May 18, 2016

Undersea warfare gamechangers - China building upgraded SOSUS and US upgrading sensor and fielding network of undersea robots

The China State Shipbuilding Corporation (CSSC) has proposed the construction of a network of ship and subsurface sensors that could significantly erode the undersea warfare advantage held by US and Russian submarines and contribute greatly to future Chinese ability to control the South China Sea (SCS).

Details of the network of sensors, called the 'Underwater Great Wall Project', were revealed in a CSSC booth at a public exhibition in China in late 2015.

While some elements of this network have been known for some time, CSSC is now in effect proposing an improved Chinese version of the Sound Surveillance System (SOSUS) that for a time gave the US a significant advantage in countering Soviet submarines during the Cold War. The system proposed by CSSC is likely being obtained by China's People's Liberation Army Navy (PLAN) but may also be offered for export.

SOSUS, an acronym for sound surveillance system, is a chain of underwater listening posts located around the world in places such as the Atlantic Ocean near Greenland, Iceland and the United Kingdom—the GIUK gap—and at various locations in the Pacific Ocean. The United States Navy's initial intent for the system was for tracking Soviet submarines, which had to pass through the gap to attack targets further west. It was later supplemented by mobile assets such as the Surveillance Towed Array Sensor System (SURTASS), and became part of the Integrated Undersea Surveillance System (IUSS).

SOSUS consists of high-gain long fixed arrays in the deep ocean basins

BEAM accesses form beams from multiple hydrophone arrays trained on the seafloor to provide signal gain obtained through beam forming.

PHONE accesses individual hydrophones from arrays throughout the oceans provides omni-directional coverage.


CSSC says that, among other things, its objective is to provide customers with "a package solution in terms of underwater environment monitoring and collection, real-time location, tracing of surface and underwater targets, warning of seaquakes, tsunamis, and other disasters as well as marine scientific research".

The corporation says in the document that its "R and D and production bases in Beijing and Wuxi [have] the ability to support the whole industry chain covering fundamental research, key technology development, solution design, overall system integration, core equipment development, production, and operation service support".

The shipbuilding conglomerate says it has 10 series of products on offer that include systems relating to marine observation, oceanographic instrumentation, underwater robotics, and ship support.

Specific components of CSSC's surveillance system include surface ships, sonar systems, underwater security equipment, marine oil and gas exploration equipment, underwater unmanned equipment, and marine instrument electronic equipment.

US Anti-submarine Warfare

From a Statemeent before the house armed services seapower and projection subcommittee on “Game Changers - Undersea Warfare"
October 27,2015 Bryan Clark, Senior Fellow, Center for Strategic and Budgetary Assessments

When the Soviet Navy began fielding nuclear submarines, the American Navy exploited its “first mover” advantage in passive sonar to establish the passive Sound Surveillance System (SOSUS) network off the U.S. coast and at key chokepoints between the Soviet Union and the open ocean.

The combination of passive sonar Anti submarine Warfare (ASW) systems and its own sound-silencing efforts gave the U.S. Navy a significant advantage over relatively noisy Soviet submarines. This overmatch, however, slowly began to erode in the mid-1970s after the Soviet Union learned of their submarines’ acoustic vulnerability from the John Walker-led spy ring and obtained technology for submarine quieting from a variety of sources. Newer Soviet submarines such as the Akula and Sierra classes were much quieter than their predecessors, but were only fielded in small numbers before the Soviet economy began to falter, leading to delayed construction and inadequate sustainment.

Efforts to protect submarines from being detected since the Cold War have emphasized quieting, since passive sonar is the predominant sensor used for ASW. But today a growing number of new ASW systems do not listen for a submarine’s radiated noise. For example, low-frequency active sonar is now widely used by European and Asian navies in variable depth sonar (VDS) systems and will be part of the U.S. Littoral Combat Ship (LCS) ASW mission package. Non-acoustic ASW technologies that detect chemical or radiological emissions or bounce laser light off a submarine are becoming more operationally useful due to improved computer processing and modeling of the undersea environment.

These active sonar and non-acoustic capabilities are likely to be best exploited by mobile platforms such as unmanned vehicles, aircraft, and ships because they are smaller than passive sonar systems. In contrast, to achieve long detection ranges passive sonars must be physically large so they can hear faint noise at the lower frequencies that suffer less attenuation. This makes fixed systems on the sea floor like SOSUS or towed systems such as SURTASS better able to exploit passive sonar improvements.



The same advancements that are improving ASW capabilities will also enable a new generation of sophisticated counter-detection technologies and techniques. For example, against passive sonar a submarine or unmanned undersea vehicle (UUV) could emit sound to reduce its radiated noise using a technique similar to that of noise cancelling headphones. Against active sonars, undersea platforms could—by themselves or in concert with UUVs and other stationary or floating systems—conduct acoustic jamming or decoy
operations similar to those done by electronic warfare systems against radar.

New power and control technologies are improving the endurance and reliability of UUVs, which will likely be able to operate unrefueled for months within the next decade. The autonomy of UUVs will remain constrained, however, by imperfect situational awareness. For example, while a UUV may have the computer algorithms and control systems to avoid safety hazards or security threats, it may not be able to understand with certainty where hazards and threats are and what they are doing. In the face of uncertain data, a human operator can make choices and be accountable for the results

The U.S. surface naval force employs state-of-the-art ASW technology aboard numerous Arleigh Burke-class destroyers. The SQQ-89A(V)15 Combat System, which will be aboard 64 destroyers by 2020, and the new MFTA (multi-function towed arrays) are game-changers in ASW operations. The combined capabilities alter how the surface Navy searches and tracks submarines. With enhanced sensor capability and data processing, the surface naval forces have an increased role in integrated ASW operations.


ASW surface ships can remain longer on station in comparison to aircraft and provide real-time command and control capability beyond that of a submarine," he wrote. "In stride with the surface Navy's technological advancements, the aviation community has new platforms to meet the ASW mission. The MH-60R Sea Hawk helicopter and P-8A Poseidon aircraft are to be fully integrated in the fleet by 2020 [and] are already providing an improved ASW capability in fleet operations... The rotary aircraft has an enhanced active dipping sonar to increase detection ranges from three to seven times compared to legacy systems.

"The P-8A adds an improved sensor search capability by utilizing a multi-static active coherent (MAC) system, which comprises sonobuoys (source and receiver) and advanced processing. In addition to the new platforms and technological advancements, all ASW ships and aircraft in the future will employ the Mk 54 lightweight torpedo, which integrates several years of weapons technology. By 2020, these new improvements collectively in the surface and aviation communities will create a powerful ASW capability. The Navy must further improve requisite training to meet the new capabilities and foster a fleetwide culture that prioritizes the ASW mission."

Meanwhile, the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., has been pursuing two ASW programs: Distributed Agile Submarine Hunting (DASH) and ASW Continuous Trail Unmanned Vessel (ACTUV). DASH was designed to reverse the asymmetric advantage of the threat from quiet new submarines through the development of advanced standoff sensing from unmanned systems.



Future undersea competition

Some operational features of this competition are:
• A new predominant sensing technology. The effectiveness of traditional passive sonar will decline as submarines become quieter, their stealth is enhanced with countermeasures, and rivals deploy more unmanned systems that radiate little noise. While ASW relied primarily on passive sonar for the last 50 years, the dominant detection method by the 2020s may be lowfrequency active sonar, non-acoustic detection, or some other previously unexploited technique made possible by ongoing technological advances.
• Undersea families of systems. Submarines will increasingly need to shift from being front-line tactical platforms like aircraft to being host and coordination platforms like aircraft carriers. Large UUVs and other deployed systems that are smaller and less detectable could increasingly be used instead of manned submarines for tactical missions close to enemy shores including coastal intelligence gathering, surveillance, mining, or electronic warfare.
• Undersea “battle networks.” New longer-range sensors and emerging undersea communication capabilities will enable undersea fire control network operations analogous to those that use radio signals above the surface of the water. Undersea networks could also enable coordinated surveillance or attack operations by swarms of UUVs operating autonomously or controlled from a manned submarine or other platform.
• Seabed warfare: U.S. forces will need more immediately available undersea capacity inside areas contested by adversary surface and air A2/AD networks.

Deployed and fixed sensors, payload modules, and UUVs supported by systems like FDECO could augment U.S. submarine capacity and be managed by them during a conflict. Increased reliance on these capabilities will create a competition in the ability to place or eliminate systems on the coastal seabed, including capabilities for rapidly surveying and assessing the sea floor.

SOURCES - IHS Janes, military aerospace, Statemeent before the house armed services seapower and projection subcommittee on “Game Changers - Undersea Warfare" October 27,2015 Bryan Clark, Senior Fellow, Center for Strategic and Budgetary Assessments, global Security, Wikipedia

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