency, red shift) for objects receding from the
radar
The 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
Red: Receding from radar
Blue: Toward radar

16. BLOCK DIAGRAM

17. 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.

18. 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.

19. 3-phase,400V,50Hz
3-channel liq cooling in
3-channel liq cooling out
ROHINI RF out
Air cooling in
Air cooling out TRANSMITTER
SP signals System status
BIT0
BIT1
RF PULSE Dry air
PRETRG
GRID PULSE
RF input
Input output diagram of Transmitter

20. OPERATION MODES OF
TRANSMITTER
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 solid state
Power amplifier when liquid cooling fails.
Modes are selected by the operator.

21. MECHANICAL DESCRIPTION

22. 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

23. 1.)CONTROL RACK

24. 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.

25. 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.

26. 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.

27. 3.)MICROWAVE RACK

28. 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

29. 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.

30. MICROWAVE RACK
 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

31. 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.

32. 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.

33. GENERAL DESCRIPTION
SSPA
W/G
RF DRIVER TWT COUPLER SWITCH
TO
ANTENNA
FWD AND
RFLECTED
PWR MONITOR
LIQUID COOLING
FIL., GRID, CATHODE,
COLLECTOR SUPPLY

34. 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.

35. 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.

36. GENERAL DESCRIPTION
 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.

37. 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.

38. GENERAL DESCRIPTION
 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.

39. THANK YOU