High Fidelity Clutter Model for Active Sonar Navy SBIR FY2008.1 Sol No.: Navy SBIR FY2008.1 Topic No.: N08-056 Topic Title: High Fidelity Clutter Model for Active Sonar Proposal No.: N081-056-0538 Firm: Applied Physical Sciences Corp. 475 Bridge Street Suite 1 Groton, Connecticut 06340 Contact: Paul Koenigs Phone: (860) 448-3253 Web Site: www.aphysci.com Abstract: Active sonar clutter usually appears on a display as an amalgamation of point scatterers that exhibit both object and individual reflective and kinematic behavior. We propose to demonstrate the feasibility of constructing a realistic active sonar clutter model based on a few generalized concepts to synthesize most clutter types observed on Mid-Frequency active sonars. Realism is achieved by using the statistics of known clutter object attributes obtained from existing databases. The clutter model uses superellipsoids to define basic building blocks. Each type of clutter block is populated with discrete point scatters. The population, density, scattering coefficient, velocity, and fading characteristics of the scatterers are described using the appropriate statistics. The acoustic propagation response function for each scatterer is obtained using a high fidelity acoustic model. A realistic time series of a clutter object echo is obtained by convolving the transmit waveform with the system, propagation and clutter object response functions. Because all the functions, save one, are represented as delta functions, this is not computationally intensive. The model includes the effects of own ship motion, the specific sonar design, waveforms, and acoustic propagation including attenuation and multipath arrivals. The clutter exhibits deterministic and stochastically dependent, spatial, temporal, and intensity characteristics. Benefits: Well qualified and experienced active sonar operators are needed to effectively prosecute quiet threats. To acquire and maintain their proficiency, operators need routine realistic training or real life exercises because ASW is a difficult and perishable skill. At-sea experience is difficult to obtain because of time, money and operational restrictions. Training with simulators can be a viable option to at-sea experience if it is realistic. The current on-board active sonar trainer does not contain realistic clutter that can typically distract an operator and consume valuable search time when a target is present. The mark of a skilled operator is the ability to detect and classify a real target on cluttered displays. Thus, without routine at-sea experience, a key component in training new personnel and maintaining the skills of an experienced operator is a realistic clutter model component in the trainer. Our current focus is to commercialize the modeling concept and approach for the AN/SQQ89 AV15 On Board Trainer. The next most likely prospect for commercialization is the Fleet Antisubmarine Warfare Command (FASWC). This command brings together the air, submarine and surface components of ASW to provide standardized ASW training for the entire Navy. We would also investigate the utility of this approach for in fleet level training tools that need of more realistic clutter models. Fleet training enhancements would be pursued through the Chief of Naval Education and Training (CNET). This could significantly enhance the training capabilities of all Navy ships, squadrons and task forces warfare systems, not just ASW. There are several additional avenues available for commercialization. If the basic concept is successful it would demonstrate that computationally intensive modeling of complex scattering objects and propagation can be circumvented and high fidelity clutter can be inserted at suitable places in many complex systems. Radar is a prime example, but trainers and simulators for commercial cars, buses, ships and aircraft also require realistic environments. Video gaming is another prospect. The introduction of easily generated high fidelity clutter could elevate many of the existing commercial games and professional training products to new levels. Return