ARUDHA RADAR

Disclaimer: Copyright infringement not intended.

Context: The Indian Ministry of Defence (MoD) has signed a contract with Bharat Electronics Limited (BEL) for buying Arudhra radar and DR-118 RWR worth Rs 3,700 Crore for Indian Air Force (IAF).

Details: 

• Both of these contracts will be concluded under the Buy Indian-IDMM (Indigenously, Designed, Developed and Manufactured) category.

About Arudha Radar:

• MPR indigenous rotating active phased array multifunction 4D radar capable of automatic detection and tracking of aerial targets ranging from fighter aircrafts to slow moving targets.

Range: The system has an instrumented range of 400 Km and is able to detect 2sqm RCS targets as far as 300 Km in range with altitude coverage from 100 meters to 30 Kms.

Operating mode: The radar operates either in Staring or Rotation Mode.

Technologies: The following are the technologies established as part of ARUDHRA radar and it has spin-off for all future similar class of radar projects of LRDE.

• Rotating Active Phased Array
• Time synchronization of multiple receivers
• 2D Digital Beam-forming
• DBF based active array calibration
• Multi-Beam processing
• Critical real-time software and firmware
• Independently rotating IFF radar.
• Mechanical Packaging (Engineering, Thermal, etc.,)

Application Areas:

• MPR technology can be to be used for any ship borne radar applications.
• The technology will be used for mountain radar and in future family of radars of LRDE for various application.
• Presently MPR technology is used for similar class of radars for Indian Army.

What is a Radar System?

• RADAR stands for Radio Detection and Ranging System.
• It is basically an electromagnetic system used to detect the location and distance of an object from the point where the RADAR is placed.
• It works by radiating energy into space and monitoring the echo or reflected signal from the objects.
• It operates in the UHF and microwave range.

 The working of radar: it transmits electromagnetic energy in the direction of targets to observe the echoes and returns from them. Here the targets are nothing but ships, aircraft, astronomical bodies, automotive vehicles, spacecraft, rain, birds, insects, etc. Instead of noticing the target’s location and velocity, it also obtains their shape and size sometimes.

 The main objective of radar: to discover faraway targets under difficult climate conditions & determines their distance, range, through precision.

Working Principle: The radar working principle is very simple because it transmits electromagnetic power as well as examines the energy returned back to the target. If the returned signals are received again at the position of their source, then an obstacle is in the transmission way. This is the working principle of radar.

Fundamentals of Radar:

• The RADAR system generally consists of a transmitter that produces an electromagnetic signal which is radiated into space by an antenna.
• When this signal strikes an object, it gets reflected or reradiated in many directions.
• This reflected or echo signal is received by the radar antenna which delivers it to the receiver, where it is processed to determine the geographical statistics of the object.
• The range is determined by calculating the time taken by the signal to travel from the RADAR to the target and back.
• The target’s location is measured in angle, from the direction of the maximum amplitude echo signal, the antenna points to. To measure the range and location of moving objects, the Doppler Effect is used.

The Doppler effect or Doppler shift is the apparent change in frequency of a wave in relation to an observer moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842.

The essential parts of this system include the following:

• A Transmitter:It can be a power amplifier like a Klystron, Travelling Wave Tube, or a power Oscillator like a Magnetron. The signal is first generated using a waveform generator and then amplified in the power amplifier.
• Waveguides:The waveguides are transmission lines for transmission of the RADAR signals.
• Antenna:The antenna used can be a parabolic reflector, planar arrays, or electronically steered phased arrays.
• Duplexer:A duplexer allows the antenna to be used as a transmitter or a receiver. It can be a gaseous device that would produce a short circuit at the input to the receiver when the transmitter is working.
• Receiver:It can be a superheterodyne receiver or any other receiver which consists of a processor to process the signal and detect it.
• Threshold Decision:The output of the receiver is compared with a threshold to detect the presence of any object. If the output is below any threshold, the presence of noise is assumed.

Types of Radar:

Bistatic Radar: This type of radar system includes a Tx-transmitter & an Rx- receiver that is divided through a distance that is equivalent to the distance of the estimated object. The transmitter & the receiver are situated at a similar position is called a monastic radar whereas the very long-range surface to air & air to air military hardware uses the bistatic radar. 

Doppler Radar: It is a special type of radar that uses the Doppler Effect to generate data velocity regarding a target at a particular distance.

Monopulse Radar: This kind of radar system compares the obtained signal using a particular radar pulse next to it by contrasting the signal as observed in numerous directions otherwise polarizations.

Passive Radar: This kind of radar is mainly designed to notice as well as follow the targets through processing indications from illumination within the surroundings. These sources comprise communication signals as well as commercial broadcasts.

Instrumentation Radar: These radars are designed for testing aircraft, missiles, rockets, etc. They give different information including space, position, and time both in the analysis of post-processing & real-time.

Weather Radars: These are used to detect the direction and weather by using radio signals through circular or horizontal polarization.

Mapping Radar: These radars are mainly used to examine a large geographical area for the applications of remote sensing & geography.

Navigational Radars: Generally, these are the same to search radars but, they available with small wavelengths that are capable of replicating from the ground & from stones. These are commonly used on commercial ships as well as long-distance airplanes.

Pulsed RADAR: Pulsed RADAR sends high power and high-frequency pulses towards the target object. It then waits for the echo signal from the object before another pulse is sent. The range and resolution of the RADAR depend on the pulse repetition frequency. It uses the Doppler shift method.

Pulse-Doppler: It transmits high pulse repetition frequency to avoid Doppler ambiguities.

 Moving Target Indicator: It transmits low pulse repetition frequency to avoid range ambiguities. In an MTI RADAR system, the received echo signals from the object are directed towards the mixer, where they are mixed with the signal from a stable local oscillator (STALO) to produce the IF signal.

Continuous Wave: The continuous wave RADAR doesn’t measure the range of the target but rather the rate of change of range by measuring the Doppler shift of the return signal.

Applications: 

Military:

• In air defense, it is used for target detection, target recognition, and weapon control (directing the weapon to the tracked targets).
• In a missile system to guide the weapon.
• Identifying enemy locations on the map.

Air Traffic Control:

• To control air traffic near airports. The Air Surveillance RADAR is used to detect and display the aircraft’s position in the airport terminals.
• To guide the aircraft to land in bad weather using Precision Approach RADAR.
• To scan the airport surface for aircraft and ground vehicle positions

Remote Sensing: It can be used for observing whether or observing planetary positions and monitoring sea ice to ensure a smooth route for ships.

Ground Traffic Control: It can also be used by traffic police to determine the speed of the vehicle, controlling the movement of vehicles by giving warnings about the presence of other vehicles or any other obstacles behind them.

Space:

• To guide the space vehicle for a safe landing on the moon
• To observe the planetary systems
• To detect and track satellites
• To monitor the meteors

PRACTICE QUESTION Q)  What do you mean by the term Radar? What are its various applications? (150 words)

 

https://www.thehindu.com/news/national/defence-ministry-signs-3700-crore-contracts-for-radars-radar-warning-receivers/article66654472.ece