Presentation on Transmitter of Radar Ppt

PRESENTATION ON TRANSMITTER OF RADAR

SUBMITTED BYGOVIND DAS B.TECH 4th YEAR 090103081

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.

• 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.

Transmitter • 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.

ROHINI TRANSMITTER 3-phase,400V,50Hz

3-channel liq cooling in 3-channel liq cooling out Air cooling in

ROHINI TRANSMITTER

RF out

Air cooling out BIT0 SP signals BIT1 RF PULSE Dry air

System status

PRETRG GRID PULSE

RF input

Input output diagram of Transmitter

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

• A generalized diagram here briefly explains the inputs and outputs of the transmitter.

• 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 • 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

GENERAL DESCRIPTION • 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 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 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. • 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. • 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.

THANK YOU