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four indigenously developed SONARS inducted in indian navy
Dec 21, 2016

The Government has formally inducted four types of indigenously developed SONARS in Indian Navy that will boost its underwater surveillance capability recently. 

SONAR  is an acronym that stands for Sound Navigation And Ranging .

Kochi  based  Naval  Physical  Oceanographic Laboratory (NPOL)  of  DRDO, has  handed over  the following  four  naval systems to Indian Navy:
1.Abhay (Compact Hull-Mounted Sonar for Small Ships & Shallow Water Crafts):  Induction of Abhay (by replacing the vintage Russian sonar) enables indigenous sonar system to be installed on small ships, thereby enhancing the ASW surveillance capability of the fleet to smaller vessel, like Shallows Water Crafts, Light Frigates & Patrol Vessels, which was hitherto limited to frigates and destroyers.

  • 3 systems of Abhay are slated for installation on the Abhay Class of Ships. 

2.HUMSA-UG (Upgrade for the Hull-Mounted Sonar Array (HUMSA) Series of Sonar Systems for Ships):  It enables smooth upgrade of the capabilities of the indigenously-developed legacy Sonar System HUMSA, by drastically minimizing the existing hardware and addressing technology obsolescence issues, which is currently operational on-board on 18 ships.

  • 7 systems of HUMSA-UG are proposed for installation on the Teg Class G-Class and R-Class ships. 

3.NACS (Near-field Acoustic Characterization System (NACS) for Ship Sonars):  It provides a simple and operationally efficient means to determine the frequency-dependent 3-D transmission and reception characteristics of the hull-mounted sonar aiding in the optimum performance and maintenance of the sonar.

  • 4 systems of NACS are proposed for the Kolkata Class of Ships. 

4.AIDSS (Advanced Indigenous Distress Sonar System (AIDSS) for Submarines):  It is used to signal that a submarine is in distress and thereby enable quick rescue and salvage.  It is a life-saving alarm system designed to transmit sonar signals of pre-designated frequency and pulse shape in an emergency situation, so as to attract the attention of Rescue Vessel in the vicinity.

  • 9 systems of AIDSS are planned for the Sindhu Class Submarines (EKM Submarines). 

Induction of these Systems will increase the underwater surveillance capability of Indian Naval ships.  All these Systems are to be productionised in India.

Defence Research and Development Organisation (DRDO) has developed many systems for Indian Navy. Some of the major systems are Heavy Weight Torpedo (Varunastra), Advanced Torpedo Defence System (Mareech), Multi Influence Ground Mines, etc.

How does SONAR Works?

Sonar is simply making use of an echo. When an animal or machine makes a noise, it sends sound waves into the environment around it. Those waves bounce off nearby objects, and some of them reflect back to the object that made the noise. It's those reflected sound waves that you hear when your voice echoes back to you from a canyon. Whales and specialized machines can use reflected waves to locate distant objects and sense their shape and movement.

The range of low-frequency sonar is remarkable. Dolphins and whales can tell the difference between objects as small as a BB pellet from 50 feet (15 meters) away, and they use sonar much more than sight to find their food, families, and direction. Whales send signals out between 160 and 190 decibel, the Navy has tested its sonar signals at levels up to 235 decibel.

Sonar is based on a very simple principle--a pulse of ultrasonic waves is sent into the water there it strikes the target and get bounced back towards the source.

Sonar equipment plays a crucial role in number of project and has a vast range of practical uses. Sonar devices are used for seabed surveys, investigations that are to be done underwater and most important bathymetric seabed mapping.

The exact location of underneath object or the distance of it from the source can be calculated by measuring the time it takes for the sound to return back to the source after striking the target . We know the speed of sound in water and easily calculate the distance by simple speed formula .But keep in mind that compute the distance by multiplying the speed by one-half of the time travelled. This is what we call active sonar ranging (echolocation).


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