1. A channel defining system for aiding the navigation through a body of er of a vessel equipped with a high resolution pulsed catacoustic system adapted to scan the bottom in range abeam of the vessel comprising An elongated buoyant ridge-like strip of acoustic reflecting material extending lengthwise of the channel on the channel bottom and laterally spaced from the center line of the channel by a substantially constant known distance, and Anchoring weights secured to said strip at spaced posi...

3. An underwater acoustic device comprising in combination an annular support member, a vacuum backed circular piezoelectric plate mounted on said support member, a substantially mechanically rigid wall element mounted on said support member and forming with the front face of said plate an enclosure, and an acoustic energy propagating liquid filling the free space within said enclosure, said liquid at all times being under a pressure no greater than atmospheric but not less than the vapor pressu...

1. An underwater acoustic device comprising in combination a substantially igid front wall member of sound transparent material, a rear wall member of piezoelectric material spaced back of said front wall member in generally parallel relation thereto and substantially coextensive therewith, said rear wall member comprising the front face of a cathode ray tube means joining said wall members together at their edges to form a fluid tight enclosure, a liquid filling said enclosure, a liquid filled ...

1. A catacoustic system for detecting the intrusion of a body in an object ield under a water surface at a harbor entrance or the like comprising a high resolution sonar apparatus including a submerged transducer having a vertically oriented fan shape directivity pattern directed at an object field athwart the harbor entrance and having its principal axis slanted towards the water surface, means for periodically pulsing said transducer to radiate pulses, a display medium, and means for receiving...

1. A self-propelled underwater attack deviation device comprising in combtion: A cylindrical casing adapted for launching from a submerged submarine, A jet propulsion plant within said casing and having a discharge nozzle at its downstream end through which passes jet propulsion gaseous discharge, Said discharge nozzle extending beyond and being of smaller cross section than said casing, A removable end cap telescoped onto said casing in enclosing relation to said discharge nozzle and adapted to...

1. An acoustic barrier for detecting and classifying a body intruding into a protected volume of water comprising a high resolution active sonar apparatus including a transmitting transducer submerged in the protected volume of water and having a vertically oriented fan shape directivity pattern with its principal axis slanted toward a bounding surface, means for rotating said transmitting transducer in azimuth about a vertical axis, means for pulsing said transmitting transducer t times per sec...

1. A transducer for translating compressional waves in a liquid medium into lectrical waves in an electric circuit and vice versa comprising an elongated transducer element having a spherically concave active face disposed with its smaller dimension between two circles of latitude spaced apart in a hemisphere a distance substantially equal to the wavelength in the liquid medium of a predetermined operating frequency.

1. A high resolution sound wave detecting system having a fan-shape beam of receiver sensitivity comprising a pair of transducers having elongated active faces coplanar and in end to end relation, an output signal channel for each transducer, means including two local oscillators of different frequencies connected to heterodyne against each other for producing timing pulses having a repetition rate equal to the frequency difference of said oscillators and individually against the output signals ...

An underwater vehicle having a water-tight, disconnectably-sectioned, prere-resistant, rugged, hull for carrying electronic instrumentation and other apparatus, a stabilizing tail section for altitude control, a manually adjustable negative-lift wing, and an adjustable bridle for the towing thereof by any suitable tractor vehicle.

1. An acoustical decoy system for protecting a marine carrier vessel from attcking torpedo, comprising in combination: a marine carrier vessel to be protected, having a longitudinal axis substantially paralleling the direction of travel thereof; an electrical signal generator disposed in said marine carrier vessel; a phase shifter disposed in said marine carrier vessel and electrically connected to the output of said electrical signal generator; a first electroacoustical transducer disposed remo...