Abstract: A circuit for increasing the slew rate of linear amplifier circuits. The circuit comprises two NPN and PNP transistor pairs arranged so that when the voltage level difference between the amplifier output and input voltage exceeds the base to emitter voltage of such transistors, the circuit is activated. The circuit provides a current proportional to such voltage difference in order to speed up the charging or discharging of the slew rate determining capacitance.

Abstract: An RF switch circuit includes a waveguide transmission line having an input port, an output port, a first wall having a first cavity disposed therein and a second wall having a second cavity disposed therein with the first and second cavities being aligned along a centerline of the waveguide transmission line and means for providing a substantially short circuit impedance characteristic between the first cavity and the waveguide transmission line to RF signals propagating along the waveguide transmission line. The circuit further includes an electrically conductive member disposed in a first region of the second cavity, a diode having a first electrode disposed on a first surface of the electrically conductive member and an electrically conductive post having a first end disposed in the first cavity and having a second end disposed in the second cavity with the second end of the post electrically contacting a second electrode of the diode.

Abstract: A track and hold circuit for producing an output voltage having a level related to the voltage level of an input voltage fed to the circuit during a track mode and for maintaining the level of the output voltage constant during a hold mode. The circuit includes a current source and a capacitor with the capacitor being charged with the current or discharged selectively in accordance with the level of the input voltage relative to the level of the output voltage to produce at the capacitor the voltage related to the voltage level of the input voltage. Current from the current source is directed away from the capacitor during the hold mode in order to reduce the effect of charge stored during the track mode from slowing the transition from track mode to hold mode operation.

Abstract: A radar system is shown to include a transmitter for transmitting a pulsed electromagnetic signal having a frequency less than 500 Hz and a receiver for receiving a (scattered) reflected signal provided from the pulsed electromagnetic signal (scattered) reflected from an anomaly below the surface of the water. The radar system further includes a switch for inhibiting the receiver from receiving a reflected signal provided from the pulsed electromagnetic signal reflected from the surface of the water and a signal processor for controlling interoperability of the transmitter, the receiver and the switch. With such an arrangement, a radar system is provided for detecting anomalies such as a wake of a moving vessel (if and when this produces a conductivity anomaly), or a plume of oil beneath the surface of water.

Abstract: A fastener assembly is shown including a cylindrical support structure with a bore provided partially therein, the bore having a wall surface with a slot, and a bushing, disposed within the bore of the cylindrical support structure, having an end and an outer surface with a slot therein. The bushing further includes a bore with a first portion having a first diameter and a second portion having a second different diameter, the bushing also having a pair of tangs extending from the end. The fastener assembly further includes a nut, partially disposed within the second portion of the bore of the bushing, the nut having an outer surface with a pair of lugs disposed on the outer surface to engage the pair of tangs of the bushing and a pin disposed juxtapositional the slot of the wall surface of the cylindrical support structure and juxtapositional the slot of the bushing.

Abstract: A system for providing advance warning of underwater navigation hazards that threaten safe ship passage is provided. The system includes a sonar transmitter/receiver adapted for mounting on the ship in a forward looking direction. A processor, in response to sonar returns produced by the sonar transmitter/receiver, produces a sonar produced slope profile of a region of the sea bottom in front of the path of the vessel. A memory stores a slope profile of the region of the sea bottom in front of the vessel, such profile being developed from charted depth data. The stored charted depth data developed slope profile is compared with the sonar return produced slope profile to determine whether the sonar produced slope profile and the charted depth data slope profile are consistent with each other.

Abstract: A method of processing IR signals from a repetitively scanned array of photovoltaic cells is shown to consist of the steps of: (a) subtracting IR signals received on successive scans to produce response signals corresponding only to IR signals from moving or scintillating objects; (b) generating inhibiting signals for IR signals from the edges of wind-driven clouds or from scintillating objects; and (c) inhibiting those response signals that are from the edges of moving clouds or scintillating objects.

Abstract: A gas surface range having a downdraft ventilation system with automatic shut off during ignition. A relay is activated by current flowing to the spark coil of the electrical igniter, and has contacts connected in series with the blower motor of the downdraft system. Thus, the downdraft system is disabled during attempted ignition, and is automatically enabled at the completion of ignition.

Abstract: A radio frequency energy radar system having a transmitting antenna system for transmitting and directing CW radio frequency energy toward a target. A receiving antenna system, adjacent to the transmitting antenna system, receives portions of the transmitted CW radio frequency energy reflected by the target. The receiving antenna system including a plurality of antenna elements disposed along a path and arranged to provide an antenna pattern having a main lobe antenna pattern directed toward the target and adjacent side lobe antenna pattern. A septum is positioned between the transmitting antenna and the receiving antenna, for shielding unwanted portions of the transmitted CW radio frequency energy from passing directly from the transmitting antenna to the antenna elements of the receiving antenna The shielding means terminates along an edge positioned in a region forward of the antenna elements.

Abstract: A microwave power combiner includes a first plate having disposed in a first surface thereof a first plurality of grooves and a second plate having disposed in a first surface of said second plate a second plurality of grooves, with said second plate being mated to said first plate and with said first plurality of grooves in the first plate disposed in alignment with the second plurality of grooves in the second plate to provide a plurality of waveguide regions. The waveguide regions are further disposed to provide a plurality of hybrid Ts preferably matched hybrid Ts or magic Ts which are selectively interconnected to form an integrated combiner structure. A first surface of the plate is used to mount a plurality of IMPATT diode modules whereas the second opposite surface of the composite plate is used to mount a heat sink thereby providing a thermal path between the diode modules through the composite plates to the heat sink.

Abstract: An elastomer support for a sonar transducer includes a ceramic stack electromechanical driver, a pair of rigid support members, and a pair of elastomer layers disposed between the ceramic stack electromechanical driver and the support members. The elastomer support provides effective mechanical stress reduction in the ceramic stack driver, as well as, a simple, reliable heat dissipation means for the transducer.

Abstract: A transmit/receive (T/R) module of an electrically steered phased array antenna having a receiver comprising a T/R switch, an impedance matching and bias feed network, and a low noise amplifier. The T/R switch comprises a .pi. network to provide a matched termination for protecting the receiver in the transmit mode. This .pi. network emulates a one-eighth wavelength transmission line by providing a 45 degree phase delay, but it exhibits the isolation and bandwidth characteristics of a one-quarter wavelength line. The T/R switch effectively isolates the low noise amplifier from an antenna during transmit mode and uses less than half the area on a substrate typically required for a conventional one-quarter wavelength transmission line. In a receive mode the T/R switch has minimal effect on an RF input signal passing through it.

Abstract: An apparatus for processing a stream of digital data to provide a set of linear prediction coefficients and prediction error sequence representing said block of data which, when used to reconstruct the block of data, will reconstruct the data with a minimum distortion level is described.

Abstract: Method and apparatus for bending metal tubes such as for furnace heat exchangers. After the bend die is rotated 180.degree. to make a bend, an upper section of the bend die is split from a lower section, and the upper section is then rotated approximately 90.degree.. In such manner, a portion of the upper section is displaced laterally to vacate a region directly above the lower section. Therefore, in moving the tube forwardly to a new location for a subsequent bend operation, a portion of a previous bend passes through the vacated region thereby enabling sequential bend angles that are less restricted than without rotating the upper section of the split die.

Abstract: A technique for increasing the strength of long wavelength infrared material, such as zinc sulfide and zinc selenide includes diffusing species which are applied to the materials as thin films into the zinc sulfide and zinc selenide material. Portions of the thin film material are thermally diffused to substantial depths of up to 100 microns below the depth of flaws formed in the body using one of two diffusion techniques. One diffusion technique uses hot isostatic pressure and the other uses a heat treatment carried out at or near ambient pressure in an inert atmosphere, such as argon or other suitable inert gas.

Abstract: A target tracking radar receiver for use in a semiactive tracking system wherein elevation angle data, azimuth angle data and Doppler frequency shift data are processed in a manner which enables narrow band filtering of target angle tracking data in the first intermediate frequency stage. The receiver is arranged to track, simultaneously, variations of target Doppler frequency and of transmitter frequency to permit the desired early narrow band filtering of the received angle data.

Abstract: A cathode of a crossed field device includes a first electrode and a second electrode disposed about and dielectrically spaced from the first electrode. In a preferred embodiment the electrode comprises a pair of electrodes, a first one of the pair being a masking electrode disposed about and dielectrically spaced from the first electrode and a second one of the pair being an emitter electrode disposed about and dielectrically spaced from the masking electrode.

Abstract: Method and apparatus for removing radon decay products wherein a fan directs air through a conductive cylinder that is grounded. Positioned axially within the cylinder is one or more cylindrical brushes, each having a shaft and radially extending conductive bristles with distal ends spaced from the cylinder. The shaft is connected to the fan so that the bristles rotate. Also, a static electric potential is applied to the bristles. The relative motion of the air and bristles is particularly effective at enhancing molecular diffusion to cause small unattached radon decay products to plate out on the bristles. In contrast, the electrostatic charging of the bristles and the resulting diffusion charging is particularly effective at exerting a force on larger particles to which radon decay products are attached thus causing the particles to migrate and plate out on the cylinder.

Abstract: A low array antenna having transmit/receive (T/R) modules, which contain a digitally-controlled variable attenuator, for each of the two polarizations (horizontal and vertical). The array has a cylindrically curved surface which closely conforms to the shape of the fuselage of an airborne vehicle or another structure. Each polarization feeds into an elevation beamformer apparatus which provides both a uniform taper and a Bayliss/Taylor taper. As the beam is scanned in elevation, the amplitude taper is adjusted via the variable attenuator to control the taper of a sum pattern and thereby achieve low sidelobe far field sum patterns. The same attenuators that are used for the sum pattern also feed a difference network. The T/R module attenuators are set to yield the desired low sidelobe sum illumination for a desired elevation scan angle.

Abstract: A circuit for compensating for GaAs FET amplifier gain variations over a frequency band as a function of temperature. The circuit includes a passive equalizer circuit having a fixed gain over the frequency band and an active equalizer circuit having a gain which varies over the frequency band as a function of temperature. The passive and active equalizers are coupled in series. The active equalizer circuit comprises varactor diodes in a low pass filter arrangement with the bias voltage of the varactor being provided by an external driver controlled by a temperature sensitive thermistor. As the value of the varactor's junction capacitance is increased (as a function of the temperature controlled bias voltage), the cutoff frequency of the low pass filter decreases.