D ESARROLLO DE LAS I TERACIONES

40

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.

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.

41 Salient features Radar are:

1. 3D Surveillance Radar 2. S-BAND

3. Capable of Track While Scan (TWS) of airborne Targets upto 150 Kms 4. Coherent TWT based Transmitter

5. 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.

This designed Radar has the following subsystems:

1. Multi-beam Antenna system 2. Transmitter

3. Receiver

4. Signal Processor 5. Radar Console 6. Data centre

7. Mobile Power Source 8. 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.

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

42 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.

43

TRANSMITTER

44

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.

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

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