40. Naval Communication and Sensors

(Published Defence Security India, Aug 2014)

Introduction

A warship at sea functions like a huge sea creature in respect of a majority of its functions. For example, there is a need for a ship to see, listen, and communicate; it uses Radars, Sonars and Communication equipment for these tasks. The overall goal of the warship is to identify and eliminate the threats arising at sea, thus all the equipment on board a warship is required to function in unison to achieve this aim. Emphasis in this article would be on Communication equipment, discussion on technological aspects of Radars and Sonars would be limited to essentials only.

Communications

The first official message from a ship to a shore station, 20 miles away, was sent in 1899, the first use of radiotelephone between ships was reported in 1916. However, until the installation of superhetrodyne receivers on board ships in 1931, radio communication was considered unreliable. Radio teletypewriter transmissions between ships were carried out successfully in 1944, and the first FAX (radiophoto) transmission was that of the surrender document that ended WW II!

Navies use visual, sound, and electrical means for communications. Telecommunication includes in its ambit transmission, emission, signals, images, sounds, and intelligence information by visual, oral, wire, radio, or other electronic systems.

Radiotelephone

Ships use radiotelephony because of its ease of operation, directness, and convenience. In the navy, it is used for communication between ship-to-ship, ship-to-shore, shore-to-ship, air-to-ship, ship-to-air, air-to-ground, and ground-to-air. The most important use of radiotelephone is in short-range tactical communication.

Radio communication has become a specialized field of electronics. Naval ships toady have the ability to utilize ship-to-shore, ship-to-ship, and ship-to-air, communication circuits. Naval communication systems vary in complexity depending upon their role, compatibility, and flexibility. Due to scarcity of space on board a ship, the communication equipment is spread across the ship’s compartments; however, it is ensured that the sets are capable of operating separately as well as concurrently. Complex interconnections provide the ability of selectively switching different configurations.

Radiofrequency bands commonly used for naval communication include, very high frequency and above, high frequencies, medium frequency, low frequency, very low frequency, and extremely low-frequency.

Very High Frequency and above (30 MHZ – 300 MHZ) are only used for line of sight communication as ground range is very less. High Frequency, HF (3 MHZ – 30 MHZ), has been used by the navy since WW I. HF is used for point-to-point, ship to shore, ground to air and fleet broadcast (one way only).Medium Frequency, MF ( 300 KHZ – 3 MHZ), bands in the upper and lower portions of MF are used by the Navy for ground wave transmission, since the commercial band generally extends from 535 to 1605 kilohertz. Low Frequency, LF (30 KHZ – 300 KHZ), band has only a very small part of the radio-frequency spectrum. Low-frequency transmitting installations have large physical size and high construction and maintenance costs. However, Low-frequency waves are not so seriously affected during periods of ionospheric disturbance when communications at the high frequencies are disrupted. This makes LF useful in the northern latitudes. Very Low Frequency, VLF (3 KHZ – 30 KHZ) provides a highly reliable path for communications over and under all oceans and seas of the world. Currently all naval VLF transmitters are used for fleet communications or navigation. VLF transmission is normally a one-way transmission, a broadcast, where no reply is required. A VLF broadcast of standard time and frequency signals provides precision for the operation of single-sideband transmissions, synchronous cryptographic devices, and decoding devices. It is used as a backup to shortwave communications black out by nuclear activity, as well as in communications to satellites. Extremely Low Frequency, ELF (Up to 300 HZ), communications are used by the US Navy to send short “phonetic letter spelled out” (PLSO) messages (one way communication) from operating authorities to submarines operating at normal mission speeds and depths. ELF penetrates ocean depths to several hundred feet with little signal loss.

Wireless Link Interface Communications

U.S. Navy has already begun the deployment of wireless link interface technology on board 97 of its ships for maritime interception operations. The wireless system will allow communication directly with boarding teams several miles away. Interdiction units will be able to transmit biometrics data, scanned documents, digital photos, and emails, back to the ship using the data link. US navy has successfully tested microwave-based wireless wide-area network (WWAN) between ships to enable incorporation of Long-Term Evolution (LTE) standard, generally referred to as 4G LTE. It is a standard for high-speed communications among mobile devices, and transmits data at around 100 megabits/sec, fast enough to handle images and videos as well as voice and text. The WWAN would augment the existing satellite-based communications. The LTE network would let sailors on ships receive real-time video streaming from air nodes mounted on helicopters, which in turn would permit officers to make accurate decisions. Oceus Networks is the likely provider of the systems.

DCNS has developed SySmart, a commercial wireless communications and tracking system. It enables exchange of video, voice, and data wirelessly from anywhere on board a ship using handheld devices. Internet linked video and infrared cameras and other shipboard sensors can be accessed by the sailors. The system is built around existing Ethernet systems and other proprietary wireless networks. It has been successfully tested on French naval ships and is to be incorporated in the next generation of French submarines in 2017.

Rohde & Schwarz in Europe was commissioned to design and build a navy-wide communications network encompassing shore stations, corvettes, patrol boats, landing craft of many sizes and with diverse applications, coastal mine hunters, and maritime patrol aircraft (MPA). Tailored voice and data communications solutions have been defined for shipboard internal communications and external line-of-sight (LOS) and beyond-line-of-sight (BLOS) radio communications. A navy-wide military message handling system (MMHS) covers both strategic and tactical communications. Proprietary applications supplement the STANAG protocols to include chat and e-mail functionality. In addition, HF and VHF/UHF solutions for IP-based services have been incorporated. Different subsystems for capabilities such as telephone calls, announcements, alarms, internal tactical communications on the ship, message handling, and radio equipment have been integrated into an overall system. From a single workstation, it would be possible, to take part in the ship’s internal communications as well as in external voice & data communications and to manage & control applications and devices.

The French Navy has also selected Rohde & Schwarz to provide R&S®M3SR radio communications systems for their newest nuclear submarines. The Spanish Navy also decided to equip their latest tactical submarines with Rohde & Schwarz radio communications systems. Rohde & Schwarz also provides worldwide communications systems for different kinds of aircraft carriers. The R&S®M3SR Series4400 is used on the newest and biggest ‘aircraft carrier generation’ that the United Kingdom’s Royal Navy operates.

Vitavox have been providing the world’s largest navies with military communications equipment since 1933. The audio equipment provided by Vitavox can be used in a variety of applications, both above and below deck as well as above and below surface.

Communication Systems-Indian Navy

The Indian Navy is using  indigenous systems extensively on its warships, some note worthy systems already on board warships and scheduled for fitment on ships under production are manufactured by BEL, India they are:-

-ATM Based Integrated Shipboard Data Network (AISDN), it  is a multi-services shipboard network designed to converge all voice traffic, real time video and traditional data communications onto a single broadband infrastructure. It is a flexible, triple redundant, modular and reliable network supporting multiple services for naval ships. It integrates various equipment and systems on board namely EW Systems, Radars, Sonars, CAIO (Computer Aided Information Organization), Fire Control Systems, and a number of other equipment for Ship’s Household Data (SHHD). It integrates all sensors, weapons, and communication services onto one single broadband network. It provides integrated and simultaneous transmission of voice, video and data. It has high system capacity and flexibility and uses fiber optic cable as physical medium.

-Composite Communication System (CCS) Mk III is a new generation ATM based communication system that provides ship-to-ship, ship to shore and ship to air communication. It is designed as a voice and data integrated network providing connectivity between radio equipment and remote user onboard for accessing and monitoring and control of radio equipment. The system is highly flexible and can be configured for all classes of ships. CCS Mk III consists of Control & Monitoring Subsystems (CMS), which controls and monitors the entire network and enables operation of radios from remote positions with optimum usage of facilities. Its subsystems are:-

MF Subsystem, it has telegraphy communication and monitors maritime distress frequency.

HF Subsystem, it has long-range communication on voice, telegraphy & teletype (ship-to-shore and ship-to-ship) and receives broadcast transmissions.

VHF / UHF Subsystem, Medium range communication on voice, telegraphy & teletype (ship-to-shore and ship-to-air).

RATT Subsystem, it facilitates teleprinter & telegraphic communication from a ship via radio or land / shoreline.

-Versatile Communication System (VCS) Mk III is a versatile system designed to provide internal communication facilities and display of status of various equipment and systems onboard naval ships. The system is highly flexible and re-configurable and can be configured for all classes of ships. It provides, integrated data (Status and Control) and Voice communication from a single position on IVCS, it uses VOIP technology for Voice & Data communication, it interfaces with the ATM based integrated data network (AISDN) onboard the ship; it reduces wiring and interconnections in the system.

Sonar and Radars

The other important sensors on a warship for underwater and above water threat detection are the Sonar and the Radar. It is not intended to discuss the general technical details of such systems. However, few of the Sonars and Radars   frequently in news are being briefly described below.

-Thales Underwater Systems has developed and produced Sonar 2087.
It has been designed to be a variable depth, towed active and passive Sonar system that performs in conjunction with Sonar 2050 bow-mounted active sonar on UK’s Type 23 frigates. Digital technology in signal processing and COTS hardware has been used extensively. It is claimed that S2087 will be suitable for both, littoral environments and Deep Ocean.

-Raytheon has developed the AN/SQQ-90 tactical sonar suite for the US Navy’s DDG 1000-class multi-mission destroyer. The AN/SQQ-90 comprises of the AN/SQS-61 hull-mounted high-frequency sonar, AN/SQS-60 hull-mounted mid-frequency sonar, and the AN/SQR-20 multi-function towed array sonar and handling system.

-Atlas Elektronik will supply Active Towed Array Sonar, ATAS to the Indian Navy, which will equip the Delhi and Talwar class ships. ATAS would be subsequently manufactured in India under cooperation with BEL.

-EdgeTech, has delivered 12 advanced side scan sonar systems (mine warfare) for the Indian Navy.

-Enterprise Air Surveillance Radar (EASR) is a development program for replacement for the SPS-48 and SPS-49 air surveillance radars currently on board US Navy’s amphibious ships and aircraft carriers by the 2020. Northrop Grumman has been awarded an 18-month contract for the study of the EASR requirement. The new radar system will utilize technologies from the AN/TPS-80 Ground /Air Task-Oriented Radar (G/ATOR) program.

-Empar (European Multifunction Phased Array Radar) is a G-band, multifunction, active phased array radar being developed by Selex for the Italian Navy and French Navy. Its rotating antenna at 60 rpm provides continuous surveillance, tracking, and weapons fire control. The Empar radar system will be integrated on the Horizon frigates ordered by Italy and France and the Italian Navy’s Conte di Cavour.

-Raytheon’s AN/SPY-5 is an X-band multi-tracking, target-illuminating system for surface combatants that can simultaneously search, detect, and precisely track multiple surface and air threats. The SPY-5 is an open architecture, phased-array radar system, providing an advanced self-defense solution for small and large surface ships operating in the littorals and other maritime environments. A single radar system consists of three 120-degree beam faces providing full 360-degree azimuth coverage. The mission capabilities include low-altitude horizon search; focused volume search; surface search; missile and surface gunfire control; simultaneous threat illumination; and missile midcourse guidance and terminal homing. It is compatible with all digital combat management systems, and the radar’s range, accuracy and beam agility enable the full performance of the Evolved Sea Sparrow Missile (ESSM). SPY-5’s size, weight and overall self-defense capabilities make it equally well suited for large-deck aircraft carriers and amphibious assault ships as well as corvettes.

Indigenous Sonars and Radars with Indian Navy.

Indigenous Sonars and Radars held by the Indian Navy are manufactured by BEL. Two important Sonars manufactured by BEL are the Advanced Active cum Passive Integrated Sonar System (HUMSA NG) and the Integrated Submarine Sonar (USHUS).

-HUMSA-NG is an advanced Active cum Passive integrated sonar system to be fitted on a wide variety of Indian Navy platforms such as the Project 17, Project 15A and Project 28 class ships. HUMSA-NG is an advanced version of the existing HUMSA sonar presently fitted on P16, P15, Ranjit and Talwar Class of ships. The HUMSA (NG) is designed for enhancing the system performance, reliability, and maintainability. It is capable of detecting, localizing, classifying and tracking sub-surface targets in both active and passive modes. The system provides simultaneous long-range detection in active and passive modes. The sonar is capable of localization and automatic tracking of up to eight targets in both active and passive modes. The sonar integrates the operation of the UWT and XBT systems. The system is integrated with FCS systems such as IAC MOD ‘C and CAIO for exchange of relevant information.

-Integrated Submarine Sonar (USHUS) is used to detect, localize and classify underwater submerged and surface targets through passive listening, interception of signals and active transmissions of acoustics signals. It has both analog and digital external system interface. It is modular and rugged in design with upgradeable performance features. Its passive sonar has preformed beams in azimuth and in three vertical directions using ASICS. It can auto track six targets. Its active sonar has CW and LFM modes of transmission with three selective pulse widths, high source level, low frequency planar transducer array & complex demodulation, replica correlation for Doppler and range estimation. Its intercept sonar can provide early warning long range target detection, all round coverage in three bands, FFT, and Spectral processing. The underwater communication system has multiple mode acoustic communication in dual frequency to meet NATO and other requirements, voice, telegraph, data, and message modes of operation. Its obstacle avoidance sonar is a high frequency short range sonar with rectangular transducer array and its transmission covers three sectors of 30° each.

Some of the indigenous Radars manufactured by BEL, India are-

-L- Band Surveillance Radar, RAWL02 Mk-III, is long-range L band surveillance radar for detection of air and surface targets. It has a roll and pitch stabilized antenna platform, Synthesizer controlled transmitter with TWT amplifier, state of art video extractor track management system based on COTs technology, low noise receiver combined with split pulse and matched dynamic range compression, ECCM capability and a range of 270 Km.

-3D Surveillance Radar, REVATHI,  is a state-of-the-art, S-band, Track-While-Scan (TWS) radar designed to effectively play the role of a medium range surveillance radar mounted on a stabilized platform for detection of air and surface targets. It has ECCM features, integrated IFF Mk XI , stabilization against roll & pitch, and remote transmission of data of tracks & plots over LAN for interface with external systems.

-Active & Passive Radar for Navigation & Attack (APARNA), is designed to detect surface targets, furnish target data to weapon computer for missile firing at these targets in the autonomous mode from the ship. The radar system is provided with two transmitter–receiver channels i.e. the first or main channel and the second or navigational channel. The two channels differ in transmitter peak power, pulse width etc.

Consolidated Antennas and Sensors

Communication technology developments to provide ever-increasing requirements of multiple bands and bandwidths, foresee a need for large rotating antennas. These pose several problems on board warships like space availability, electromagnetic interference and increase in ships radar signature. The trend is tilting towards development of single unit consolidating antennas and sensors. Thales Netherlands is developing its integrated sensor and communications suite, which will house radio and data-link communication systems, radar and electro-optical subsystems and IFF in a single unit. The US Navy has awarded 18 contracts to develop integration and management technology for radio frequency radar and communications functions. The objective of the advanced multifunction radio frequency concept is the integration of radar, electronic warfare and communications into a common set of apparatus with signal and data processing, signal generation and display hardware.

Thus from the above it can be appreciated that the field of sensors for utilization on a warship is an ever expanding one, with new features and capabilities adapted from the commercial world being added practically every hour. To say the least the features and capabilities of various war ship sensors by end of this decade are going to be phenomenal.

39. Midget/Mini Submarines and AUVs – Force Multipliers for Littoral Defence of India

(Published Defence ProAc Biz News Jul-Aug 2014)

“…the very shallow water (VSW) region is a critical point for our offensive forces and can easily, quickly and cheaply be exploited by the enemy. The magnitude of the current deficiency in reconnaissance and neutralization in these regions and the impact on amphibious assault operations were demonstrated during Operation Desert Storm.”

Maj. Gen. Edward J. Hanlon Jr., Director of Expeditionary Warfare, Sea Power, May 1997

 

Confined sea spaces, lesser depths, heavy traffic, threats due to lurking quiet diesel submarines, coastal missile batteries, swarms of armed boats, deployed mines and threats from the air, severely compromise a blue water navy’s ability to execute manoeuvre in littorals. The definition of a littoral region encompasses waters close to the shores as well as greater than 50 nm at sea. The Indian Navy, like all the other blue water navies has not been fundamentally positioned for close combat encounters. It is has generally been expected that sea warfare would have standoff distances of at least 50/60 km if not more between adversaries   (outside range of torpedoes and guns). If Carrier groups and anti ship cruise missile (ASCM) cruisers are deployed, the standoff can be up to a couple of hundred miles (ASCM and Air craft limits). However today littorals present an inevitable close quarter engagement situation with Carrier Strike Group (CSG) remaining well clear of coastal missile batteries and aircraft operating from shore based airfields.

Littorals have withered away the advantage of the CSG and the big ships, as manoeuvring in close quarters is not feasible any more. The lighter ships would have to fight in the littorals with a much larger risk of attrition from the diesel electric submarines, midgets, mines, swarm of boats and shore based assets. The littorals are confined zones with reducing depths and a very adverse sensor environment. This has drastically compressed reaction times leading to requirements of great agility for the men of war.

A worthy defender is always considered to be in an advantageous position in the littorals, because of the intrinsic knowledge and experience in operating in his home environment. It constitutes what the US DOD calls an access denial area likely to impinge upon the US national interests. In the Vision 2004 document this has been articulated as “To win on this 21st Century battlefield, the U.S. Navy must be able to dominate the littorals, being out and about, ready to strike on a moment’s notice, anywhere, anytime.”

Indian Navy has identified, in all probability, areas in Arabian Sea, Bay of Bengal and Indian Ocean where, should a contingency arise, it may have to engage in littoral conflicts singly, or in concert with coalition of navies. Post  26/11, realising the vulnerability of the coasts to attack by terrorists, the Government of India has initiated efforts to tighten its coastal security. As to the plans of defending own littorals against a formidable expeditionary force, nothing much is known in the open domain, in all likely hood it remains a simplistic defensive model due to insufficient focus and inevitable funding. The fact remains that ‘ocean rim state navies’ today are focussing more on littoral capability than building a blue water navy. Indian Navy has to consider the littoral capability seriously whilst modernising and achieve a balance between offence and defence, depending upon its current and future threat perceptions. The blue water force has to have an embedded littoral component force so that the IN can operate in littorals far away from her homeports without worrying about security of its ports.

The aim of this article is to highlight the importance of the midget/mini submarines as well as unmanned underwater vehicles in the defence of India’s coast against expeditionary forces. These need to be imperatively included along with coastal missile batteries/ ultra long-range guns, patrol crafts, UAVs and USVs etc.

Operating Littoral Environment

The littorals comprise of different types of zones in which a Navy has to operate. These include continental shelf, surf zones, straits and archipelagos, harbours and estuaries. The main thrust of naval operations hinges upon the underwater acoustics (sonic ray plots) which do not provide an accurate measure of Sonar’s effectiveness. In the continental shelf, not much is known about the tactical usage of bioluminescence, plankton or suspended particles and other non-acoustic environmental information. Quantifiable effect on performance of different sensors and weapons under various conditions is also not available to the Commander to help him deploy them optimally. Further predictions about conditions for naval operations in continental shelf areas of interest are at best sketchy and no reliable database exists to provide correlation between various environmental conditions that may be encountered. In the surf zone region (within 10 m depth line till the beach), temporal and spatial environmental data is required for effective planning of naval operations however, there are large variations in acoustic data over short and long term. Archipelagos and straits are subject to swift changes in currents and water masses due to restricted topography, dense shipping, fishing and human traffic, which complicate planning. Most of the harbours are estuarine in nature and present a highly intricate and variable environment (tides, currents, wave amplitudes etc) warranting a holistic approach to understand the same.

Thus it can be seen that carrying out missions in littorals also involve other aspects of environment in addition to the uncertain under water acoustics which have a direct bearing on the missions. These aspects include real time and archival data bases of; meteorological surface conditions required for efficient operation of infra red, electro optical, and electromagnetic sensor and weapon systems; under water topography, accurate bathymetry, bottom composition, and detailed assessment of oceanographic water column environment for under water sensors and weapons.

The availability of overarching oceanic environmental knowledge would provide insight into enemy submarine operating/hiding areas, location of mines and underwater seaward defences. Currently the Indian Navy does not have the capability to carry out exhaustive littoral environmental scanning let alone field any sensor or weapon system that can adapt to the dynamic littoral environment and carry out missions with conviction. In fact, even for own littoral zones this type of information is not available which would enable effective deployment of static or dynamic defences.

Paradigm Shift in Approach to Littoral Defence

 

Littoral and coastal defence plans of India have undergone a sea change after 26/11; still there is a need for a paradigm shift in the way these defences are perceived as far as Indian Navy is concerned. There is strong possibility of the sea battle being fought in the littorals since the battle may not be waged at open seas. This would bring effective and capable coastal and littoral defence in to sharp focus. The days of the conventional sea fortresses and coastal gun batteries are gone; there is a need therefore to look in to strengthening, extending and backward integrating the complete range of submarine operations from the high seas to Indian littorals. This in turn would imply creating capabilities for littoral and coastal operations and acquisition of suitable class of submersibles like midget/ mini submarines and autonomous under water vehicles.  These could act as defensive force multipliers by converting the environmental disadvantages for the expeditionary forces in littorals, as potential defences against them.

 

The midget/mini submarines and the autonomous underwater vehicle are ideally placed to carry out the task of littoral defence as against the much bigger conventional or nuclear submarines. Some of the characteristics of such craft are-

-these are much smaller and therefore easier to operate in shallow waters.

-they emit much less noise and so can remain undetected.

-they have the advantage of surprise and lethality as they can detect surface ships and submarines.

-High-sustained speeds, long endurance and range are not required.

-because of their small size, they do not have to be careful about ‘squat and hump effects when operating in shallow waters.

-they can blend well with fishing craft and other coastal shipping making their detection difficult while they can search for and destroy/damage enemy vessels, the guidance can be provided from ashore or through surface craft..

-they can sit on bottom and wait for the enemy.

-they may or may not carry weapons, as they may be tasked for ISR role.

-their turnaround maintenance/ battery charging/ weapon reloading/sensor package changes etc. can be done by designated surface craft or inside harbour pens.

-One of the biggest advantages is low cost of acquisition and maintenance.

 

Doctrinally the midget/mini submarines and AUVs should be integral to littoral/coastal defence. These craft can easily be modified for carrying out additional tasks like, the security of the Indian EEZ and protection of the offshore assets.

Shallow Water Acoustics. Shallow waters pose a serious problem for under water acoustics, they remain unfriendly to current sensors like towed arrays, variable depth sonars and air dropped sono buoys due to depth limitations, deployment of torpedoes (both ship and air launched) and depth charges. Shallow waters with close proximity to land also pose difficulties for radars and magnetic anomaly detectors thus providing a relatively safe operating area for small submarines. Detection of surface craft by submarines in passive sonar mode is much easier because of their higher acoustic signatures. The surface ships would perforce resort to active sonar transmission as their passive capabilities are degraded in littorals. This in turn makes them more acoustically visible. This however, is an advantage for the operation of the submersibles in own waters.

The Unmanned Submarine (Autonomous Underwater Vehicle-AUV). An AUV is a machine that uses a propulsion system to transit through the water. It can manoeuvre in three dimensions (azimuth plane and depth), and control its speed by the use of sophisticated computerised systems onboard the vehicle itself. Autonomous underwater vehicles come under the term Unmanned underwater vehicle includes, remotely operated vehicles, paravanes, and sea gliders.

AUV can be pre programmed to adhere to course, speed and depths as desired by the operator, at a remote location and carry out specific tasks utilising a bank of sensors on the AUV. The data collection, both time and space based, is referenced with respect to coordinates of the place of operation. It can operate under most environmental conditions and because of this, they are used for accurate bathymetric survey and for sea floor mapping prior to commencing construction of subsea structures. The Navies use them for detecting enemy submarines, mines, ISR and area monitoring/ denial purposes..

            The AUVs carry out their routine tasks unattended, meaning there by that once deployed the operator is relatively free to attend to other tasks as the AUV reaches its designated area of operation and starts carrying out its mission, be it survey, search, or surveillance.

Compared with many other systems, AUVs are relatively straightforward, with fewer interoperable systems and component parts, facilitating reverse engineering of any components that might be restricted in the commercial market place. All of these factors, however also increase the likelihood that even a low tech littoral adversary could easily field offensive AUVs, this in turn leads to seeking rapid developments in AUVs by major navies.

AUVs are on the verge of three developments, which would accelerate their induction into modern navies. First is the arming of AUVs to create Unmanned Combat Undersea Vehicles (UCUVs). This is virtually accomplished with AUV designs incorporating lightweight torpedoes as weapons of choice. Heavier AUVs are being planned with missile launchers and/or heavy weight torpedoes.  However, these appear to be interim measures, since new class of weapons specific to unmanned vehicles are already under advanced development. These include much smaller and lighter missiles, torpedoes and guns firing super-cavitating ammunition.

A second potential technology development is ‘radically extended operational ranges’ for these armed AUVs. Already, the developed countries have invested in programs to create long-range underwater “sea gliders” to conduct long-range Intelligence Preparation of the Operational Environment (IPOE) missions. While the technologies enabling the “sea glider” approach probably do not provide the flexibility and propulsion power to enable armed AUVs, such programs will significantly advance the state of AUV navigation and communications technologies. Leveraging these advancements, other nascent technologies such as Air-independent-propulsion (AIP), Fuel Cell propulsion, or perhaps Aluminium/Vortex Combustors, could provide the propulsion power necessary to deploy armed AUVs even well outside of the operating area limitations of conventionally powered submarines.

Finally, “autonomy” for these armed, long range AUVs will allow them the flexibility to conduct operations far away from the homeport. Artificial intelligence (AI) based autonomous control systems are being developed at a rapid pace. Even with current state of missile/torpedo seeker technology, armed AUVs would only need enough autonomy to navigate to a known area of operations (a port, choke point, or coastal location) and launch, and the missile/torpedo would do the rest. For more complex missions, weapons could be guided by an on-site observer, for instance on a trawler or even ashore, in real-time or near real time. In short, there are a remarkably small number of “hard” technology barriers standing in the way of the long range, armed and capable AUVs.

AUVs in various configurations and roles such as communication and navigation nodes, environmental sensors in real time or ‘lie in wait’ weapon carriers are going to be the choice platform in the littorals. Networked operations of unmanned vehicles with PGMs could become the lethal weapon combo for the future. These AUVs could be expendable if required, economically viable, and offer flexibility in design, as being unmanned they can have much lesser degree of safeties.

A request for information has been floated by the Indian Navy to meet its requirement for at least 10 autonomous underwater vehicles (AUVs). These AUVs are to be developed and product ionised within four years of contract finalisation. The Navy has opted for a special category MAKE for the armed forces under the Indian Defence Procurement Procedure for high technology complex systems designed, developed and produced indigenously .Modular payload capability of the AUVs have been asked for, where in  payloads like underwater cameras for surveillance reconnaissance and high definition sonars can be mounted.

           

 

The manufacture of midget/mini submarines and AUVs in India need not be at defence shipyards as the technology and designs are commercially available. These submersibles do not require rigid safety standards of a conventional submarine as they are not required to operate at great depths, speeds or ranges, their operating range could be <100 km, their speed <10 kt, their turn around and nominal maintenance can be outsourced, their sensor packages are COTS items. Being modular in design, the weapon packages can be retrofitted. This implies that the midget/mini submarines and AUVs can be mass-produced and then sent for weapon fitment to defence shipyards.

As an illustrative example, one can take the case of the Korean VOGO, which manufactures midgets and mini submarines under various classes. Its SDV 340 is a manned submersible   which can be launched and recovered from many platforms. It is designed and built for covert and clandestine operations for depths up to 150 m.  VOGO has also manufactured the SDV 340 Recovery Vessel (SRV), which can transport, launch, and recover SDV 340 in littorals as well as at high seas. VOGO’s DV 1000 W is a hybrid submersible/surface vessel. It can transport 10 personnel at high speed to > 150 nm on the surface and proceed submerged to the target area. SDV 800 is Li-polymer battery operated submersible designed to deliver eight divers with their equipment to the target. Its long-range capability enables its use for ISR. MIDGET 200 is a small diesel electric submarine designed for covert mining, attack, ASW, covert tracking, transporting divers and ISR. It can easily operate in littorals and has various sensors like, ESM/ELINT, passive and obstacle avoidance sonars. It has two external torpedo tubes for heavy weight torpedoes.

Iran’s Ghadir is a bigger diesel/electric midget submarine, about 90 ft long and with a crew of 18 persons. It has two torpedo tubes and is said to be capable of firing tube-launched missiles also.

As far as AUVs are concerned many companies like Kongsberg Maritime (which has supplied two survey AUVs to the Indian Navy), Teledyne Gavia, Bluefin Robotics and International Submarine Engineering are already supplying AUVs. Their sizes range from man portable lightweight AUVs to 10 m long, large diameter AUVs. As an illustrative example, the Gavia AUV is a self-contained, man portable, modular survey platform capable of delivering high quality data while operating from vessels of opportunity or from the shore. The Gavia AUV can carry a variety of sensors that are especially suited for military and security applications like, Port security, Anti-submarine warfare (ASW), Mine counter measures (MCM), Surveillance, and Rapid environmental assessment (REA). As a standard, the Gavia is equipped with an optical avoidance system (OAS), GPS, and a Wireless LAN connection for data transfer. Gavia has the option of using an acoustic modem for communication, while being submerged. Additional sensors and options are available like, Side Scan Sonar, camera, swath bathymetry, high-grade inertial navigation, and obstacle avoidance. Environmental sensors such as CTD, Sound Velocity, and optical backscatter sensors are also available.  IIT Mumbai, IIT Chennai, NIOT, and DRDO are some of the Indian agencies working on the AUVs.

In conclusion it can be said that induction and embedding of midget/min submarines and AUVs  in to India’s littoral defence schemes merits serious consideration, especially since these craft can be manufactured with commercial technology indigenously and can be fielded in large numbers economically. The asymmetric advantages of defending littorals with these submersibles far outweigh the doctrinal and induction hiccups that may be encountered administratively and operationally. Therefore, there is a need for a policy level intervention to integrate these craft in the littoral defence structure including the security of the Indian EEZ and protection of the Indian Offshore assets.