Abstract: A cathode for a secondary emission structure comprised of a superconductive material is described. In one embodiment the cathode comprises a layer of a superconductive material such as yttrium barium cupric oxide, or rare earth substituted neodymium cupric oxides. The layer may be bonded to a metal electrode or preferably the cathode consist of a superconductive or conductive oxide. The use of a superconductive material provides a cathode having suitable secondary emission characteristics and, furthermore, which being conductive at room temperatures, as well as, temperatures of operation of the cathode, obviating the need for a use of a very thin film of a secondary emission material.

Abstract: A voltage variable attenuator is described including a quadrature hybrid coupler having an input port, an output port, a first reflective port and a second reflective port. The voltage variable attenuator further includes a first and a second impedance network, the first impedance network connected to the first reflective port of the quadrature hybrid coupler, the second impedance network connected to the second reflective port of the quadrature hybrid coupler, each impedance network including a first RF propagation network having a first end connected to the respective reflective port of the quadrature hybrid coupler. Each impedance network further includes a second end of the first RF propagation network connected to a field effect transistor having a drain electrode, a source electrode and a gate electrode, the drain electrode connected to the second end of the first RF propagation network.

Abstract: A ring laser gyro uses means for shaping the gas flow, which inevitably develops as a result of a DC discharge, to optimize the effect of the Fresnel-Fizeau drag on the output signal of the gyro. In one embodiment, a sufficient component of the gain medium flow is provided to produce a substantially constant Fresnel-Fizeau component of the output signal even in the presence of variations of the discharge current. In another embodiment, a sufficient component of gain medium flow is provided to substantially eliminate the Fresnel-Fizeau component of the output signal at a predetermined level of discharge current.

Abstract: A SAW device such as a resonator includes a surface supporting surface wave propagation and a pair of aluminum transducer elements each coupled to said surface wave propagation surface. Each aluminum transducer element is doped with a predetermined amount of silicon. Frequency shifts which result from exposing the SAW device to high temperature cycles as often encountered when packaging the device are reduced, since the silicon present as a dopant in the aluminum will provide an effect on frequency which can be taken into consideration during design and fabrication. These frequency effects will dominate any frequency effects which may result from silicon migration from the substrate to the transducers as a result of the thermal cycling encountered during sealing of the SAW device.

Abstract: A low vibration sensitive SAW device includes a first quartz substrate having a pair of opposing surfaces, each surface which supports surface wave propagation. A pair of transducers are coupled to each of said surface wave propagation surfaces providing a pair of surface wave devices on opposing surfaces of the substrate. Each surface wave propagating surface is covered by a matching quartz cover and a glass-frit seal to provide a three piece all-quartz package. The pair of devices are connected together in parallel generally externally from the package, and when the dual device package undergoes vibration in a direction perpendicular to the surface wave propagation surfaces, one surface of the substrate will be subjected to a tensile strain field, whereas the opposite surface of the substrate will be subjected to identical but opposite direction strain field that is compressive.

Abstract: A semiconductor structure having an active layer formed over a first surface of a substrate. The semiconductor structure includes an electrode formed over a first surface of the structure. A conductive layer is formed over a second surface of the substrate. A conductor section passes through the semiconductor structure between the electrode and the conductive layer. The conductor section includes two conductive elements, one having a first end connected to the electrode and a second end terminating in the semiconductor structure; and the other conductive element having a first end connected to the conductive layer and a second end connected to the second end of the first conductive element. The second end terminates at, or in, an etch resistant layer disposed in the semiconductor structure between the active layer and the substrate. The method for forming the conductive sections includes etching the second via hole from the second surface of the substrate until the etching reaches an etch resistant layer.

Abstract: A microwave oscillator is shown to include an oscillator having an output and a control port and a feedback circuit disposed between the output and the control port of the oscillator. The feedback circuit includes a modulated laser, having an input and an output, the input responsive to a portion of a signal from the output of the oscillator and a photo detector having an input and an output, the input of the photo detector responsive to a signal from the output of the modulated laser delayed by a predetermined amount of time. The feedback circuit further includes a detector having a first and a second input and an output, the first input of the detector responsive to a signal from the output of the photo detector, the second input responsive to a portion of the signal from the output of the oscillator shifted in phase to be in phase quadrature with the signal at the first input of the detector and the output of the detector coupled to the control port of the oscillator.

Abstract: Method and apparatus for bending serpentine heat exchanger tubes using a split bend die having a relatively short upper die section with a straight back end. After the tube is bent in conventional manner using a clamp die and a pressure die, the bend die is split along a shaft and rotated through a predetermined angle to position the straight back end substantially parallel to a straight segment of the tube at the output of the bend die. The input segment of the tube is then moved next to the shaft in preparation for rotating above the input segment to raise the output segment above the upper section of the bend die. Such lateral motion reduces the segment spacing required for clearance of the upper section. Other features for reducing the spacing are providing an indentation on the shaft, angling the back end with respect to the sides to provide a minimum length, and truncation an upper portion along the back end.

Abstract: A digital-to-analog converter switch provides substantially equal propagation delays for both high-to-low and low-to-high transitions of the binary input signal. A ground path transistor and an output transistor are connected to a common node and operated in different states of conduction as determined by the gate voltage on the ground path transistor. A substantially constant current is fed to the node and is either switched through the output transistor or the ground path transistor. In order to compensate for unequal propagation delays in switching the current on and off through the output transistor, additional mimic transistors are provided between the binary input signal and the gate of the ground path transistor. Therefore, transitions in both directions involve one fast and one short propagation delay.

Abstract: A pair of crystallographically matched piezoelectric substrates are sealed together to provide a package for a SAW device. A sealant material including a glass frit is deposited on a selected portion of a first one of the pair of substrates. The substrate having the sealant material is then heated to a temperature which is substantially below the glazing temperature of the sealant material to dry the sealant material. The substrate having the dried sealant material is heated a second time at a temperature just above the softening temperature of the glass frit to glaze the glass frit component with other components of the sealant material being driven from the glass frit during the heating cycles. The substrate having the glazed frit and the other remaining substrate are then mated together in a predetermined manner.

Abstract: A ring laser gyro uses a nonplanar path having at least one plane of mirror symmetry and two pathlength control mirrors in order to reduce scatter variations occurring during the operation of the laser gyro. The mirrors used to produce such path are fixed to an isotropic supporting block having passages therein that define the path segments and the mirrors are moved out or in by the expansion or contraction of the block. The two pathlength control mirrors are disposed diagonally opposite each other on the plane of mirror symmetry, and are placed on substrates whose positions are controllable, each substrate being coupled to means for controlling the positions of the substrates as a function of the pathlength. With such a mirror configuration, the pathlength may be held constant by a suitable control means and the relative movement of the mirrors constrains movement, with respect to the mirrors, of the beams circulating in the path to directions perpendicular to the planes of incidence on the mirrors.

Abstract: A marine autopilot having a deadband feature to reduce ineffectual rudder movement and unnecessary wear on the rudder and associated drive apparatus. In a first deadband operation, four deadband values are computed based on various parameters in order to provide optimum system performance and circuit redundancy. The deadband values are a function of the maximum allowable heading error, the maximum allowable angular velocity of the vessel, and the vessel speed. A second deadband operation compensates for noise introduced into the autopilot system by the speed sensor, compass, and roll sensor.

Abstract: A portable underwater mount for magnetic and electric field sensors. The mount has a gimbal-like structure comprising a ball member having a mounting flange for coupling to the magnetometer. The ball member is cast from polyurethane with Teflon powder suspended therein, providing a substantially frictionless surface. The ball member is disposed over a support platform having a spherical contour so that the weighted sensor positions itself to true vertical. A collar having a lock terminating in the support platform rests over the ball member so that once the sensor is oriented to magnetic north, the lock is engaged to secure the sensor in true vertical and magnetic north positions.

Abstract: A fishfinder having a real time or A-scope display with a numerical readout indicating the diameter of the transducer beam on the bottom of the water body. Further, an indicia indicating the position of the boat and downwardly diverging lines corresponding to the transducer beam are overlaid on the display.

Abstract: Apparatus and method for removing unwanted components of a signal received from a radar transmitter. The unwanted components lie in a clutter Doppler frequency band. Such components are removed by first sampling the received signal at a rate sufficient to cause components of the received signal in the clutter Doppler frequency band to be validly sampled and components of the received signal in a desired target Doppler frequency band to be invalidly sampled. A signal equivalent to the values of a polynomial fit to this sampled signal then provides an estimate of the unwanted clutter components. This estimate is subtracted from the original received signal to provide a signal with the unwanted clutter components removed. A significant improvement in receiver sensitivity as well as a reduction in dynamic range requirements of a post detection digital signal processor is achieved through the use of this invention.

Abstract: A method for increasing the optical transmission characteristics of zinc sulfide in the visible and infrared portions of electromagnetic spectrum is described. Materials such as metals and, in particular, transition metals are diffused through the zinc sulfide material over a duration of time sufficient to cause the material to turn substantially water clear and substantially colorless.

Abstract: A lightweight patch radiator phased array antenna having a single layer patch construction on an artificial dielectric, such as syntactic foam, which achieves a factor-of-ten weight savings over an array constructed with conventional materials. An additional sixty-five percent weight reduction is achieved by cutting away the dielectric material down to the array antenna's ground plane everywhere except under the patch radiator. This construction allows placement of a thermal control material over the patch and ground plane for space applications.

Abstract: A switchable, dual channel frequency converter is provided. The converter includes a semiconductor body having formed as a monolithic microwave integrated circuit: a pair of input signal channels; a pair of output signal channels; and, a mixer and multiplexer means, disposed between the pair of input signal channels and the pair of output signal channels, for converting the frequency of signals fed to the pair of input signal channels to a different frequency and for directing the frequency converted signals to the pair of output signal channels selectively in accordance with a control signal. The mixer and multiplexer means includes: a pair of mixers coupled to the pair of input signal channels and a common local oscillator signal; and a multiplexer network. The mixers covert the radio frequency of the signals in the pair of input signal channels into a corresponding pair of intermediate frequency signal channels.

Abstract: A sonar system is provided for mapping the bottom of a body of water to identify a submerged foreign object. A sequence of the sonar pulses is transmitted and directed toward the bottom. The mapping is formed from a sequence of echo returns. Each one of the echo returns is produced as a range scan in a range direction response to a corresponding one of the transmitted sonar pulses. The sonar system stores signals representative of the intensity of the echo returns in a two dimensional array of pixels. Each one of the pixels represents the intensity of the echo return at a predetermined range position from the system in the range direction and a predetermined cross-range position from a reference position of the system in the cross-range direction.

Abstract: A transmitter/receiver system is provided wherein a transmitter of such system produces a transmitted signal frequency modulated in accordance with the level of a modulating signal and a receiving antenna has an output thereof coupled to a receiver through a switch means, for coupling or inhibiting signals received by the receiving antenna from passing to the receiver selectively in accordance with the level of the modulating signal.