Pressure responsive clasp

Abstract

An underwater acoustic surveillance system for obtaining data related to nd sources of interest in a large geographic area over long periods. A number of acoustic sensors are dropped from an aircraft for placement on the bottom of the sea at known locations. Each sensor automatically deploys a parachute to retard the descent in the air. A parachute riser weak link releases the parachute upon immersion in the water, and a latch operable at a preselected depth allows cylindrical staves to spread apart and form a stable platform on the bottom from which a hydrophone suspends and an acoustic projector tethers. A web-like flow shield unfolds between adjacent staves of the platform to provide additional retardation during the descent in the water and to reduce hydrophone noise due to water currents at the bottom. A water-activated battery at the lower extremity of each stave ensures upright orientation of the sensor when it reaches the bottom, and provides electrical power for storing and transmitting acoustic data. Acoustic data stored in the sensor is retrieved by a sonobuoy deployed on the surface near the previously recorded location of the sensor. An r.f. interrogating signal from the aircraft is acoustically relayed by the sonobuoy to the sensor and acoustic data returned through the same communication media to the aircraft. Thus, large geographical areas may be synoptically monitored for sound sources of interest over long periods and the acoustic data quickly and economically retrieved.