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Rising challenges
ASW capability and underwater surveillance

During conflict situation the Oceans are likely to be infested with submarine killer munitions and the navies world over are adopting latest measures to counter those threats and protect own submarines while at the same time find ways to locate enemy submarines.

The anti submarine warfare is getting complex and more challenging day by day and the rival navies are devising new ways to keep the rival submarines at arms length. Since the submarines have a long reach and are potential destroyers the navies must find ways to locate and hit them before they are able to hit at own target.

Since the technology of undersea warfare has entered the fourth generation, the navies lacking them will find themselves overpowered by the rival forces. Under this warfare the experts have placed emphasis on Information Operations as a key capability and evolving mission to conduct fourth generation Under Sea Warfare.

As the anti submarine warfare is getting more and more complex the technologically more advanced nations will now exploit the fourth generation ASW techniques, though they have also placed their eyes and ears in the skies to track the submarine movements in the high seas.

Under the Fourth Generation Warfare, the scientists are working on commanding the whole electromagnetic spectrum (EMS) of the sea, but the anti submarine warfare is gradually shifting to the space domain and more and more nations will aim to shift their ASW base to space arena.

Advance efforts

The United States, Russia and China have been experimenting with the dedicated satellites to locate undersea disturbances for many years and are now reported to have perfected ways to detect submarines via satellite which is called the Non Acoustic Anti Submarine Warfare (NAASW).

The experts use the lasers, infrared and other detectors and synthetic aperture radar (SAR) in space as part of the NAASW activity. The satellites locate a submarine by observing subtle undersea disturbances caused by submarines and closely observe wave patterns on or both the sea surface or also detect subtle variations in ocean temperature. The Chinese have focused on maritime surveillance as top priority under their 863 State High Technology Development Plan. China has launched three Ocean Surveillance Satellites HAIYANG which will keep a regular watch over undersea movements in its maritime areas.

Since the navies under the ASW warfare creates anti access and area denial radius the under sea force’s stealth, endurance and payloads would fight from within this radius. In networked operations they can be converted into unique assets. Hence to fight effectively the undersea forces are trying to find a correct balance between the stealth and offensive effects. Efforts are being made to successfully integrate them into joint and coalition warfare in the complex and rapidly expanding information environment. For this the undersea forces will be requiring new equipments, skills and operational concepts.

The navies are now deploying sub sea sensor network to keep a tab on all categories of sub sea threats moving around. Among them the Autonomous Underwater Surveillance Sensor Network (AUSSNet) designed by L-3 Nautronix is now being used by the advanced navies.

This Network is designed for forward deployment in undersea areas. This can gather, process, store and discreetly transfer undersea surveillance data via satellite and or hydro acoustic telemetry links to land, air space or sea assets to enhance situational awareness. This can be deployed with ease for continuous undersea surveillance capability. This is a self contained sensor network which can be recovered, reconfigured and reused.

Through this, the surveillance data is acquired at low frequencies less than 500 Hz by using the acoustic line arrays deployed horizontally on the seabed in the relevant areas. The acquired surveillance data is recorded to a hard disk and the event data is acoustically transferred from the sensor nodes to an access node mounted on the sea bed, which is transmitted to the control and monitoring station.

According to the L-3 Nautronix AUSSNet can be used in littoral operations like forward-deployed intelligence, surveillance and reconnaissance (ISR), surveillance in choke points, harbor defence, support of Amphibious Landing Operations(ALO), maritime border surveillance, support of breakout operations, Littoral Anti-Submarine Warfare, Undersea force protection and critical infrastructure protection.

Protecting assets

For all the navies anti submarine warfare requires extensive undersea surveillance for harbor defence and protecting critical infrastructure. Not only the navies, the private sector also has huge assets in the sea like the oil platforms, pipelines and production facilities, which needs to be protected from the terrorists and also the State supported elements who may launch an attack even during peace time to damage the country’s economy.

The US based L-3 MariPro has developed fiber optic sensing technologies, reliable through water acoustic communications, fixed and autonomous systems and robust electro mechanical deployment packages. The US and other navies are extensively using the L-3 MariPro developed systems like the noise measurement ranges, which typically combine the acoustic tracking and communication capabilities of a tracking range with good capabilities for the measurement and analysis of radiated noise and signature measurements.

The Electronica Submarina (SAES) has developed ASW technologies with passive and active sonobuoys in new digital tools and processing in order to conform common undersea geographic plots enhancing the surface and subsurface detection capabilities.

The Sonobuoy Processing Acoustic Systems developed by SAES provides the tactical mission system and the acoustic sensor operators with the means to detect, classify, localize, and track submarines and surface ships based on analysis of acoustic signals acquired by deployed sonobuoys. The SPAS can be deployed on ships, Maritime Patrol Aircraft and the helicopters.

The Electronica Submarina has also developed SDL-AS which is a distant and elevated platform for sensors. It can be installed into a helicopter and can provide remote ASW capabilities without the need of a dedicated operator. The SDL also provides a unique, fully integrated surface/air communication and sensor processing system, designed to enhance and extend the ship acoustic sensors (ASW), the Anti Surface Warfare (ASuW) and the Anti Ship Surveillance and Targeting (ASST) mission extending ship’s horizon of Non-Acoustic Sensors (NAS).

The US Raytheon company has also developed many solutions for undersea warfare for navies of US and its NATO partners to detect, deter, and defend against a broad spectrum of threats. Raytheon has developed the most advanced, integrated undersea warfare capabilities to support combat, airborne anti submarine warfare and organic mine countermeasure missions.

Raytheon claims that it has equipped the US Navy with game changing anti submarine warfare capability with the ALFS, Airborne Low Frequency Sonar. ALFS has been rigorously deployed and tested, proving its value as the centerpiece of the Navy’s ASW mission. The ALFS is the only in-service dipping sonar with multi-frequency operation to adapt to varying environmental conditions and a rapid search rate for indentifying threats sooner over a large search area.

The Lockheed Martin has developed the Sea TALON (Tactical Littoral Ocean Network system for the ASW mission for the US Navy’s Littoral Combat Ship (LCS). Sea TALON is a unique undersea surveillance system that uses a Remote Towed Active Source (RTAS), a multi-band transducer networked with a Remote Towed Array (RTA), to provide search, detection and localization of quiet submarines in the littorals. Each array is towed by an unmanned, semi-autonomous, semi-submersible Remote Multi-Mission Vehicle (RMV), an ASW-variant of Lockheed Martin’s AN/WLD-1 Remote Minehunting System. The RMV, launched and controlled remotely from a forward-deployed LCS, will provide the Navy’s first unmanned, organic, real-time ASW capability, significantly enhancing ship and crew safety.

Indian defence scientists have also tried to catch up with the Americans and the Europeans in the ASW and has handed over the Indian Navy a system called NAGAN, which is a low frequency active cum passive towed array sonar system which has been developed by the NPOL (National Physical and Oceanographic Laboratory, Cochin) in association with the Bharat Electronics and some private sector companies.

NAGAN has replaced the French Thales supplied passive towed array sonar system. NPOL scientists claim that the NAGAN has been a major technological breakthrough, which is capable of long range detection. The NAGAN Towed array sonar system consists of a sensor array that is towed behind a submarine or surface ship. This consists of a long array of hydrophones that is trailed behind the ship using a long cable when deployed. The hydrophones are placed at equal distance on the array. This sonar is much more effective in detecting and classifying the vessels being tracked at variable depths, as noise due to turbulence of own-ship propulsion will not corrupt the signals received from the target, according to a scientist.

However, India will have to fathom many seas before it is able to elevate its ASW techniques to fourth generation level and skyrocket to the space with ASW enabled satellites.