Acoustics research at ARL:UT was initiated in 1949 to study high resolution sonar for mine hunting applications. The high resolution sonar program continues today. The program has a distinguished history of accomplishment, and has figured prominently in the development of much of the U.S. Navy’s current capability in this crucial area. Areas of investigation include acoustic propagation, ambient noise, reverberation, scattering,target physics,signal processing, imaging, and computer-aided detection. A variety of prototype sonars have been built and delivered to the U.S. Navy for use aboard surface ships, submarines, autonomous underwater vehicles, and to provide security at various U.S. Navy piers and other installations. Applications include mine detection and avoidance, obstacle avoidance, underwater mapping, navigation, diver hand-held sonars, and swimmer detection.
Beginning in 1963, ARL:UT’s acoustics program was expanded from its roots in high-frequency, high-resolution sonars to include tactical frequency sonars for use in antisubmarine warfare (ASW). This work involved pioneering efforts in the development of computer algorithms for classification of target echoes to distinguish submarine echoes from the variety of clutter present in a typical active sonar display. Drawing upon technical strengths in sensor signal and information processing, with a strong emphasis on innovative techniques for detecting, classifying, tracking, and localizing contacts of interest, ARL:UT has developed the U.S. Navy’s primary capability for echo tracking and classification.
For some 30 years, ARL:UT has conducted research to reduce the vulnerability of submarines to threat sensor counter-detection by reducing both radiated noise levels and acoustic target strength. This work includes development, construction, and operation of the Target Strength Measurement System (TSMS) to conduct full-scale measurements of submarine target strength in the open ocean; development of sophisticated techniques to analyze and interpret acoustic target strength data; and development of analytic submarine target strength models, primarily in the validation process.
In 1972, ARL:UT again broadened its acoustics programs to include low frequency passive sonar used in undersea surveillance systems for detection and tracking of submarines. ARL:UT research in this program has led to fundamental advances in our understanding of underwater acoustic propagation and our capability to model propagation in complex ocean environments. It has also produced improved understanding of ocean acoustic noise processes, including both spatial and temporal characteristics. An essential aspect of this work has been the development of advanced signal processing techniques, including adaptive methods for dealing with the noise environment and extracting low level signals. The low frequency acoustics program has resulted in signficant contributions to the U.S. Navy’s undersea surveillance capability, and has also figured prominently in improving the passive sonars used aboard U.S. Navy submarines to detect and track enemy submarines.
In addition to its sonar programs, ARL:UT has an active industrial acoustics program, which is engaged in a variety of projects oriented primarily toward the use of high-power, nonlinear acoustics for environmental cleanup and medical ultrasonic applications. Results achieved include:
- Reduction of pollution in coal-fired power plant exhaust streams
- Improved combustion efficiency in coal-fired power plants
- Medical ultrasonic remote delivery for treatment of gall stones
Recent work includes development of an acoustic agglomerator to reduce particulate emissions. ARL:UT scientists and engineers are also investigating the development of new applications in thermoacoustics.
ARL:UT has been involved in electromagnetics research since 1945, starting with involvement in early radar systems. Since that time the work has evolved to focus on electromagnetic propagation effects and their impact on satellite systems. Recently, the focus has been on several aspects related to the Global Positioning System (GPS), namely: global monitoring of the signal in order to improve ephemeris and provide better global coverage, long baseline differential positioning, and ionospheric measurement and specification.
ARL:UT’s involvement in space-based geopositioning predates the GPS constellation with our participation in the U.S. Navy TRANSIT program. This included ARL:UT staff participation in the National Science Foundation’s McMurdo, Antarctica, research stations over many years. This early work with TRANSIT led to a natural evolution of involvement with the GPS system. When GPS replaced TRANSIT, the Navy directed ARL:UT to decommission the navigation satellites and convert them to a new function as the Navy’s Ionospheric Monitoring System (NIMS).
ARL:UT has long been interested in the impact of the ionosphere on signals passing through it. ARL:UT was instrumental in the development of computerized ionospheric tomography (CIT) to specify the electron density of the ionosphere by utilizing the data collected from the NIMS and GPS satellites. ARL:UT has continued to push the envelope on the specification of the ionosphere by creating the first ionospheric data assimilative model capable of ingesting a large number of data types. With this capability it is possible to not only specify the electron density but also the conductivity of the ionosphere.
As part of the overall electromagnetics research program ARL:UT also conducts research in unique antenna designs. These unique designs include electrically very small HF antennas (approaching 0.01 l) and very wide band antennas for ultra-wideband (UWB) usage. The very small HF antennas have a variety of potential uses due to the compact design and high efficiency. The UWB antenna is designed in such a way as to maximize the transmission efficiency and minimize the ringing induced by very narrow pulses.
ARL:UT’s initial entry into the information technology arena was oriented toward developing systems to collect and analyze large volumes of data;generated by the U.S. Army during the testing of field artillery Command and Control (C2) systems. This led to work developing instrumentation and software for non-intrusive collection and distribution of digital Command Control, Communication, Computers, and Intelligence (C4I) data for live training systems at the U.S. Army's maneuver combat training centers (MCTCs). Most recently, we have focused on the integration of information between the operational C4I community and the modeling and simulation activities that support the employment, training, and testing of C4I systems.
In addition, our information systems engineers, analysts, and developers have implemented technologies required for data warehousing, data mining, Web-based information retrieval and dissemination, technology migration re-engineering, live training simulation, and embedded real-time simulation. Sponsors continue to look to ARL:UT for strong capabilities in system requirements elicitation, analysis, and management; software requirements and design methodologies and notations; data base design, implementation and administration; client-server and Web-based systems and tools (including development languages and environments); and network and operating systems configuration and administration.
ARL:UT has expanded substantially from its initial research in the information sciences arena, and today supports a variety of modeling and simulation programs for all the services as well as for joint-level and DoD-level efforts. These efforts—which include C4I and simulation integration, modeling and simulation for defense acquisition, simulation interoperability standards, and formalized knowledge specifications—have allowed ARL:UT to significantly expand its expertise in the engineering and management of data, knowledge, and software.
In the 1990s, recognizing the need for cyber security, ARL:UT initiated research and development in computer network security, intrusion detection, and cyber information assurance. This research led to development of working prototypes that now actively support DoD, the associated intelligence community, and other government agencies. Working closely with these various government groups to better understand their requirements, ARLUT continues to research and design enhancements to each customized prototype, drawing on technical strengths in the areas of computer network security, rule-based expert systems, database technology, knowledge engineering, data mining, and machine learning. Current work focuses on real-time network intrusion monitoring, off-line intrusion analysis, computer network modeling and simulation, probabilistic modeling of attack sequences, critical information protection / insider threat mitigation, and insider threat detection using data fusion.