Abstract: A piezoelectric embedded monolithic active surface for transmitting a directed acoustic beam comprising a monolithic active surface, a plurality of piezoelectric elements embedded on the surface forming an array comprising, a plurality of coupled frequency pairs comprising, a first primary frequency row extending in a frequency steered direction the first primary frequency row enabled to accept a first primary frequency signal, and a second primary frequency row extending in the frequency steered direction and located adjacent to the first primary frequency row the second primary frequency row enabled to accept a second primary frequency signal, wherein the plurality of coupled frequency pairs repeat in a delay-steered direction and wherein each of the coupled frequency pairs are enabled to accept a time delayed copy of the first and second primary frequency signals.

Abstract: A piezoelectric embedded monolithic active surface for transmitting a directed acoustic beam comprising a monolithic active surface, a plurality of piezoelectric elements embedded on the surface forming an array comprising, a plurality of coupled frequency pairs comprising, a first primary frequency row extending in a frequency steered direction the first primary frequency row enabled to accept a first primary frequency signal, and a second primary frequency row extending in the frequency steered direction and located adjacent to the first primary frequency row the second primary frequency row enabled to accept a second primary frequency signal, wherein the plurality of coupled frequency pairs repeat in a delay-steered direction and wherein each of the coupled frequency pairs are enabled to accept a time delayed copy of the first and second primary frequency signals.

Abstract: An acoustic beam having at least one preset frequency is generated and dited towards a preselected non-linear acoustic reradiator. The reradiator returns acoustic waves having a different frequency. These reradiated waves are monitored, and a preselected parameter is detected in response to the returned reradiated acoustic waves. In a first embodiment, the preset frequency acoustic beam is generated at one or more frequencies and radiated by at least one projector. Upon incidence of the preset frequency acoustic beam, a preselected reradiator generates acoustic waves having a different frequency. The reradiated acoustic waves are used to calibrate a hydrophone. The reradiated acoustic waves can be controlled by the acoustic projector without a wire link.In another embodiment, the non-linear reradiation is caused by the action of a projected beam on cavitation generated by a vessel remote from the projector.

Abstract: A first projector that generates a beam of acoustic energy having a first equency, and a second acoustic projector that generates a beam of acoustic energy having a second frequency are provided. Interaction between the intersecting beams and particles present in the aquatic environment cause radiation of a third frequency at the region of beam intersection. The third frequency acoustic waves returned from the non-linear acoustic radiating area are monitored at a hydrophone, and the travel time of sound from the projectors to the hydrophone is determined. Successive readings can be made at various depths to obtain a velocity profile. Velocimetry can thus be accomplished free from any need to lower a tethered physical velocimeter into the depths.

Abstract: An autonomous underwater acoustic charge deployment buoy that can deploy ustic charges at preselected time periods. The device can operate away from any control vessels or structures. The device comprises a plurality of launch tubes disposed within a frame supported by an elastomeric floatation collar. An electrical control circuit is fastened to the upper surface of the frame to control acoustic charge release times. A hinged door that is held closed by a burn wire is disposed on lower end of each launch tube. Activation of the control circuit causes the burn wire to part, releasing the hinged door. When the hinged door opens, gravity causes the acoustic charge to drop from the launch tube. The device can deploy a plurality of acoustic charges at preselected times remote from control vessels or structures.

Abstract: A voltage measuring device for accurately sensing the AC load voltage at remote, distal end of a long, two-conductor cable, the measuring device comprising a parallel arrangement of an AC source and a DC voltmeter, located at the proximal, source end of the cable, and an AC load in parallel with a passive, DC producing module at the distal, load end of the cable, the passive module further comprising a passive, DC producing voltage divider, the output of which is proportional to the AC load voltage drop.

Abstract: A selectively transparent baffle means for controlling beam pattern dispel or direction, further comprising a plurality of parallel, vertically oriented, compliant tubes each of which attach to one of two header tubes at one end while the opposite ends are open to sea pressure. The headers provide air fill or vent.

Abstract: Apparatus and method for nondestructive detection of loose parts or faulty onds in sound transducers by measuring erratic second-order nonlinear difference-frequency responses of the test transducer to a pulsed high level dual-frequency sound field produced by a high power projector. Such field may be generated by combining a high frequency carrier signal at frequency f.sub.o with a low frequency tone burst signal at frequency f/2 in a double balanced modulator so as to produce the dual-frequency pulse at f.sub.o +f/2 and f.sub.o -f/2. The test transducer converts the dual-frequency pulse into a plurality of linear and nonlinear frequency components including the difference-frequency f.

Abstract: A high power sonar pulse generator driven by a low power electrical motor erein a flywheel, placed in the mechanical system, connects the small motor and large generator. Since the large power output from the pulse generator is required only intermittently, the energy stored in the rotating flywheel allows a small motor to effectively drive the large output pulse generator while a braking effect on the flywheel is used to vary the sonar impulse producing an advantageous FM glide.

Abstract: A summing amplifier which sums and amplifies two input signals and combines them in a single load or output device. It includes a bridge circuit using either 4 NPN or 4 PNP type transistors. Two transformers are used to achieve input relationship. A square wave of different frequency is applied to each of the two input terminals and the sum of the two input frequencies is converted to a three level waveform of constant amplitude but with on-time variations periodic at the difference frequency of the two input frequencies.

Abstract: An acoustic line array which includes a co-axial cable having a center coctor surrounded by a flexible material of low-electrical conductivity. The flexible material is surrounded by a conducting material protected by an external shield. The cable has characteristic impedance which is sensitive to pressure variations in the medium due to a traveling acoustic pressure wave from an acoustic source. Variations in the impedance of the array are used to detect the acoustic source. Alternatively, the line array makes use of discrete sensors placed at suitable intervals along the array. This type of acoustic array eliminates the use of a plurality of wires carrying the electrical signals from the transducer to the storage equipment and elaborate multiplexing techniques.

Abstract: A cavitating parametric underwater acoustic source for generating efficiey acoustic energy at low and medium frequencies. The source comprises a plurality of electro-acoustic transducer elements which are electrically energized in a liquid medium such as water at two or more primary frequencies. Changes in the ambient liquid pressure at or adjacent the transducer cause cavitation in the liquid medium which produces a high degree of non-linearity resulting in the generation of sum and difference frequencies of the primary frequencies in the liquid. The difference frequency is used to transmit acoustic energy efficiently in the liquid medium.