FOREIGN ASW TECHNOLOGY DEVELOPMENTS

The most dramatic examples of rest-of-the-world countries acquiring advanced undersea technology are occurring in the Asian-Pacific region. Many of the Pacific Rim nations currently possess booming economies and associated rising defense expenditures, in contrast to most of the world. Much of the military emphasis is related to acquiring advanced naval and undersea warfare capabilities; in fact, it is believed that 40-60 percent of the naval export market in the coming decades will be from these Asian countries. Acquisition of advanced submarines is also receiving priority. China, India, North Korea, and Japan already have large submarine inventories, and South Korea and Taiwan are in the process of acquiring large submarine fleets (a dozen or more). Smaller submarine orders-of-battle can be found in Australia, Indonesia, and Pakistan and will eventually be acquired by Malaysia, Singapore, and Thailand. All of this submarine activity is causing these same Asian nations to reassess and upgrade their overall ASW capabilities, creating an opportunity for both Russian and Western suppliers to sell their advanced ASW equipment.

The cause for worry by the U.S. Navy is evident from even a cursory review of various exercises which suggests that the U.S. Navy {including our Submarine Force) is not bullet-proof. It is important to make our Navy as bullet-proof as we can afford, because incidents, which from a military perspective might seem small, can have big policy implications. This has been illustrated by a fire-fight in Somalia, a single mortar round in a Sarajevo marketplace, and a terrorist attack on a Marine Barracks in Lebanon. What impact would a single ship sinking with high combat deaths have on U.S. policy? It would be better not to find out.

Mines

Some of the most advanced bottom mines in the world are being acquired by rest-of-the-world countries. Russia alone is offering customers a half-dozen or more varieties, typically with warheads equivalent to 1500-3000 pounds of TNT. British, French, Italian, and Swedish suppliers are also exporting large-warhead, advanced bottom mines to their clients. In addition, Russia is selling ASW-capable mines such as the PMK-1 and MSHM types that feature rocket-propelled projectiles and war-heads. Even China is exporting a rocket-propelled (vertically) rising mine designated EM-52. Iran is reportedly acquiring a variety of bottom and moored mines (including rocket-propelled) to potentially control access to the Persian Gulf by both shipping and naval forces.

As an example of the advanced mine technology that is being transferred, it is interesting to note that microprocessor-controlled target detection devices (TDDs) are included in advanced bottom mines being supplied by the West. These can be programmed for sophisticated signature matching. Can Russia be far behind in this area? What target types would mines deployed at the approaches to the Chah Bahar submarine base be programmed against in a future contingency? A final disturbing note is that advanced TDDs are available in retrofit packages (including at least one Third World supplier today} to modernize older mines for a fraction of the cost of a new mine.

Submarine Systems (Sensors. Torpedoes)

The recent sale of Agosta 90B submarines from France to Pakistan provides a good illustration of where diesel submarine hull, propulsion, and combat system related technologies are heading. The Agosta 90B features advanced silencing, high strength steel hull construction, and reportedly an air independent propulsion (AIP} system. If the latter occurs, it could represent the first export sale of modern AIP technology to any country. This submarine will also include the new French combat system that is also going on their own Amethyst class submarines. With these submarines, Pakistan is also expected to get SM-39 sub-merged launch Exocet cruise missiles (first such sale to the Third World} and F17 Mod 2 heavyweight torpedoes with combined acoustic and wake homing capabilities.

The advanced combat systems on modern diesel submarines are very impressive. Atlas Elektronik of Germany and Thomson Sintra of France are two of the leading exporters. Their systems are fully integrated and feature advanced signal processing, data fusion, and information management techniques to support automatic tracking and fire control, e.g., that allow the firing and wire guidance of torpedoes simultaneously. These combat systems, which also have surface ship counterparts, can integrate the contact information from a variety of acoustic and non-acoustic sensors. In the future flank arrays, towed arrays, and nonpenetrating optronic masts will be standard capabilities on export diesel submarines. It is not hard to also imagine user-friendly work-stations in submarine combat spaces that are no harder to operate than a complex video arcade game. In the far future, even in-situ wake detection sensors (e.g., on submarine sails) are possible for rest-of-the-world submarines, perhaps similar to those technologies that Russia reportedly has been pursuing.

Shifting to the business end of the submarine, the major ASW-capable heavyweight torpedo suppliers in the world today are the U.S. (NT-37, Mic 48), the U.K. (figerfish, Spearfish in the future), France (L-517, F-17 series), Germany (SUT, Seehecht, Seahake in the future), Italy (Al84), Sweden (TP-62ffype 2000 in the future), and Russia (fest-96, Test-71ME).

Two of the most advanced Western torpedoes under development are the German Seahake Mod 1 (DM2A4) and the Swedish TP-62 (Export Torpedo 2000). The Seahalce design is compatible with the early German torpedoes and allows use of upgrade kits to convert SUT/SST-4/Seehecht torpedoes (in numerous rest-of-the-world inventories) to the more advanced Seahake model. This allows an affordable means of acquiring state-of-the-art acoustic homing, wire guidance, and quiet operation capabilities in heavy-weight torpedoes. The Swedish TP-62, which has been certified for bottom launch, also features significant counter-countermeasures (CCM) capability and low radiated noise plus high maneuverability (reportedly about 45 degrees per second).

Undersea Surveillance System Developments

Two ASW technology areas that bear watching in the future are related to fielding undersea surveillance systems. The first is acoustic and/or non-acoustic bottom surveillance sensors, i.e., employed on the seabed in harbor approaches, straits, or other littoral choke points. Russia and the U.S. have pursued this technology, e.g., the current U.S. Advanced Deployable Surveillance program. Other Western suppliers are also developing similar systems, but only on a smaller scale. The Canadian firm C-Tech Ltd. offers for export a seabed active sonar-based harbor surveillance system (CSAS-80) for detection of midget submarines or swimmer delivery vehicles. On a larger scale, the Italian WELSE consortium has been involved in the development of an advanced seabed-based ASW area system (ASW AS) capable of use in 150 meter water depths. ASW AS is fitted with both acoustic (active/passive) and non-acoustic (e.g., magnetic) sensors. In the future, seabed surveillance technology could shift to covert E-field and DC magnetometer sensors.

The second undersea surveillance technology area that needs to be monitored is low frequency active acoustics (LFAA). In addition to tactical LF AA possibilities for ASW aircraft (dipping sonars, sonobuoys) and warships (hull and variable depth sonars, towed receivers), both fixed and large mobile surveillance-related LFAA technologies are also being pursued by Russia, the U.S., and a few other countries. This represents a long-term concern in terms of proliferation of LFAA surveillance systems in the rest-of-the-world.

Inhibiting the transfer of this LFAA surveillance technology is the complexity of integrating key components (projectors, receivers, signal processors, communications) into a viable overall system. Many countries are developing LFAA projectors and high gain acoustic receive arrays for various applications. However, combing projectors and receivers with the required signal processing and communications (particularly for bi-static/multi-static concepts) remains the key challenge to LFAA system designers.

Coastal or Sbipboard Radar and ESM (SIGINT) Systems

Why should coastal (or shipboard) radars or electronic support measure (ESM) systems capable of signals intelligence (SIGINT) be of concern to U.S. attack submarines? It is because U.S. SSNs are spending much more time at periscope depth with masts/antennas exposed in order to facilitate communications with other naval units participating in joint task force operations in places like the Adriatic Sea off Bosnia. In recognition of this trend for SSNs to be more integral members of joint or combined coalition operations, ARP A and others are investigating stealth sail concepts for future submarines. Just as important in this regard is the tracking of commercial and military coastal surveillance technology developments (e.g.. by Marconi Radar Systems of Italy), so that the susceptibility of an exposed mast or sail to adversary counter-detection is well understood. In addition to horizon-limited systems (capable of 20-40 nmi detections against small surface targets depending on coastal terrain and elevation), Marconi and others are continuing to develop advanced over-the-horizon, high frequency radars with even greater detection range potential. In the future, coastal surveillance radar technologies could evolve away from monostatic systems making hard body detections to bi-static systems (e.g., using unmanned air vehicles as receive platforms) that are capable of detecting surface walces or other effects under certain conditions.

Similarly, a comparison of current submarine communication frequencies (ship-to-shore, ship-to-ship, ship-to-aircraft) with the frequency coverage of current surveillance receivers, communications intelligence equipment, and electronic intelligence equipment suggests a significant amount of overlap. Thus, the ability to detect and localize SSN communications also needs to be assessed.

Aircraft Systems (Sensors. Torpedoes)

There are over 1800 ASW-capable aircraft in the world with slightly over half being helicopters (equally divided between large and small helo variants). If the U.S., the former Soviet Union, and China are excluded, that still leaves about 850 ASW-capable aircraft, with about two-thirds being helicopters (and over half of the helicopters being of the small variety). The U.S., Europe, and Russia offer medium weight (9-14 tons) or large helicopters. The main Russian export version is the KA-28 aircraft with dipping sonar, sonobuoys, lightweight torpedoes, and other underwater ordnance (rockets, bombs). The same helicopter suppliers (U.S., Europe, Russia) also offer lightweight (5-7 tons) or small ASW-capable models that have reduced payload and vehicle endurance.

Shifting from ASW helicopters to ASW-capable (or potentially ASW-capable) maritime patrol aircraft (MPA), we see that they also come in two flavors, i.e., long range MPA (10-12 hours endurance) and medium range MPA (6-8 hours endurance). Although more rare in Third World militaries than helicopters, remember that it was an Argentine fixed wing aircraft that harassed the HMS CONQUEROR after it sank the BELGRANO. India has the highly ASW-capable Russian Bear F MPA, and other countries, including South Korea, have the U.S. P-3C. Medium range MPA are more plentiful than long range MPA, and most can be configured for either ASW or ASUW missions (not always easily reconfigurable), depending on the interest of the particular country.

Peeling the onion a little further, many ASW helicopters are equipped with dipping (or dunking) sonars. These systems have, in various past ASW exercises, proven to be a nemesis for submarines, often working well in littoral environments and being difficult for a submarine to disengage from once the helicopter gains contact. Both ASW helicopters and fixed wing aircraft employ acoustic sonobuoys of the LOFAR/JEZEBEL, DIFAR, and CASS/DICASS generic types. These dipping sonars, active/passive sonobuoys, and associated advances signal processors are widely exported by several nations with the U.S., the U.K., France, and Russia being the biggest suppliers. In the future, user-friendly bi-static systems (e.g., with impulsive sources) could be widely exported by Russia and/or the West.

Shifting from acoustic sensors to non-acoustic sensors, a survey of standard equipment on most current ASW-capable aircraft indicates that the following four technologies are prevalent: high resolution surface search radars including inverse synthetic aperture radar types (with varying capabilities to detect submarine masts and periscopes), forward looking infrared, ESM, and magnetic anomaly detection. In the future, we can expect to see advanced magnetic systems (e.g., extreme low frequency electro-magnetic), light detection and ranging systems, and other electro-optical systems (e.g., bioiluminescence).

One of these future aircraft-based non-acoustic technologies, LIDAR, can be illustrated by two systems, one commercial and one military. The Hawk Eye LID AR system is a joint Swedish/Canadian commercial effort. This helicopter pod-mounted system conducts surveys at nearly 1000 feet altitude and is capable of detections 20-35 meters beneath the sea surface (2.5 attenuation lengths), depending on the associated optical clarity of the waters. The Amethyst blue-green laser is a military system employed on Russian Bear F Mod 4 MPA. The aircraft flies at 328 feet (100 meters) altitude and 200 knots airspeed and is capable of searching a 100 meter wide swath for targets in a portion of the first 100 feet of the water column (how large a portion depends on specific conditions).

The ASW-capable aircraft survey would not be complete without a review of air deployed ASW ordnance. Although aerial bombs (50-200 kg) and depth charges are available, including some advanced models that feature active homing (e.g., Saab Missile’s intelligent depth charge), lightweight ASW torpedoes remain the weapon of choice against large submarines under most situations. The primary lightweight torpedo suppliers in the world today are the U.S. (Mk 46, Mk 50 in the future), the U .K. (Stingray), Italy (A244, MU-90 in the future), France (MU-90 in the future), Sweden (fP 43XO), TP 43X2), and Russia (APSET-95, APR-2E). The Italian A244 series has been provided to about 15 countries and has demonstrated performance in shallow water conditions (e.g., 150-200 feet of water). The Italian A290 and French Murene programs have been combined in the joint MU-90/Impact torpedo development effort. All three programs have advanced counter-countermeasure features and are capable of being air dropped in water at least as shallow as 100 feet. It should be noted that, in the future, some of these lightweight torpedoes could become the payloads for advanced ASW standoff weapons (typically 5 to 30 nmi range). Several countries have developed or are currently developing surface-launched ASW torpedo missile systems; these include the U.S. (ASROC, Vertical Launch AS-ROC), France/Italy (Milas), Russia (Silex, Medvedka), and China (CY-1).

Surface Ship Active Sonors

ASW-capable surface ship developments parallel many of those already discussed for submarines and aircraft, e.g., passive sonars and combat systems similar to those for submarines, and light-weight torpedoes similar (if not virtually the same) as those for ASW aircraft. The main way that surface ship ASW developments are truly unique is in the area of active sonars, particularly systems being designed for use by surface vessels prevalent in many rest-of-the-world navies. Three examples being developed by Thomson Sintra and other are: 1) the very low frequency (about 1 KHz SLASM system for frigates/destroyers that combines a variable depth sonar towfish and activated passive receive arrays clipped onto the same towfish; 2) the active toward array sonar (AT AS) system suitable for small ships ( > 250 tons) that combines flextensional transducer source technology to activate a towed linear receive array (in an approximate 3 KHz monostatic configuration); and 3) the Gudgeon compact ASW sonar designed for shallow water use (in hull-mounted and/or VDS configurations at about 13 KHz). It should be noted that Taiwan, Oman and Pakistan have reportedly already placed orders for the ATAS system.