Abstract: A pulse radar for acquiring a target while rejecting the altitude line is described wherein a plurality of target reports from a scanning antenna are examined and rejected if the pattern of target reports at an apparent range extends along a scanning angle too large to be a valid target and selected if the pattern of target reports at a range extends along a limited scanning angle indicative of a target having a valid target size. Target reports rejected during a prior scan may be used as a basis for rejecting target reports of a current scan.

Abstract: The tuned elements of a mixer organization are fabricated as slot-type microwave integrated circuit (MIC) elements formed by selected masking or etching of a continuous ground plane layer of conductor material on one side of an integrated circuit dielectric substrate, and of the discrete strips and other geometric forms affixed to the other side of the substrate. A pair of longitudinally aligned coplanar strip transmission line sections with an intermediate short longitudinally aligned slot transmission line section therebetween form hybrid junctions containing balanced diode modulation circuits where such coplanar lines and the slot line are joined. A strip line unit formed on the other side of the substrate is the input port for the RF input signal and is configured to provide a microstrip line-slot line transition at the midpoint of the slot line, feeding the RF input signal to both hybrid junctions with the same phase.

Abstract: A compact refrigeration unit supported by a generally rectilinear frame structure with front and back frame members having their axial planes spaced apart along the long axis of the frame is provided with a first selectively energized prime mover positioned within the frame with its relatively long rotary drive shaft in alignment with the long axis of the frame and a second selectively energized prime mover positioned within the frame with its relatively short rotary drive shaft extending from front to back frame member planes at right angles to the shaft of said first prime mover, there being clutch means to connect said first prime mover to a refrigerant compressor within said frame to drive said compressor when said first prime mover is energized and said clutch is engaged and there being right angle drive means including flexible connections to connect said compressor and said second prime mover to drive said compressor when said second prime mover is energized and said first prime mover is deenergized wi

Abstract: A method and apparatus for synchronization of a digital divider chain with a low frequency reference pulse train is embodied in the form of all digital circuit apparatus suitable for fabrication by state of the art high density packaging techniques such as Large Scale Integration (LSI) or Multi-chip Hybrid Packaging (MHP). Each individual substage of the divider chain is reset to its ZERO condition by a circuit including first and second flip-flops which receives inputs from the master oscillator clock driving the divider chain and from the source of the low frequency reference pulse train.

Abstract: A method and apparatus for controlling the diameter of single crystals grown by the Czochralski process in which an infrared sensor determines the temperatures of the melt adjacent to the crystal and a control circuit compares an average of these temperatures to a reference temperature to provide an error signal which controls the inductive heating of the melt.

Abstract: A diode switched microwave phase shifter network consists of a series of alternate path, phase increment stages. The diodes which control direction of current through the alternate paths are all commonly poled so that a single D.C. diode forward biased source applied between the ends of the network operates all the diodes. The alternate paths of each phase increment stage are controlled by the series connection therein of a collector-emitter internal circuit of a low frequency transistor.

Abstract: Improved low frequency electro-acoustic transducer apparatus of the type employing two piezoelectrically driven flexure discs mounted at the ends of a short cylindrical housing containing an acoustic mismatch fluid, is provided. The piezoelectrically driven flexure discs are constructed as assemblies having a plurality of concentric piezoelectric laminar sandwich units to excite the flexure discs. By individually electrically exciting the concentric sandwich structures through band-pass filters and a selective interconnection network, the flexure discs function with a plurality of resonant frequencies of flexing to provide broad band and efficient operation.

Abstract: A circuit for selectively variably setting the magnetic remanence in a magnetizable core employs flux circuit feedback, including feedback initiating a self-blocking oscillator type of operation, to achieve designs of two or three (as the designer may desire) elementary sequences (referred to in the art as cycles) to erase previous remanent flux density and to set a new remanent flux density. The circuit apparatus is amenable to constructions using single monolithic integrated circuit chip techniques.

Abstract: An FM/CW radar system which uses a single duplexed antenna, in which high degree of isolation of the transmission signal from the receiver is provided by passive power limiter devices employing the subsidiary resonance mode of narrow linewidth ferrite materials. In devices which are magnetically biased for operation in the subsidiary resonance mode, strong r.f. fields resonantly couple to spin waves, thus causing power absorption for signals at the frequency of incidence which exceed a predetermined threshold. A signal exceeding the threshold is attenuated over a narrow band at the frequency of incidence while the weak FM/CW target echo return signals are transmitted to the receiver with very low loss, provided their frequency displacement is of the order of 15 MHz from the frequency of incidence.

Abstract: A method and apparatus for determining the altitude of a transmitted signal by adding the altitude of the transmitting antenna to accumulated changes in altitude, determined in relation to the sine function of the elevation angle of the propagation path. The elevation angle of the propagation path is determined in relation to the elevation angle of the transmitting antenna and the local elevation angle change in the propagation path accumulated over the propagation range. The local elevation angle change in the propagation path is determined in relation to a dynamic, vertically dependent refractive index gradient model and in relation to a vertically dependent curvature model.

Abstract: Tracking apparatus which includes a plurality of trackers and a single track loop for tracking a plurality of radar threats or threat signals on a time-shared or time-multiplexed basis. The trackers cooperate with a receiver and a processor which processes the received threats deriving for each threat its carrier radio frequency or frequencies (RF) and its pulse-repetition interval or intervals (PRI), and determining the real time of arrival (TOA) of the pulses of each threat. All received threats in the trackers are scanned in succession periodically during scanning intervals. Each scanning interval is called a roll and each roll's duration (RO) is short compared to the PRI. During each scanning interval the TOA for the last-received pulse of each threat signal is compared with half the width of a window (W/2), neglecting the set-up time of the receiver.

Abstract: There is disclosed apparatus for, and a method of identifying radar signals from selected of their parameters, such as azimuth, instantaneous frequency, pulse duration and the like, so that countermeasures may be initiated. Since the signals are sensed from several radars and occur at short intervals of the order of one microsecond or less, and, for effective countermeasures, the radar systems must be identified in a very short time, instantaneous evaluation of the parameters is demanded. The signals are evaluated by a matrix including a pattern of adaptive memory elements, such as magnetic or solid state memory elements (minstors) disposed in columns and rows. A parameter is assigned to the adaptive elements in each column so that each row of adaptive elements corresponds to a set of parameters. The elements in each row are encoded with a different set of adaptations corresponding to the parameters which it is anticipated will match the parameters of the radar systems.

Abstract: A feed which is stationary relative to a parabolic reflector is located in close proximity to a prime focus of the reflector along its central axis. A moving element which is opaque to r.f. energy is moved along a path of revolution about the reflector axis, the path of revolution being located between the reflector and the stationary feed. The shape of the opaque element and the path of revolution are such that different portions of the aperture of the feed are masked as the element travels along the path of revolution. This imparts predictable scanning motion to the beam pattern which is coupled into the stationary feed. One highly useful embodiment of this invention is a construction in which the stationary feed is a secondary feed installed in a nutating feed antenna, and the nutating feed itself constitutes the opaque moving element.

Abstract: Method and apparatus for determining and applying a feedback current to the two sense windings of a vehicle mounted flux gate compass in order to provide a compensating magnetic field to cancel out the effect of local magnetic disturbance field(s) produced by the vehicle. Two zero crossing detectors for each channel respectively associated with the two sense windings indicate when the output from a sense winding passes through a null. This indication is used to enable a sample and hold circuit for the voltage on the opposite coil. During the calibration sequence the vehicle traverses a complete circular path wherein each coil passes through two nulls resulting in two voltages being sampled and held for each coil. The two pairs of voltages are then averaged, which then results in two resultant voltages which are representative of the lateral and longitudinal components with respect to the vehicle of the disturbance field.