Abstract: A magnetometer wherein inductance of a resonant circuit is made sensitive changes in magnetic field to vary an oscillator operating frequency. The magnetometer utilizes a ferromagnetic sensor element that is characterized by high permeability in weak magnetic fields when the element is maintained at predetermined elevated temperatures near the Curie point of the element material and also exhibits a hysteresis curve having a steep slope in the region of field strengths on the order of the earth's magnetic field. The preferred embodiment includes resistive heating of the element and use of substantially pure iron as the element material.

Abstract: An underwater navigation device wherein a flux gate compass provides head difference signals, a doppler navigation sonar provides drift angle signals, which signals are combined by a summer to provide steering correction signals that are displayed by a steering null meter.

Abstract: Relative phase and sensitivity characteristics of individual transducer eents in a long acoustic array are determined by sequentially positioning a transmitting element in predetermined spaced relation to each array element by means of an array holding member and a trough-like spacing member that contains a known transmission medium, driving the transmitting element with a test frequency input signal that is pulsed at a predetermined repetition rate, gating the output signal from the array element under test to an oscilliscope for phase comparison with an adjustably phase shifted version of the input signal, and measuring amplitudes of both input and output signals.

Abstract: An electro-optic modulator wherein a light waveguide is in the form of a film disposed on a prismatic substrate and beneath modulating electrodes. The substrate has opposite end faces disposed at predetermined angles to its longitudinal axis and cooperates with grating couplers on the waveguide to direct an entrance beam through the waveguide and to provide an exit beam along a predetermined path relative, e.g., parallel, to the entrance beam.

Abstract: A sonar system is disclosed which processes received sonic energy echo sils in such manner as to determine whether or not a marine mine or other object of significance is laying on a particular area of sea floor being sonically scanned or searched and, in addition, whether or not said marine mine or other object has a sonic energy shadow behind it. If and when such two conditions are met, an alarm is given to the human operator monitoring the subject sonar system, so as to call his attention to the fact that a target of significance has been acquired.

Abstract: A depressing force in the form of negative lift is hydrodynamically generd on a towed underwater vehicle as a result of fluid in motion passing static fluid separated by a membrane so as to cause a negative pressure zone externally of the membrane. The external negative pressure enhances distension of the membrane into a water foil generating additional negative lift.

Abstract: A helicopter carried, towline recovery buoy system including a package coining a retrieval line, inflatable buoys, and buoy inflating devices. A support and release mechanism releases the package response to dropping of the towline. The buoys and retrieval line are automatically deployed to permit recovery of the towline by grappling from a helicopter.

Abstract: Method and apparatus for mixing hydrogen and oxygen as a noncombustionable ixture of gases which avoids the hazard of a combustible mixing interface are disclosed as comprising a pair of cylinders which timely contains a water solvent within which said hydrogen and oxygen are respectively dissolved under pressurized and refrigerated conditions, in accordance with a predetermined program of operations. Then, the gas-saturated water of one of said cylinders is mixed with that of the other, thereby causing the gases therein to be mixed wthin the mixed water. The resultant gaseous mixture is subsequently separated from said water mixture, dried, and stores as a mixture of hydrogen and oxygen gases.

Abstract: A diving helmet exhaust regulator valve maintains helmet pressure substanlly constant in a push-pull system wherein breathing gas is supplied under pressure (push) at a constant rate and respired gas is exhausted to a low pressure (pull) conduit for return to a regenerator. The regulator valve is characterized by a throttling valve member operated by a piston that is acted upon by ambient sea pressure and helmet pressure independently of pressures in the upstream exhaust passages, or of exhaust flow rate.

Abstract: A connection for releasably securing a diving helmet to a suit through the se of nestable upper and lower ring members having mating cylindrical portions sealed by an O-ring. A tongue and slot serve to orient the helmet during donning and cooperate with two sets of pintles and gudgeons disposed 120.degree. from one another to secure the ring members together.

Abstract: A low-noise, stage-stabilized, direct-coupled, single-ended amplifier cirt is disclosed which has a unique feedback network combined therewith in such manner that degenerative alternating current and substantially constant direct current feedback signals are supplied thereto, so as to effect an exceptionally steady amplification factor therefor over a very broad frequency response band.

Abstract: Phase detection between interfering light beams in an interferometric sys is accomplished by frequency shifting the reference beam prior to combination with the interrogation beam and electro-optically scanning the resulting pattern to produce an FM electrical signal having the shift frequency as a carrier and the interrogated parameter as the modulation data. A phase lock loop is responsive to the FM signal to provide a D.C. signal that is analogous of rate of change of the interrogated parameter with scan, and which is integrated to provide an output voltage signal that is proportional to the interrogated parameter and the corresponding optical phase difference. The method and system employing it are operative for a wide range of phase differences including multiple fringes.

Abstract: A vehicle carried metal object sensing system wherein sensing of magnetic elds of different polarity or of ferrous and non-ferrous objects results in distinctive colors on a cathode ray tube display. Deflection signals are generated in accordance with vehicle travel and field scan to provide successive frames of a map-like display.

Abstract: A variable area jet nozzle construction capable of blocking flow in favor another nozzle in a vertical or short take-off aircraft utilizes a balanced two-dimensional flap that is pivotable about rollers and movable, along curved tracks cooperable with the rollers, to assume a plurality of nozzle area varying or blocking positions under the influence of linear hydraulic actuators.

Abstract: An improved microphone assembly for use in a diver's mask or helmet and wh is characterized by a substantially flat frequency response at pressures from 1 to 30 or more atmospheres of breathing gas. A silicone rubber coated piezoelectric diaphragm is mounted by its periphery in a cylindrical housing with both sides of the diaphragm exposed to ambient gas pressures. A ground plate is mounted in said housing with one side in spaced relation to the diaphragm and having on the other side thereof a preamplifier and automatic gain control circuit electrically connected to the diaphragm and encased in waterproof potting compound.

Abstract: A portable pulsed signal generator which generates a low-frequency, high-ered signal from a constant direct current, low power source is disclosed as including an inverter for driving a plurality of motors which, in turn, actuate control switches by means of cams and cam followers associated therewith. A potentiometer driven by one of said motors, in turn, effectively controls the output of a direct current amplifier, with the varying direct current output signal therefrom having the alternate half-waves thereof polarity reversed by switch controlled relays, the switch of which is timely actuated by one of the aforesaid cams, cam followers, and other switches, respectively, so as to produce a low-frequency, high-power, substantially alternating current signal. After appropriate transduction said low-frequency, high-power, substantially alternating current signal may be employed for sweeping mines.

Abstract: An open circuit heat engine, utilizing air as the working fluid, is described wherein an intermittent flow heat exchanger recovers heat energy from spent air to add heat to air prior to expansion into the working chamber.

Abstract: A stabilizing drag and spin inducing device is described for an instrumen underwater vehicle. A flexible plastic disc having a central aperture and segmented into angularly offset vanes is pressed onto the vehicle probe section with resulting distortion causing the disc to assume a conical configuration. The vanes flex to increase drag on descent and decrease drag on ascent, while also assuming spin inducing pitch.

Abstract: A voice operated relay system is disclosed which includes signal processing ircuitry for receiving and discriminating with respect to human speech signals and for actuating a relay in response thereto. A power supply test is also included, as well as circuitry for preventing relay drop out due to input speech hesitations. The preferred embodiment of the subject system is disclosed as a means of enabling a cassette recorder and for causing it to record said human speech signals at either near or remote locations.

Abstract: An array of circular, acoustic projecting and receiving transducers is deibed, including a stainless steel baffle plate in which the transducers are mounted, each comprising a stainless steel cup containing a disc-shaped piezoelectric element set in low impedance material and covered by a water impedance matching window. Capacitive and inductive tuning means is provided between each receiving transducer and its associated electronics.