Shallow Water Synthetic Aperture Sonar

Acoustical MCM and ASW operations in shallow water are plagued by the prevalence of false targets as well as strong reverberation and multipath. The combination of imaging and environmental adaptivity may be the key to overcoming these problems. Synthetic aperture sonar (SAS) is a revolutionary technology which provides at least an order of magnitude search rate improvement over side looking sonar (SLS) while maintaining the same resolution. Important classification and identification cues are obtained at search ranges by imaging the target's highlight structures and acoustic shadow. These cues will reduce false alarm rate (FAR) in MCM and may present the only viable means by which to discriminate low or no-doppler targets against clutter in ASW. Extending SAS capabilities into shallow water requires modifying the SAS processor to account for propagation effects. Dynamics Technology, Inc. (DTI) proposes several alternatives for incorporating model-based matched filtering (MBMF) into the existing SAS processing stream to counter multipath distortions of the signal waveform. We will also evaluate the effectiveness of ely tracking environmental variations in the SAS imaging context. Emulated and recently collected field data will provide the test bed for these concepts.