A variety of sensors and weapons are on offer to quell threats of submarine attacks
Any captain of a warship will say that the threat he most fears is that of a stealthy submarine lurking underwater, observing and later unleashing its firepower of torpedoes or anti-ship missiles. Submarines are particularly dangerous in tropical waters such as the Indian waters where thermoclines can reduce SONAR detection ranges, and it thus needs the combined efforts of a spectrum of sensors and weapons deployed from surface ships, helicopters, aircraft and UAVs.
Hull Mounted Sonars are fitted to the Hull of the Warship and can be operated round the clock without requiring launch time. Although they are usually larger, can be high powered, their performance is somewhat restricted by the ship’s own noise and by the fact that they operate at a constant depth. They also have higher Electromagnetic Interference/ Electromagnetic Compatibility (EMI/EMC) requirements to be able to work with the ship’s electronics. The Naval Physical and Oceanographic Laboratory (NPOL) has built the Hull Mounted Sonar Array-Next Generation (HUMSA-NG) with Bharat Electronics Limited (BEL), which has produced it.
It is an Active cum Passive Integrated Ship Sonar system which can transmit and receive sound waves or listen to enemy sound signatures. It equips the latest Indian Navy frontline warships including P-17 frigates, P-15A destroyers and P-28 corvettes. HUMSA-UG is an upgrade of the legacy HUMSA sonars by adding new receiver electronics and an ultra-cool power amplifier with an aim of reducing the maintenance by addressing the obsolescence issues. The lab also developed a compact integrated sonar system to equip vessels of low tonnage such as patrol vessels and coastal vessels. Thales has in its portfolio the BlueWatcher compact low medium frequency active passive hull mounted sonar for small vessels, corvettes, light frigates. It is reported to have good detection capabilities in high noise environments due to wideband operation and narrow beamwidth. It is also capable of operating in a multi-static mode with a variable depth sonar or dipping sonar to arrive at better target location. Atlas Elektronik Hull-Mounted Sonar (HMS) systems ASO 713/723 is marketed as a solution for blue water and littoral detection capabilities.
Towed Array variable Depth Sonar is the most important ASW sensor on a surface ship. Although it takes time to launch, it offers advantages of reduced interference from the ship as it operates at a distance from the ship and at different depths, enabling it to operate in optimal water conditions. The Indian Navy has procured six Atlas Elektronik ACTAS for its three Talwar class frigates and three Delhi Class destroyers with an option of 10 more produced under licence by BEL.
The Defence Acquisition Council (DAC) recently cleared nine more such systems. It is also looking for additional systems to equip future warships. Thales’ offering of the CAPTAS-1 low frequency active and passive variable depth sonar is capable of deep water operation with low frequency, long pulses and shallow water operation due to bottom safety. The new Human Machine Interface provides 3D analysis and chart overlay improving situational awareness.
NPOL has been involved with towed array sonars for some time with the NAGAN technology demonstrator project. It is now pursuing the development of the Advanced Light Towed Array Sonar (ALTAS) along with BEL. The requirement for ALTAS is going to be huge as newer ships are built and in-service ones line up for midlife refits, presenting an opportunity for both locally and externally developed hardware.
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