A High-Resolution Active Sonar System For Detecting Mines In Very Shallow Water From An Amphibious Vehicle

A Forward-looking synthetic aperture sonar is proposed for detecting mines ahead of an amphibious vehicle in the very shallow water/surf zone. The sonar provides unique high resolution range-elevation images for detecting and locating moored, bottom resting, and buried mines. Fine elevation resolution, obtained synthetically, defines the water/bottom boundary and hence provides a strong discriminant against buried objects. Underwater mines are resolved into several pixels in range and elevation for ease of detection. The system will also have a useful azimuthal resolution to enable avoiding mines and other obstacles. The system produces the images at normal vehicle speeds. High resolution and high speed are both possible due to an innovative multi-beam bistatic configuration. High quality synthetic aperture imaging is possible in the presence of severe motion irregularities because of a reliable, high accuracy, computationally efficient autofocus technique developed by GORCA. Recently, GORCA collected and successfully imaged initial experimental synthetic aperture shallow water data, in the presence of severe motion irregularities, using an internally developed single-beam high resolution sonar. In Phase I, the existing system will be used to collect and process data containing representative test targets, and a multi-beam prototype will be designed.