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: A power converter unit includes a pair of switching DC/DC converter secti for positive and negative voltages which incorporate a MOSFET switching arrangement in which a pair of MOSFETs are forced to share the output load current equally, a current limiting arrangement which activates shutdown whenever the current threshold limit is exceeded, and an internal grounding arrangement which minimizes output of current spikes by isolating the switching spikes from the input and output.

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 hydrophone or other acoustic vibration sensing apparatus having a disk circumferentially supported for flexure induced by acoustic vibrations and wound on each side with a flat spiral of optical fiber fixedly attached to the disk side so that flexure of the disk due to the vibrations lengthens the spiral on one side and shortens the spiral on the other side. The spirals are connected as two legs of a fiber optic interferometer to provide an output corresponding to the vibrations while canceling errors due to pressure and temperature effects common to the legs. A pair of the disks and associated optical fiber spirals may be mounted on opposite ends of a body with the outer spirals connected as one interferometer leg and the inner spirals as another leg to cancel differences in the lengths of the legs due to acceleration induced flexure of the disks and to provide double the sensitivity to pressure differential of a single disk.

Abstract: Apparatus for determining the electrical characteristics of a superconductive material in a range of microwave frequencies and in a range of cryogenic temperatures has the material incorporated within a resonant cavity mounted on a cold finger for maintaining the material at a predetermined temperature. A pair of test waveguides extend oppositely of the cavity and terminate in separable waveguide junctions for passage of microwave energy to measure the microwave characteristics of the cavity as affected by the superconductive material. The cavity and test waveguides are enclosed in a vacuum chamber from which the cold finger extends for connection to controlled temperature cryogenic cooling equipment. The chamber also contains a plurality of calibration waveguides which extend parallel to the test waveguides, each calibration waveguide terminating oppositely in separable junctions.

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: The invention is directed to a fluid mixing device in which a jet of first luid is passed through a nozzle having a conical inlet section and a noncircular, elongated, exit section. The jet of first fluid mixes with a second fluid located downstream of the device. In operation, the intersection of the conical and elongated sections produces axial rotation in the first fluid. Intense, three-dimensional, axial and circumferential vortical structures are created. These structures then interact with the high modes of azimuthal instabilities that are common to the elongated configuration. The jet of first fluid evolves into two secondary jets, generating a double shear layer inside the flow. Highly efficient mixing of the fluids, in both the outside and inside (core) segments of the jet, is achieved within a relatively small mixing space.

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 extrudable plastic bonded explosive molding powder is provided and conns about 20 percent by weight ethylenevinyl acetate copolymer and 80 percent by weight PETN.

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.

Abstract: A dual frequency, synthetic aperture, sonar system includes a transmitter r projecting insonifying pings alternatively at first and second frequencies and a linear receiving array carried by a vehicle so as to receive returns from said pings. The first and second frequency returns are separated and subjected to processing in parallel channels where they are resolved into in-phase and quadrature components for subsequent phase-error correction, coherent addition, and synthetic aperture beamforming.

Abstract: A method of remote detection of an electronic device, such as an electronic omb fuze, which employs active electronic elements includes the steps of transmitting a radar beam through an object which potentially encloses a suspected bomb and receiving the reflections of the transmitted beam, using doppler radar techniques to detect signal phase and amplitude modulations, if any, and processing the reflections to provide an output resulting from any detected modulations which would indicate the presence of active electronic elements within the searched object.

Abstract: An omnidirectional hydrophone having an elastic shell which is spheroidal so that the circumference of the shell about different axes changes differentially when the shell is subjected to pressure variations. The differences in circumference are advantageously measured by an optical fiber interferometer having one leg wound about the equatorial circumference of the shell and another leg wound about its meridional circumference. The shell may be an oblate spheroid having the ratio of its major axis to is minor axis greater than about (2-.nu.)1/4, where .nu. is Poisson's ratio of the shell material, so that the shell narrows along one axis and widens along the other when the shell is subjected to a pressure change.

Abstract: The detection, by doppler frequencies in reflected wave energey, of an obt, such as an obstruction on a landing surface approached along a path at a shallow angle to the surface, using doppler frequencies returned from a fixed range. The frequencies returned by the surface and the obstruction are distinguished by their relation to a threshold frequency determined by the velocity along the path and the angle. Returns from the surface as the angle of incidence at the fixed range increases from the initial normal angle of incidence are minimized by selection of the carrier frequency, and clutter is rejected by ignoring a return at the fixed range that does not correspond to a subsequent return at a nearer range.

Abstract: A sonar system having a transmitting transducer adapted for being moved ag a predetermined path, a transmitter for energizing said transmitting transducer, an omni-directional receiving transducer spatially disposed behind said transmitting transducer, a sidewardly and downwardly looking receiving transducer contiguously disposed with said omni-directional receiving transducer, a receiver connected to the output of said sidewardly and downwardly looking transducer, a series connected detector, differentiator, delay, and time base generator coupled to the output of said omni-directional transducer, and a readout connected to the outputs of the aforesaid receiver and time base generator.

Abstract: Ditertiarybutyltelluride and other symmetric dialkyltellurides are prepared from tellurium tetrachloride and metal alkyls in tetrahydrofuran. The reaction product is isolated by filtration followed by vacuum distillation.

Abstract: A sonar system having a transmitter for successively broadcasting a pair of coustical signals having different frequencies, a programmer for determining the times said pair of signals are broadcast, a receiver for receiving said pair of signals after they have been reflected from a target, a programmer for effecting the conversion of said received pair of signals into a continuous unitary electrical signal having variable consecutive time periods which alternately contain the respective frequencies thereof, and a readout for displaying said continuous unitary electrical signal.