If you have watched some of the widely acclaimed submarine movies such as U-571, Das Boot or The Hunt For Red October, you’ll recall how navy personnel manning underwater war machines have used sonar technology to navigate and detect objects on or under the surface of the water, such as other vessels. Sonar, an underwater equivalent of radar, is used to find and identify objects in water. It is also used to determine water depth and is applied to water-based activities because sound waves attenuate (taper off) less in water as they travel than do radar and light waves.
The modern anti-submarine warfare demands sensor deployment from surface, sub-surface and air. Gone are the days when sonar equipment for the Indian Navy used to be imported from Russia, Germany and Poland. In the last few years, this has become a key area of focus for the Defence Research and Development Organisation (DRDO), the endeavour being to make the country self-reliant in this technology.
A key DRDO laboratory located in Kochi, called the Naval Physical and Oceanographic Laboratory (NPOL), is taking rapid strides in the design and development of underwater surveillance systems. Commencing with advanced panoramic sonar hull mounted (APSOH) in 1983, NPOL has delivered several sonar systems, such as Panchendriya, Humsa, Mihir, etc, which have been fitted on to submarines, surface ships and airborne platforms of Indian Navy. The operational utility of these systems has provided impetus for further improvement and development of new configurations of underwater systems in tune with global standards, DRDO officials inform.
The core competence of NPOL is in the areas of oceanography, electro-acoustic transducers, signal processing and systems engineering. Over the years, the institute has established several infrastructure facilities for carrying out defence R&D activities related to sonar systems. It owns a marine acoustic research vessel named as INS Sagardhwani. The vessel is run and maintained by the Indian Navy for DRDO and based at Southern Naval Command, Kochi.
This ship has got many special facilities for conducting underwater ocean environmental and acoustic experiments both in shallow and deep waters. Modern equipments are fitted on-board in order to pursue research in oceanography and acoustics. The ship’s laboratories house all scientific equipment to make high resolution oceanographic and acoustics measurements at the sea. The ship can moor oceanographic and acoustic buoys in shallow and deep waters.
For the uninitiated, sonar is an acronym for sound navigation and ranging. The principle involves