Abstract: A step attenuator comprises two branchline couplers with two coupling transmission lines therebetween. Attenuation is accomplished through switchable resistors, in series with switching diodes, shunted across the transmission lines. These resistors reflect and absorb incident power. Switching signals are provided to the diodes through the branchline couplers and the coupling transmission lines. The reflected power is absorbed by a matched termination at the port of the input branchline coupler that is isolated from the port at which the signal to be attenuated is coupled. Phase shift and insertion loss are minimized by tuning the series inductance inherent in the diode resistor combination with tuning capacitors in series therewith. These capacitors are by passed by low-susceptance inductors which provide a dc path to ground for the diodes.

Abstract: An estimator for determining the distance of a moving vehicle to a stationary position includes the determination of actual and estimated velocities of the vehicle along a selected path. An up-dated distance estimate is established by multiplying estimated distance by the ratio of the actual velocity to the estimated velocity. The up-dated estimate is then utilized as the estimated and another up-dated distance is obtained. Iterations continue until the ratio approaches unity indicating that the estimated distance is approximately equal to the actual distance.

Abstract: A surveillance sensor for detecting and monitoring aerodynamic conditions in a vicinity of an aircraft landing glide slope utilizes a radar transmitter to illuminate the glide slope. Radar reflections from aircraft induced vortices, clear air turbulence, and glide slope cross winds are received by a monopulse radar system wherein a sum beam doppler spectrum and a difference beam doppler spectrum for the radar returns is determined. The sum and difference beams doppler spectra are processed to determine the aerodynamic conditions in the glide slope vicinity. These aerodynamic conditions are assessed to determine whether aerodynamic hazardous conditions exist in the glide slope region.

Abstract: An instrument storage tray is provided that is compartmentalized for the storage of instruments of various sizes and for the storage of instruments of given configurations. The tray has slots at the wall junctions and legs extending from the wall junctions configured for insertion of the legs of one tray in to the slots of another tray so that a plurality of trays may be transported at one time.

Abstract: The line of sight of an airborne radar antenna is stabilized from the pitch and roll motions of the aircraft by mounting the antenna on a three degree of freedom gimbal system. The gimbal system is comprised of a first gimbal mounted for rotation about the aircraft Z axis (azimuth) for pointing the antenna along the intended line of sight, a second gimbal mounted on the first gimbal for rotating up and down with respect to the azimuth gimbal and a third gimbal mounted on the second gimbal to which the antenna is connected for providing rotation to align antenna polarization relative to inertial ground. A two degree of freedom stabilization gyro provides stabilizing signals representative of aircraft pitch and roll motions with respect to inertial reference axes.

Abstract: A weather surveillance apparatus utilizes a set of beams in an elevation angular sector, one beam being offset from the other by a predetermined offset angle. Radar signal returns in each beam are processed to establish an average doppler frequency shift for the signals in the respective beams. An average of the averages and a difference of the averages are determined which are utilized to establish horizontal and vertical wind velocities. These velocities are further processed to determine whether a microburst precursor exists and the location, magnitude, time to impact, and track of any resulting windshear.

Abstract: Range gate delay is effected by serially connected coarse and fine programmable delay lines. The radar transmit trigger pulse is propagated through the programmable delay lines to provide a delayed trigger pulse. The delayed trigger pulse triggers a range gate generator for generating the range gate. The delay effected by the coarse and fine programmable delay lines is controlled from the system CPU. The range gate generator comprises a D-type flip-flop with the Q output thereof connected as the input to a further programmable delay line. The delayed trigger pulse sets the flip-flop and the output of the further programmable delay line resets the flip-flop. The range gate is provided by the Q output of the flip-flop. The width of the range gate is determined by the delay set into the further programmable delay line by the system CPU.

Abstract: The coupler includes a waist region formed by merging and fusing a plurality of optical fibers with the waist region encapsulated in photorefractive encapsulating material. The index of refraction of the encapsulating material is modulated by applying illumination thereto, so as to vary the coupler output ratio. The applied illumination can direct the coupler output from one output fiber to another output fiber thereby providing an optically actuated switch. The illumination applied to the encapsulating material can direct a large optical power signal applied to an input fiber from one output fiber to another output fiber thereby providing an optical amplifier analogous to a transistor. One of the output fibers of the element can be utilized to provide the encapsulating material illumination thereby providing an optical feedback oscillator.

Abstract: A net for capturing and observing objects includes a pouch of netting material, spring arms which support the pouch and automatically opens an aperture, through which the object may pass for capture, when released from a slot in a mechanism which supports the spring and net. A telescoping handle coupled to the support mechanism adjusts the distance at which objects may be captured.

Abstract: A microburst precursor detector utilizes a multiplicity of radar beams and samples radar returns, in each beam, from meterological radar signal reflectors and processes the signal returns in a statistical manner to determine average radar reflectivity and to extract doppler signal parameters. These parameters are utilized to determine a second set of parameters; average doppler frequency within each radar beam, doppler spectral spread within each radar beam, and the skewness of the doppler spectrum in each beam. The second set of parameters is processed to establish the existence of a microburst, predicted surface impact, time to impact, wind shear surface location and track, and the magnitude of the wind shear.

Abstract: A submarine radar antenna mast extension, retraction and rotation mechanism comprises a ball drive screw attached to the mast with a ball drive nut threaded to the screw. A rotary tube surrounds the mast with the mast keyed for translation within the rotary tube and prevented from rotation with respect to the rotary tube. An outer tube surrounds the rotary tube and effects a static hull penetration seal with respect to the submarine. The rotary tube rotates within the outer tube, but is prevented from translation with respect thereto. A brake/indexing assembly geared to the rotary tube selectively releases the rotary tube for rotation or locks the rotary tube to an indexed position for extension and retraction. A single bi-directional hydraulic drive motor geared to the ball drive nut effects mast extension and retraction by applying the brake to prevent rotary tube rotation. The drive motor effects mast rotation by releasing the brake.

Abstract: An autocoupler flange is coupled to a rigid waveguide through a flexible waveguide. The autocoupler flange is supported in a stationary housing by support pins projecting through shaped apertures in the housing and a system of springs to maintain the autocoupler flange in a position skewed to the vertical. The autocoupler flange includes a stop member with a horizontal alignment slot therein. A movable waveguide flange has an alignment bracket secured thereto, the alignment bracket including a horizontal alignment pin. Vertical motion of the movable waveguide flange and alignment bracket engages the autocoupler flange, lifting the autocoupler flange from its support on the stationary housing. The horizontal alignment pin engages the horizontal alignment slot to provide horizontal alignment between the flanges. In the coupled position, the autocoupler flange is supported on the waveguide flange with the system of springs locking the flanges together.

Abstract: A digital underwater communication system includes a transmitter and a receiver. An oscillator bank in the transmitter generates a plurality of signals, each having a unique frequency. A timed switching matrix selects predetermined combinations of signals from this plurality and a gate passes only those signals within a selected combination that corresponds to the binary value of a bit to be transmitted. A timer commands the switching matrix to select different combinations at each bit time. The receiver contains a filter bank feeding a plurality of channels, each responsive to a different one of a plurality of signals generated in the oscillator bank. A receiver timer, synchronized with the transmitter timer, enables combinations of receiving channels corresponding to the combinations of signals selected by the transmitter switching matrix during that bit time.

Abstract: A path capture forcing function generator utilizes integrations from an initial altitude rate error signal and an initial altitude error signal to provide an altitude rate signal and an altitude signal which are compared to the altitude rate error and altitude error signals to provide path rate error and path error signals to the autopilot. In the process of providing the altitude rate and altitude error signals an altitude acceleration signal is established which is used as a feed forward predictor for expected normal acceleration of the aircraft.

Abstract: A precision variable attenuator includes quadrature hybrid circuits, each having a first pair of isolated ports corresponding to the input and output ports of the attenuator. The second pair of isolated ports each are terminated with variable impedances in a manner to provide equal reflection coefficients at each port. Signals incident to the input port are coupled to the second pair of isolated ports and reflected therefrom to be coupled to the output port.

Abstract: A ship steering system has a multiplicity of selectable steering stations. A continuously rotating helm at each steering station generates digital rudder control signals which cause a predetermined rudder movement for each 360.degree. of helm rotation. Steering stations are selected through a multiplexer controlled at a command steering station. The steering system is operable from the command steering station in a plurality of modes, which includes auto-pilot, helm (full-follow-up), and tiller (non-follow-up). Helm and/or tiller modes of operation are available at steering stations remote from the command steering station. The system provides for an emergency takeover from the helm or autopilot modes by automatically establishing the tiller mode when the tiller stick is moved. When in the autopilot mode an alarm system provides an alert should the course deviate from a selected course tolerance.

Abstract: An MOS FET pass element for a switching voltage regulator is driven by a dual voltage booster configuration. The pulse width modulator of the regulator provides a two-phase logic signal for alternately energizing and charging each booster. Each booster is comprised of a capacitor charged from a charging voltage source and coupled to the gate of the FET for providing a turn-on voltage thereto. A switching transistor associated with each booster alternately couples the associated booster capacitor to a predetermined voltage and to ground. The capacitors alternately provide the turn-on voltage to the FET when the predetermined voltage is applied thereto. On alternate half cycles, each capacitor is charged from the charging voltage source. The two-phase logic signal alternately renders the switching transistors conductive. A NAND gate responsive to the two-phase logic signal, permits the FET to be turned on by the voltage boosters only during the presence of each of the logic signals.

Abstract: A system wherein TCAS transmissions have two jitter components added to the jitter component utilized in the interscan interval to minimize TCAS interference with ground station operation. The jitter components minimize the establishment of false intruder tracks caused by responses to ground station interrogations or interrogations by other TCAS interrogators which are received in synchronism with the TCAS interrogation signals.

Abstract: Cardiovascular sounds from a patient's body are monitored by placing a fiber optic coupler sensor at an appropriate location on the patient to sense the sounds. The sensor is comprised of all dielectric material having a variable coupler waist region encapsulated in material with index of refraction that varies with applied stress. Stress is induced in the encapsulating material in response to the cardiovascular sounds. Sensor configurations include encapsulating material membranes with curved surfaces to enhance sensitivity.

Abstract: The vector generator employs a digital accumulator for each vector component. The accuracy of generated vectors is optimized by presetting the fractional portions of the accumulators to a value of either 1/2 or to 1/2 less 1 LSB. Accumulation of errors over concatenated vectors is eliminated by employing high enough fractional resolution relative to the maximum vector length so that error accumulation on any single vector is limited to the fractional portions of the accumulators, and by setting the fractional portions of the accumulators, on the last clock cycle of each vector, to a value of 1/2 to 1/2 less 1 LSB. Also, by setting/presetting the fractions to only 1/2 less 1 LSB, and by enabling the carry input to a given accumulator on only the first clock cycle of vectors that have certain orientations, then symmetry is forced or favored in complex symbology that is generated by concatenated vectors.