Abstract: A disc of piezoelectric ceramic with a plurality of parallel slots cut into a top surface. Another plurality of slots is cut into the bottom surface of the disc with the parallel slots on the top being perpendicular to the parallel slots on the bottom. For one application a shallow keyway slot is cut into the top and/or bottom surface, traversing the already cut slots, to serve as a receptacle for an electrode ribbon.

Abstract: Measuring apparatus for a system which includes a heat source such as a nuclear reactor and a utilization means such as a steam generator connected by first and second fluid conveying ducts in a closed circulation loop. A multi-path acoustic flowmeter in one leg of the loop obtains an indication of volumetric flow rate as well as an indication of the speed of sound in that leg. A multi-path acoustic measuring apparatus in the other leg obtains an indication of the speed of sound in that leg and electronic circuitry is provided for modifying the indications and combining them to obtain total thermal power.

Abstract: A system permitting VT (Variable Time) fuze setting information to be transmitted thereto from a remote fire control source via a microwave link when the fuze is chambered in a gun barrel prior to the firing of an artillery shell to which the fuze is affixed. Sufficient microwave power is initially transmitted to the fuze by means of the barrel acting as a microwave transmission line wherein the microwave power received is converted to a DC voltage which is stored and used to bias the fuze circuitry which subsequently receives binary detonating data AM modulated on a microwave carrier.

Abstract: A cylindrical transducer for providing an omnidirectional beam pattern in one plane and a line radiation pattern in planes normal to the omnidirectional pattern. The cylindrical transducer active element is a radially poled piezoceramic having a surface into which a square thread is spirally cut so that only a pair of electrical leads are needed to excite the whole assembly. In one embodiment the thread is cut entirely through the thickness of the cylinder and in another embodiment it is cut partially through.

Abstract: A dipole hydrophone which includes a piezoelectric bender bar having at the ends thereof two identical disks having high added mass and low actual mass, and a single mass at the center with low added mass and high actual mass. Support wires are connected to the unit at the bender nodes so that movement of the support causes no electrical output. Another configuration includes a piezoelectric bender disk having an annular ring near the edge portion thereof and a single mass at the center of the disk with the ring and central mass having the same relationship as the disk and central mass of the other embodiment.

Abstract: Apparatus for detecting bubbles in drilling mud so that appropriate corrective action may take place prior to a possible blowout. A low frequency acoustic field is transmitted through the drilling mud which causes the displacement of any bubbles rising through the mud. A high frequency acoustic doppler detection circuit then detects movement of the bubbles in accordance with their displacement by the low frequency field.

Abstract: A corner reflector lined with resonant frequency determining hollow gas-filled spheres is interrogated with a plurality of frequencies, including the resonant frequency and the acoustic return is substantially only the resonant frequency. A four-quadrant device is provided and each quadrant of the device is lined with different sized spheres for four different resonant frequencies, and installed according to predetermined geographical coordinates and orientation. With the combination of resonant frequencies, the interrogating vessel can obtain directional as well as identifying information with respect to the device.

Abstract: A sand transport detector which detects the discrete impingements of sand particles on an elongated probe member inserted into the sand. A piezoelectric transducer element is cemented to the probe and produces an output signal when impingement occurs. With an electronic circuit coupled to the transducer, an indication of sand transport may be obtained.

Abstract: An acoustic multi-tone code signal is transmitted through a water environment to a receiver unit which includes a multi-tone code decoder. If the signal-to-noise ratio of the input signal is above a certain threshold, only then will the coded signal be passed on to the decoder which will provide an output control signal in accordance with the particular code.

Abstract: A method of modifying multipath acoustic flow meter output readings by a certain correction factor, based upon the generation of data points utilizing an analytical formula for distorted fluid flow, and a numerical integration technique for obtaining the relationship between individual path flow and a correction factor, for two or more of the paths.

Abstract: A temperature sensor arrangement which utilizes high Q temperature sensitive resonators coupled to an acoustic waveguide. Several resonators, each resonant at a different frequency, are positioned at various locations in a system to be monitored and an acoustic signal is sent down the waveguide. Reflected acoustic energy is examined for the presence of the various resonant frequencies. Since the resonant frequency of each resonator is temperature sensitive, the detected signals provide an indication of temperature at the respective various locations.

Abstract: A system wherein coded signposts on both sides of a vehicle's path are scanned during the course of travel of the vehicle. Scanning out both sides of the vehicle is accomplished with a single light source in conjunction with a mirror system including a multi-faceted rotating mirror, and detection of the signposts on either side of the vehicle is accomplished with the provision of a single detector and single signal processor.

Abstract: Acoustic imaging system wherein signals from a target of interest impinge upon a set of receiving transducers. The transducer signals are processed and form the input signals to a transparent delay line through which is projected coherent light from a laser. Suitable optics and detectors are positioned relative to the projected laser beam so as to produce an output signal that is applied to a CRT to display a range profile or contour map of the target area.

Abstract: A detector of acoustic emissions from a structure includes a piezoelectric element responsive to both compressional wave energy and to shear wave energy from any direction so that the source of the acoustic emission may be determined.

Abstract: A synthetic aperture side-looking sonar system wherein beam formation takes place in two stages, the first being real aperture multiple beam formation and then coherent addition of real aperture beams to obtain the synthetic aperture improvement.

Abstract: An underwater scene is viewed by a TV camera which in place of the conventional blue, green and red filters has three filters with transmission characteristics within the range of colors passed by the water medium, typical filters being blue-green, green, and yellow-green. The three TV signals from these signals are used to energize the conventional blue, green and red guns of a color TV cathode ray tube (CRT).

Abstract: An electrodynamic sensor unit and a drive unit are attached to a member subject to vibration. The sensor unit provides a signal proportional to the vibration velocity, and this signal is utilized to govern the operation of the drive unit, which acts to reduce the vibration amplitude.

Abstract: There is disclosed a direction-sensitive doppler radar particularly for detecting intruders into a protected area which is free of the mechanically controlled parts of the prior art. To distinguish between an intruder and the clutter produced by the movement back and forth of trees or like growth in a wind, the doppler side bands of the clutter produced by the growth moving or swaying in opposite directions are processed so that they counteract each other. The incoming signals, both clutter and from intruders, are converted into I and Q quadrature signals, frequency or sensitivity compensated and passed through a variable bandwidth bandpass filter whose bandwidth is reduced at the low-frequency end as the clutter increases. The I and Q signals are then each converted into quadrature I3 and I4 and Q3 and Q4 signals respectively, and the products I3Q4 and I4Q3 derived and subtracted. The resulting signal produces the alarm if there is an intruder and indicates the direction of movement of the intruder.

Abstract: An optical window is provided, particularly for multispectral or broadband wavelength (visible and infrared) transmission, which is resistant to damage or erosion by high velocity raindrops or other adverse environmental conditions. The window consists of a substrate of material having the necessary optical properties for the desired spectral range, with a cladding or protective layer of material of high resistance to erosion or other damage bonded to the substrate by a glass bonding material. While any suitable materials meeting the optical and physical requirements may be used, the substrate may be a material such as zinc selenide with a protective layer of zinc sulfide bonded to the substrate by a thin layer of a chalcogenide glass.

Abstract: A coherent sampled CMOS readout circuit and signal processor coupled to a CCD shift register operated by a two-phase minority carrier transfer clock system. The invention comprises a multiplex MIS switch, a reverse biased collection diode, an N channel MOSFET reset switch, a P channel MOSFET electrometer amplifier, and a sample and hold circuit, the configuration having four distinct operational timing subintervals within a clock period wherein the charge is shifted from one shift register bit to another and finally to the output bit. This removes the Nyquist noise associated with the reset switch, suppresses switching transients and 1/f surface noise to thereby improve the signal to noise ratio, i.e., dynamic range, for a CCD array and readout system.