Obstacle avoidance sonar for submarines

The Advanced Mine Detection Sonar (AMDS) system was designed to operate in poor environments with high biological and/or shallow-water boundary conditions. It provides increased capability for active detection of volume, close-tethered, and bottom mines, as well as submarine and surface target active/passive detection for ASW and collision avoidance. It also provides bottom topography mapping capability for precise submarine navigation in uncharted littoral waters. It accomplishes this by using advanced processing techniques with extremely narrow beamwidths. The receive array consists of 36 modules arranged in a 15-ft-diameter semicircle at the bottom of the submarine sonar dome to form a chin-mounted array. Each module consists of 40 piezoelectric rubber elements. The modules provide the necessary signal conditioning to the element data prior to signal transmission (uplink) through the hull. The elements are amplified, filtered, converted to digital signals by an A/D converter, and multiplexed prior to uplink to the inboard receiver. Each module also has a downlink over which it receives synchronization and mode/gain control. Uplink and downlink transmission is done using fiberoptic telemetry. AMDS was installed on the USS Asheville. The high-frequency chin array for Virginia class submarines is based on the Asheville design.