Abstract: An expendable moving echo radiator suitable for providing a decoy to attr a homing torpedo and divert the torpedo away from its intended target is disclosed. The present invention provides an expandable and collapsible curtain for deployment from a capsule launched from a submarine or other sea vessel. In its expanded configuration, the curtain is characterized by a physical profile sufficient to reflect acoustic waves and to generate echoes substantially similar to echo signals generated by an actual, full size submarine or other target. The present invention is further provided with propulsion means, as well as means for enhancing its capability to capture a torpedo's sensors. It can also be provided with explosives to destroy lured torpedoes. The expendable device can be used to simulate a submarine for anti-submarine warfare (ASW) training, thereby affording the advantage that a package of easily transportable size becomes a full size submarine-like target.

Abstract: Acoustically mapping (fingerprinting) the main channel, or `Q` routes, of a arbor, over relatively long time periods by using transducers anchored near the harbor or Q route floor. Sonar pulse returns are processed so that echoes from acoustic targets are constantly monitored and integrated over long periods of time. The integrated sonar data are used to establish a characteristic bottom-image map for the presence and location of permanent objects such as debris, underwater formations and the like. The long term, integrated record is obtained to establish a reliable acoustic fingerprint or reference mapping of the bottom. This acoustical record or map, which is quite stable over long periods of time, is used to compare newly detected acoustic variances from the established map. A combination of active and passive acoustic sensors that are installed at fixed positions submerged in the channel permit the determination of both range and bearing when an intruding object has been detected.

Abstract: A sonobuoy having a directional hydrophone centrally enclosed in a flexib acoustically transparent, spherical bag which upon deployment is filled with water to form a hydrosphere. A first embodiment comprises a plurality of upper and lower spreaders which form the bag into a spherical shape having a valve at the bottom most portion thereof for entry of water into the bag during oscillatory motion of the hydrophone. A second embodiment comprises a flexible, acoustically transparent, spherical bag which is time-filled with water by a pump to inflate the bag to a predetermined pressure. The hydrosphere forms a large virtual mass of static water around the hydrophone which reduces near field affects due to flow and motion noise and which also operates as a sea anchor.

Abstract: A selected depth mooring system, such as a sensor package or mine, deployable to and maintainable at a precise depth relative to the surface. A cylindrical housing of flotation, submersible and anchor units connected in tandem are sequentially separated and deployed by cable from the surface to moor the submersible unit the desired depth from the anchor unit, and to release the flotation unit after deployment.