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The Sonar market in India 'hots' up

Saurav Jha @SJha1618

Updated: August 11, 2014, 12:45 PM IST
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Defence procurement in India has often been characterized by the need to make a decision between importing an off-the-shelf system on operational grounds and waiting for a home grown system to complete development. Sonars for the most part has been an area where such decisions have been easier to make with the Indian Navy(IN) mostly opting for indigenous systems developed by DRDO' s underwater sensor laboratory the Naval Physical and Oceanographic Laboratory (NPOL), Kochi. Recently however, time lags in a few segments of this critical technology area have led IN to explore foreign options even as the indigenous system is being progressed. A key example would be IN's move to source active towed array sonar (ATAS) units from overseas as an urgent anti-submarine warfare (ASW) requirement given that NPOL's program for that is still work in progress. Nevertheless given operational security considerations and India's overall capability in this sphere, domestic development will continue to be pursued even as some systems are brought in for more immediate warfighting needs.

Given the Pakistani Navy's (PN's) acquisition of air independent propulsion (AIP) equipped Agosta-90B submarines and the Chinese Navy's(CN's) deployment of Shang Class nuclear attack submarines in the India Ocean Region (IOR), ASW has obviously emerged as a major priority area for IN. More so because its own submarine strength hasn't been the greatest, leading to a major focus on surface ship based ASW. For this purpose both indigenous hull mounted sonars (HUMSA) as well as passive towed array sonars(PTAS) sourced from Thales currently fielded on IN ships have been deemed inadequate in light of the contemporary submarine classes being deployed by IN's potential adversaries and the proliferation of heavyweight torpedoes (HWT) in their arsenal. Of particular concern would be Russian origin HWTs fielded by the Chinese of the Type 53-65KE family.

As such IN has felt the need to gain an edge over enemy submarines by detecting them beyond the range of their HWTs. PN and CN submarines do field anti-ship missiles that can be fired from much further but it is actually the HWT which is a deadlier prospect for ships given their stealthiness, warhead size and point of impact. To that end IN has sought to induct low frequency ATAS which also have passive modes of operation.

Any towed array sonar system is essentially a series of hydrophones trailing behind the ship using a winch and cable system with the hydrophones placed at an equal distance on the array. The cable configuration keeps the array's sensors at a distance from the ship's own noise sources, greatly improving the signal-to-noise ratio, and thereby increasing efficacy in detecting and tracking quiet, low noise-emitting submarine threats, or seismic signals. ATAS also yields superior resolution and range compared to HUMSA type sonars.
NPOL has pursued ATAS technology for some time now but was unable to make the NAGAN low frequency active-cum-passive TAS pass muster with IN which rejected it during user evaluation trials (UETs) in 2009. NAGAN wrapped up as a technology demonstrator project in 2012, subsequent to which NPOL began developing the advanced light towed array sonar (ALTAS) which is currently undergoing tech trials on INS Sagardhwani and is expected to be ready in a couple of years with Bharat Electronics Limited (BEL) as systems integrator along with L&T, Uniflex Cables and Keltron.

In the meantime, IN has pushed forward on the import option based on a RFP it issued in 2009 for six off the shelf ATAS to L-3 communications, Thales and ATLAS Elektronik (AE). While the competitive trials were fraught with controversy especially with respect to the claims made by all three companies, it seems that AE with its ACTAS offering has now won the competition for the ATAS emerging as the lowest cost bidder for this program with a reported unit cost of Rs 50 crores.

According to AE, the 70 mm ACTAS which it is also supplying to the Thai Navy, 'operates in the low-frequency range from about 2 kHz and permits observation of the sea space at ranges considerably above 60 kilometres, depending on the propagation conditions of the water.' Sixty kilometres is well outside the engagement envelope of most HWTs. ACTAS can operate in deep as well as shallow waters and obviously allows variable depth operations like any other ATAS. AE also touts the fact that ACTAS has an automatic torpedo warning system that works continuously in the background and automatically generates alerts. The first six units supplied by AE's facilities will equip the Delhi and Talwar class ships with ten more to be manufactured in India under transfer of technology (ToT) at BEL which will be deployed on the Kamorta, Shivalik and Kolkata classes of ships. The final clearance from the Ministry of Defence (MoD) for this purchase however hasn't been accorded in light of the allegations of corruptions that surrounded this particular tender.

Even as the status of the ATAS tender remains unclear, IN has however managed to import some 12 sets of side scan sonars from US based EdgeTech, which was awarded the contract after a competitive trial with another side scan sonar manufacturer. Edgetech's littoral mine countermeasure sonar (LMCS) System procured under this deal has come with dual detection and classification capabilities configured to work with SeeByte's 'SeeTrack' Automated Target Recognition (ATR) software. The LMCS are part of IN's Pondicherry class Minesweeper upgrade program as well as possibly for the four Abhay class corvettes in its fleet. According to EdgeTech, LMCS features dynamically focused transducers and multi-pulse side scan sonar technologies to provide 'exceptional swath coverage and ultra-high-resolution imagery in demanding operational environments.' It is also equipped with 600/1600kHz dual frequency sonar which allows operators to 'locate, classify, mark and record mine-like objects and underwater terrain features while providing real-time sonar images.'

IN is also running tenders for 12 units of a new torpedo defence suite (NTDS) which will consist of a sonar, decoy and a fire control system and for specialized sonars to be mounted on the 16 new littoral ASW craft it is planning to induct. There is also a tender for ATAS to equip some eight kilo class submarines in its inventory. Now while the urgency to bring in new ATAS for surface ships is understandable, IN obviously has to keep the perspective on indigenous development overall. Especially since the indigenous route has yielded good returns in sonar technology over the years.

Today, most Indian frontline combatants feature HUMSA or its 3rd generation variant the HUMSA-NG as their chief on-board acoustic sensor and it is accepted that these work particularly well in the higher thermoclines of the IOR. HUMSA NG which is a technology upgrade of HUMSA with lower frequency transducers and state-of-the-art electronics power PC processors and SHARC signal processing boards was developed in four years flat in response to naval staff qualitative requirements. Three HUMSA export variants have even been sold to Myanmar. IN is also very happy with the USHUS hydro-acoustic sensor and CCS-MK communications systems NPOL has developed for the kilo class submarines and has placed orders for four more sets of USHUS sonar with BEL in addition to the five already procured. The Tadpole sonobuoy system developed by NPOL and built by Tata Power SED has also found favour with IN.

What all this shows is that NPOL has very credible capability in areas where it has worked for a while and it is only a matter of time before it crosses the threshold in others as well. It is important to note this because an attempt to wantonly disparage Indian sonar capabilities is underway in some sections of the press that betrays suspicious intent. And this is happening at a time when IN has tenders out for systems that are all being developed indigenously anyway.

For instance an indigenous anti-torpedo defence system called Mareech is undergoing UETs on INS Ganga and Gomti and NPOL has been expecting formal orders for the same. In light of this it is unclear as to why IN is running an open tender for a similar system in the form of the NTDS. In the case of the littoral ASW craft as well, NPOL has come up with the Abhay sonar which is currently undergoing tech trials on INS Agray yet there are reports which are claiming that 'IN may be looking abroad for this segment.' The picture at the moment is rather murky and some clarity from both IN and DRDO would be welcome.

In any case sonars like radars are an area of technology where self-sufficiency is the key for OPSEC reasons. And it is not as if foreign systems are a panacea anyway. It could be said that new generation low frequency ATAS are not that mature anywhere yet especially given that making these sonars compact while operating in the lower frequency range are design goals that pull in opposite directions. Nevertheless for ALTAS, NPOL is working intensely in the field of electro-hydraulic winches, high density underwater connectors, electro-opto-mechanical tow cables, acoustic sensors, electronic cabinets, high performance polymer strength members and the like to make it lighter than other ATAS out there. With a future requirement of more than 80 ATAS units, this is one domain that is likely to be fiercely contested between Swadeshi and Videshi.

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First Published: August 11, 2014, 12:45 PM IST

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