Abstract: A water fillable chute, to be employed as a submerged tractor device is cected to a plurality of wire severing grapnels by means of a metallic chain for sweeping command type river mines.

Abstract: An electroacoustic transducer having a truncated hemispheric propagation or esponse pattern is disclosed. The transducer comprises an assembly of fish-bone shaped piezoelectric elements, each characterized by a plurality of rod portions extending from a spine portion. The assembly is pivotally mounted within a liquid filled acoustic window means.

Abstract: A high information rate catacoustic system having a sonar transmitter dised at a remote location from and facing a sonar receiver in such manner that forward-scattered echoes of sonic energy originally broadcast by said transmitter are reflected by and received from the sea floor by said receiver and displayed by a recorder connected thereto as an inverse function of the range from the sea floor to said transmitter.

Abstract: A sonar system is disclosed having signal analyzing circuitry rendering the ystem responsive to objects of a predetermined size. The signal analysis is accomplished by a spectral analysis of the echo signals returned from the objects. In particular, the relative height of adjacent side lobes of echo signals energy returned to the sonar are compared to indicate the size of the object reflecting the signal.

Abstract: A marine mine control wire tagging system is disclosed as including a traitter and a receiver, a mobile underwater vehicle having a launcher mounted thereon, a radio frequency signal tag loaded in said launcher, a sensor and a fire control system for launching said tag upon the detection of said marine mine control wire by the aforesaid sensor. If so desired, said transmitter and receiver may be mounted on a boat which also tows said underwater vehicle to a position in proximity with said control wire.

Abstract: A sonic echo simulator for simulating sonar signals reflected from underwr targets having a transmitter which broadcasts sonar signals through a given amount of water toward a receiver for readout thereat. Prior to broadcast, various characteristics, such as target length, target aspect, target shadow length, range to sea floor, sea floor reverberation, and target highlights are selectively incorporated into said broadcast sonar signals by combined circuits for the timely generation thereof, respectively.

Abstract: Disclosed is an acoustical energy generator having a venturi front section o which is attached a pair of rear tail pipes. A pair of return flow manifolds are respectively connected between said rear tail pipes and said front venturi section at such locations that the static pressure in the former are greater than the static pressure in either of the latter when a fluid is flowing therethrough. Controllable valves are optionally disposed in said return flow manifolds to regulate the fluid flow therethrough, and a freely rotatable flutter valve may be disposed at the common junction of said venturi section and tail pipes to facilitate the rapid transfer and/or cutoff of flow from the former to both of the latter in an alternating manner, and thereby effect a more positive generation of cavitation at a desired frequency of operation. A bridle is connected to the front end of the venturi section and a tractor vehicle is attached thereto by means of a tow cable.

Abstract: Disclosed is a system for locating a wire that is partially submerged wit water and partially extends out thereof which includes a transmitter for broadcasting radio frequency electromagnetic signals, a phase gradiometer for receiving said radio frequency electromagnetic signals after they have been received by that portion of said wire that extends out of said water and re-radiated by that portion of said wire that is submerged therein and for timely producing a pair of output signals in response thereto, a pair of constant output amplifiers for processing said pair of gradiometer output signals to identical useful levels, a phase comparator for determining the phase relationship between said pair of processed output signals, and a readout for indicating said phase relationship. The aforesaid phase gradiometer may be housed in a probe-type of mobile underwater vehicle which is towed by a tractor vehicle in such manner as to cause said phase gradiometer to traverse an underwater course in search of said wire.

Abstract: A sweep device for river mines of the command type is described. The device mploys two spaced, parallel blades which support the sweep device on the bottom of the river as it is towed therealong. The blades constitute laminated cutting elements which provide a signal of the presence of a command wire as it is severed on contact, as well as serve as electrodes for supplying an electric signal to sweep the mine. An electrical circuit is also described to process the signals from the blades, so as to distinguish between small metallic debris and metallic bodies bridging the two blades.

Abstract: A mine sweeping method and related apparatus for achieving at least tempoy passivation of underwater acoustic influence mines, by the generation of particular underwater sounds of progressively increasing intensity. The water is by repetitively injecting into the water individual metered slugs of heated water, which water is heated to its saturation pressure but below the critical point. The metered slugs of heated water may be of the same or of progressively increasing size, i.e. weight, and can be released from a heated pressure chamber into the water from either a stationary array or from an array towed from a moving ship, and at a depth such tht the expanding bubbles, produced by the change of state of the heated water, do not break the water surface. The rapid expansion of the metered slugs produce the desired sound output for temporarily rendering the acoustic influence mines passive by actuating their anticountermine circuits.

Abstract: The echo ranging system of the invention comprises circuit means to diffetiate between shadows cast by objects and the period of time prior to the receipt of the first bottom return, as well as the lack of bottom reverberation for other reasons. Additional circuit means determines if the length of the shadow signals in comparison to their range exceeds a predetermined value. Circuit means are also included to produce a first electrical signal when such shadow signals are received. Further circuitry analyzes the shadow signals for which the first electrical signals were provided and produces a second electrical signal when said object shadow signals exceed in number or length a predetermined value. Additional circuit means are provided to convert said first and second electrical signals to suitable audible signals which may be readily distinguished, one from the other.

Abstract: This invention pertains to the electroacoustic transducer arts and disclo an improved physical construction therefor in which a honeycomb-like member is used to secure both pressure release and thermal transfer for the converting element.

Abstract: A continuous wave, doppler sonar has an underwater towed portion including projector disposed vertically displaced from a multi-element receiving array. Received CW signals are processed for spillover elimination and subjected to phase lock loop tracking filters for reverberation and target doppler prior to target signal detection, thresholding, multiplexing and transmission to the towing portion. The target signals are distributed as to azimuth, recirculated in a memory, and reiteratively displayed in PPl format, with periodic updating.

Abstract: An underwater transient sound generator for broadcasting optimum acoustical onic energy in sea water with an appropriate intensity and frequency spectrum to achieve passivation of acoustical mines. A high pressure bubble is released from a chamber while a resilient diaphragm is simultaneously vibrated, the diaphragm having at least one of its surfaces in contact with the sea water. The system provides an improved pneumatic-mechanical impact sound source that produces a controllable distribution of high power, broad band spectrum acoustical energy, to temporarily inactivate acoustical mines, while masking the noise of the ship as it passes the mine.

Abstract: An underwater acoustic generator comprising a tapered solid positioned in a luid flow to produce a cavitation void. A source of gas supplies the void with gas to produce a resonant gas bubble.

Abstract: A side-looking sonar is provided with the wide angle acceptance characterics of a wide receiving beam together with the high resolution of a narrow receiving beam, while retaining both echo and shadow detection capability, through the use of a plurality of transducers disposed at such angles that their respective narrow beams cross one another at a location between the transducers and the ranges of interest and the distal portions of the beams lie adjacent one another. Individual returns received from the beams as the sonar is moved along a path normal thereto are coherently combined and detected.

Abstract: A doppler compensated sonar systems is disclosed as containing one or more ata processing channels connected through a multiplexer to a like plurality of piezoelectric elements in a reversible electro-acoustical transducer. Each channel thereof includes a transmitter and a receiver, the latter of which includes signal perfecting circuitry and a pair of effectively series connected phase lock loops constituting reverberation and target doppler tracking filters, respectively. Hence, each of said channels effectively process received target signals without any adverse doppler effects being present therein which are then, in turn, read out by any suitable video display. When mounted on a fast moving vehicle, the subject doppler compensated sonar system optimizes the avoidance of hazardous or other objects that may occur in the path thereof.

Abstract: A pneumatic launcher for instrumented objects includes a barrel, a breech mber having a compressed gas reservoir, a pneumatic piston operated valve for discharging gas from the reservoir into the barrel and is characterized by a fail-safe venting feature and a throttling valve for automatically limiting acceleration of the launched object.

Abstract: A self-contained, freely floating, freely operating minesweeper is disclo which facilitates the neutralization of marine mines in rivers, streams, and other water courses. Said minesweeper includes a barrel with a permanent magnet array mounted on the bottom thereof. An internal combustion engine, having a drive shaft and an exhaust output, in mounted within said barrel in such manner that the drive shaft extends through the side wall thereof. A partially fender shrouded paddle wheel is mounted on the end of said drive shaft for rotation therewith, and an exhaust pipe is connected to the exhaust output of said internal combustion engine, with the effluent end thereof located outside said barrel and radially therefrom in such manner as to cause the exhaust gases emanating therefrom to effect rotation thereof. A float collar is partially mounted around the outer periphery of the aforesaid barrel, so as to facilitate the attitude stabilization thereof.

Abstract: An underwater, towable wire detector wherein a pick-up coil is carried in R.F. (radio frequency) signal shield that is positioned by gravity to receive only those emanations receivable upwardly through an R.F. window therein.