Exploitation of Non-Traditional Scattering (NTS)
Objective of Phase I Effort
The objective of this research is to identify target scattering phenomena that can add value to air ASW systems. Specifically, we seek to: estimate improvements applicable to air ASW systems; define system concepts that can capitalize on new scattering phenomena, and identify the signal processing steps involved. For the Phase I option effort, the objective is to develop buoy stabilization algorithms that can provide improved target, source and receiver location estimates based on acoustic information.
Summary of Results from the Phase I Effort
New signal processing techniques have been developed for exploiting non-traditional target scattering in air ASW systems. The techniques have been tested using at-sea data sets. The performance of the new target system as a function of scattering angle, pulse length, adaptive noise reduction processing and integration times have been measured. High-resolution time-frequency analysis methods were used to extract new echo classification features. Significant improvements in detection rates are shown using adaptive noise reduction technology. Results indicate that certain multistatic phenomena, predicted by scattering theory are present in incoherent acoustic source echoes. A new target detection methodology, based on change detection techniques, has been developed for reverberation limited environments. These results suggest that air ASW systems can achieve improved search rates by utilizing new signal processing techniques and new multistatic search geometries. As part of the Phase I option, new sonobuoy stabilization algorithms have been developed that reduce the sensor location uncertainty of air ASW source and receiver geometry by 75%. The techniques utilize acoustic arrival information to determine array geometry as a function of time. The stabilization algorithms lead to improved change detection performance, as well as more accurate direct blast arrival time predictions and target echo angle measurements. An end-to-end processing software system termed Multistatic Air ASW Awareness (M3A) has been developed as part of the Phase I research. This software has been installed at the Naval Air Warfare Center to aid other scientists and engineers in studying these new scattering phenomena and associated signal processing techniques.
Potential Applications and Benefits
The potential application of this research include numerous Navy ASW sonar systems that utilize bistatic or mutlistatic geometries. Specific systems that can benefit from this research include air ASW Systems such as IEER and AEER as well as MACE, Distant Thunder, LELFAS and submarine bistatic processing efforts. The technology developed under this SBIR can improve ASW search rates for multistatic systems by increasing signal to noise ratios without new sensors and providing wider area coverage with the same number of sensors.
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