Abstract: An improved system is disclosed for calibrating acoustic pressure-sensitive transducers, particularly hydrophones, down to frequencies in the sub-Hertz range. A transducer under test and a reference transducer, both electrically connected to a voltage measuring device, are mounted in aligned proximity to each other upon a pivotal rocker arm immersed in a water tank. A cam and follower unit driven by a motor oscillates the rocker arm so that the transducers are moved through a vertical displacement equivalent to the desired fluctuation of hydrostatic pressure. As a result, calibrations down to 0.01 Hz are achieved.

Abstract: An acoustic telemetry system and technique are disclosed for remotely meaing the underwater depth and descent rate of a hydrographic package. Analog signals indicative of hydrostatic pressure exerted on the package and related to its underwater depth are periodically sampled and converted to an N-bit digital word representative of the value of pressure. Each bit of the digital word operates one of a plurality of tone generators of different acoustic frequencies in a narrow band, and the outputs of the tone generators are combined with a reference tone continuously generated to permit resolution of Doppler shifts. Acoustically projected through the water to a remote hydrophone, a composite signal representative of the combined tones is corrected for Doppler shifts by translating the frequency of the signal in accordance with shifts detected in the reference tone.

Abstract: An electro-optical display system, particularly useful aboard aircraft carriers, is disclosed for remotely aiding a pilot in the landing of an aircraft. A conventional radar receiver continuously tracks the aircraft and produces a digital data signal indicative of aircraft slant range and elevation angle. The digital data signal is provided to a signal processor governed in accordance with either of a pair of control guidance algorithms to produce a control signal indicative of the magnitude and direction of an error in the appropriate descent rate of the aircraft. Based upon the control signal, a display driver produces a plurality of drive signals for energizing discrete light cells in vertically-oriented arrays as a visual indication of the descent rate error for appropriate corrective action by the pilot.

Abstract: A signal processing system and technique is disclosed for detecting the pence of a desired frequency signal particularly that of a sine wave, in a noisy environment. The signal mixed with noise is received and analyzed by a Fast Fourier Transform spectrum analyzer the output of which is indicative of instantaneous signal phase. The output of the spectrum analyzer is digitally processed to produce a series of average instantaneous signal values based upon the instantaneous signal phase and a statistical estimate of its rate of change, the values being representative of the relative signal strengths for a progression of phase reference values between 0.degree. and 360.degree.. The desired signal is detected when an average instantaneous signal value exceeds a threshold value determined empirically based upon a certain probability of detection and false alarm rate.

Abstract: A DICASS test set utilizes a microcomputer to process infromation from an put and a down link section, generate the appropriate control logic for all the various electronic sections and format the appropriate output data for the output in uplink sections. A keyboard is provided from which an operator can input data the controller. A display and printer is provided to which the controller outputs information to the operator. The down link section consists of a UHF receiver, envelope detector, timer, filter bank, decoder, frequency counter. The uplink section consists of a reverberation simulator, a signal synthesizer, bearing, echo level and sea state controllers, three separate noise sources, multipliers and summing circuitry.

Abstract: A hand-held welding torch is disclosed having a pair of foldable handles to ermit maneuvering of the torch in confined spaces. The torch is of the type having a non-consummable electrode radially mounted on a longitudinal shaft which can be inserted into the bore of a tubular member and rotated so that the tip of the electrode moves over a circular path around the axis of the tubular member. In one preferred embodiment, a front handle is coupled to a spring-loaded collet having an expanded end and mounted for axial movement about the shaft upon actuation of the front handle. A set of radially-projecting jaws pivotally mounted immediately about the collet are spread outward to positively grip the bore by movement along the expanded end so that the torch is properly positioned in substantially the center of the bore and supported therein during rotation of the electrode.

Abstract: A balanced preamplifier is disclosed for impedance-coupling an audio signal source, such as a microphone, to a differential amplifier. In one embodiment, the preamplifier comprises a first stage wherein a pair of complementary bipolar transistors are connected in a common-base configuration and coupled to a low-impedance microphone so that the microphone signal is appied to the respective emitters of the transistors and transformed to an appropriately higher impedance level at the respective collectors thereof with common-mode passage of external and internal noise. A second stage including a complementary pair of bipolar transistors in a common-emitter configuration is coupled to the first stage for greater power and voltage amplification requirements.

Abstract: A water-displacing paint is disclosed for coating metallic surfaces in hu environments to prevent corrosion. The paint comprises controlled proportions of a silicone alkyd resin to serve as a binder and physical barrier, solvents including ethyl acetate, aromatic mineral spirits and 1,1,1 trichlorotrifluorethane for ensuring water immiscibility, a petroleum sulfonate to inhibit corrosion and aid surface absorption, and an organo-titanate of isopropyl tri-titanate to promote surface adhesion. Selected amounts of titanium dioxide and zinc molybdate are included as pigments in one effective example of the paint to provide it a white color. Alternate colors may be produced conventionally by adding standard tinting pigments in amounts sufficient to yield the desired color.

Abstract: A stretch-staging method is disclosed for straightening continuous fiber columns impregnated within a resin-based tape material to increase the strength and reliability of the material. The tape material is supported about the circumference of a half-cylindrical fixture and separated therefrom by a thin lubricating film to reduce surface friction. Loads of substantially equal weight are longitudinally applied at opposite ends of the tape material about the fixture, and the combination is heated in an oven to an elevated temperature for a predetermined period of time thereby stretching and staging the tape material so that distorted fiber columns are straightened and retained in a straightened condition as the resin is advanced.

Abstract: A system for time-compressing radar video is disclosed to improve the grac presentation thereof on a CRT display. Quantized input video is pipelined as cell pairs into and out of a pair of parallelly-arranged memory banks by means of input and output latches. The memory banks are controlled having alternating read and write modes which are interchanged in synchronism with the video scan period so that a preceding scan is read out of one bank at a controlled read clock frequency while a current scan is written into the other bank at a fixed write clock frequency, the degree of video compression being determined by the ratio of the read-to-write frequencies. A pair of series-connected rate multipliers each are fed 6-bit rate words for varying the read clock frequency on either a linear or non-linear scale.

Abstract: A G-protective seat is disclosed for disposing an occupant within a vehicle n a supine tucked posture during high acceleration loading substantially along the Z-axis of the vehicle. At the onset of high Z-axis acceleration, a pair of pivotal leg support members are actuated to fold the legs of the occupant upwardly thereby drawing the knees up to the chest of the occupant in an intermediate tucked position. With the occupant in the tucked position, the seat rotates upward about an axis substantially defined by the occupant's eyes into a supine position for the duration of the high acceleration loading.

Abstract: An automatic exposure control system is disclosed for TV cameras, particuly those of the active type wherein a pulsed light source provides scene illumination for the camera. The control system includes a major control loop wherein an instantaneous photocathode current signal is time-separated from the total sensor signal of an image tube and integrated to provide a real-time measure of the total instantaneous light input upon the photocathode of the tube. When the total light input reaches a predetermined exposure level, a pulse is generated for gating off the image tube via a high voltage supply therefor so that a constant effective exposure is provided the photocathode. Peak levels of the photoelectron current are used to vary the amount of light entering the system and a conventional video detector is included to regulate the photocathode voltage thereby permitting a relatively constant video output signal to be maintained throughout a wide range of input light conditions.

Abstract: An improved dynamic seal for the longitudinal slot in a pressurized cylin of an aircraft catapult system having a shuttle adapted to travel at high speed through the slot. The seal includes a flexible, elongated sealing strip extended along the slot in sealing relation therewith to close the cylinder, and a series of ball detents mounted along the length of the slot on each side thereof for urging inwardly against the sides of the sealing strip thereby providing support for the strip throughout the length of the cylinder. When the shuttle, adapted to guide the strip internally of the cylinder as it passes therethrough, travels through the slot, the ball detents maintain the strip in sealing relation with the slot thereby preventing whipping of the strip forwardly of the moving shuttle.

Abstract: A pneumatic system for launching aircraft wherein an elongated frame having pressurized interior chamber is volumetrically related and communicatively connected to a longitudinally-slotted cylinder supported within the frame so that expansion of air into the cylinder produces a desired thrust pressure therein that is equalized by the residual pressure external of the cylinder within the chamber. A piston member slidably contained within the cylinder is adapted to receive the compressed air and is connected to a shuttle for accelerating the aircraft to be launched. The shuttle is releasably restrained at the rearward end of the cylinder and is adapted to travel longitudinally through the slot which is dynamically sealed by a flexible strip as the shuttle passes through the slot to preserve thrust pressure within the cylinder.

Abstract: A launching system for lightweight aircraft includes a shuttle adapted to rry the aircraft and slidingly mounted to a launching frame along a track that guides launch direction. A piston rod is concentrically mounted within a launch tube parallel to the track and is adapted to receive pneumatic pressure at the inward end thereof for driving the rod longitudinally outward of the tube during the launch stroke of the system. A crosshead having a pair of rotatable sheaves mounted thereon is rigidly connected to the outward end of the piston rod and slidingly connected to the track so that the crosshead moves along the track in conjunction with the longitudinal movement of the rod.

Abstract: A coating composition for protecting metal surfaces from corrosion having ntrolled proportions of an alkyl ammonium alkyl phosphate and a high molecular weight petroleum sulfonate to inhibit corrosion, silicone and silicone alkyd resins to provide a physical barrier, trichlorotrifluoroethane and an aromatic hydrocarbon as solvents, and isopropyl alcohol as a coupling agent. An ethyl cellulose thickener may be added to the composition to increase its viscosity and reduce vertical run-off of the coating. The composition displaces water and moisture on the surface to be coated and deposits a clear, flexible, non-tacky film particularly resistant to abrasion.