Abstract: A system for Doppler frequency measurement, responsive to spectral modulation induced by a reverberant and nonlinear radiation transmissive region such as the ocean, and composed of a Fourier transformer for providing digitally the spectral lines for a set of samples of a Doppler signal, a circuit for obtaining the logarithm of the power spectrum, weighting of the logarithm by othogonal functions, and an arithmetic combination of components of the weighted logarithm.

Abstract: A radiographic camera of the form employing a scintillator for producing optical photons in response to incident gamma and X-radiation, a collimator positioned between a subject emitting such radiation and the scintillator for guiding the radiation to the scintillator, and a detector of optical photons for signaling the positions of points of impingement of quanta of the incident radiation upon the scintillator to produce an image of the subject, the improvement being a Fresnel focussing means located alongside the scintillator for directing the optical photons to the detector. The Fresnel focussing means takes the form of a segmented mirror at the front surface of the scintillator and a Fresnel lens at the back surface of the scintillator.

Abstract: A radar system with digitized video having a digital interference rejection circuit for eliminating spiral interference caused by nearby radar transmitters operating in the same frequency band. Video signals from each sweep are stored in a random access memory. A comparison is made between adjacent range cells in the present "live" video signal and the video signal from the previous sweep. The output video signal to the display device is inhibited should the comparison indicate the presence of interference.

Abstract: A recorder in which a stylus is transported in successive line scans across a recording medium for imprinting data thereon, a stylus transport having a guide edge with which the stylus makes sliding contact, the stylus transport having a lubricating surface against which the stylus is guided for producing a thin film of lubricant upon the stylus. The lubricating film prevents wear between the stylus and the guide.

Abstract: A radar system having an adaptive compass drive capable of operation over a wide variety of compass outputs and supply voltages and frequencies. For compass outputs in the form of multi-phased analog signals, a digital phase detector converts the signals to a series of digital pulses which are used to operate a three-phase to UP-DOWN pulse converter. If the gyro compass output signals are in the form of overlapping digital signals, the converter changes the signals directly to a sequence of UP or DOWN pulses. The UP-DOWN pulses are used to operate a binary counter which operates the phases of a multi-phased stepper motor which is coupled to the true bearing scale of the radar system the output of which may also be used to operate a north stabilization synchro converter for the radar display.

Abstract: A radar system having transmitted and received signals, the system including a feedback loop for modulating a sample of the transmitted signal to duplicate the phase and amplitude of the clutter echoes from nearby points of reflection. The modulated transmitted sample is subtracted from the received signal to remove the clutter. The feedback loop detects differences between the clutter-free signal and the transmitted sample to produce an error signal, the error signal being filtered and applied to the modulator for modulating the phase and amplitude of the transmitted sample.BACKGROUND OF THE INVENTIONThis invention relates to echo ranging systems such as radar and sonar systems and, more particularly, to an echo ranging system in which clutter returns from nearby objects are removed from echoes from distant objects.

Abstract: A cylindrical array of radiating elements or sonar transducers each of which is coupled by a clipping circuit to a multiply tapped shift register for imparting delays to the signals of the elements for forming a beam of radiant energy. Sidelobes on the radiation pattern are reduced by multiplying the signals of the shift registers by weighting factors prior to their summation for forming a beam, clipped signals serving as unitary factors of positive or negative sign in the multiplication.

Abstract: A recorder in which a stylus assembly is transported across a recording medium at increased speeds by a flexible non-extensible belt having its edges slidably nested within slots oriented transversely of the recording medium. The belt has molded teeth for accurate mating with a sprocket drive.

Abstract: A Read-type avalanche diode having a low noise measure and capable of attaining output signal powers of one watt or more. An effective injection current is defined as the conduction current in the avalanche zone in the absence of avalanche multiplication including therein any tunneling current. The noise measure of the diode is minimized by increasing the defined effective injection current with disclosed techniques. In one embodiment, the effective injection current is increased by the presence of traps located in the avalanche region. In another embodiment, a Schottky barrier contact having a low work function is provided. Surface states of the avalanche region are also varied to produce the desired increase. Increased effective injection current may also be produced in a device with preferred heat flow properties. The noise performance of both oscillator and amplifier circuits is improved with the invention.

Abstract: A radar system having the radar pulse rate controlled directly from an indicator unit. Separate modulator-transmitter-receiver and digital video processor indicator units are provided. A radar trigger pulse is produced by the processor unit in synchronism with the processor clock at a rate determined by the radar range setting. An acknowledge signal is produced in turn by the modulator-transmitter-receiver in accordance with an activating signal in the modulator and fed back to the indicator unit to start video signal digitization and the CRT sweep. Jitter between the start of the radar return signal and the radar sweep are eliminated.

Abstract: A gamma camera with a plurality of photodetectors arranged for locating flashes of light produced by a scintillator in response to incident radiation. Masking material is arranged in a radially symmetric pattern on the front face of the scintillator about the axis of each photodetector to reduce the amount of internal reflection of optical photons induced by gamma ray photons.

Abstract: A display system having a cathode ray tube signal generator in which a solid state junction target utilizes a layer of semiconductor material and a layer of dielectric material to form a junction. The signal generator may be of the monoscope type in which portions of the target are masked or it may be of the photosensitive type in which an image is projected onto the target. A signal derived from the signal generator is displayed on a second cathode ray tube.

Abstract: A ranging system, particularly useful for sonic depth sounding employing a receiver utilizing one bit sampling of received echoes. A correlator correlates a sequence of one bit samples against a sequence of reference samples, such a sequence of reference samples being conveniently provided by a transmitter of sound waves. An envelope detector circuit provides the envelope of received echoes and a peak detector provides the time of occurrence of the peak of the envelope. A gate generator responsive to the time of occurrence of the envelope peak provides a gate signal which brackets a succession of output pulse signals from the correlator to delineate coarse range or depth while individual output pulses within the gated interval are applied to a second peak detector to give a range or a depth reading corresponding to the time of occurrence of the maximum output pulse of the correlator.

Abstract: A method of making a number of semiconductor diodes on a single wafer without breakage during handling and processing, comprising the steps of forming a plurality of mesas on one surface of an intrinsic substrate, diffusing a selected first conductivity-type region into each mesa, coating the front surface of the substrate and mesas wiyth oxide, chemically milling recesses into the opposite side of the substrate in alignment with the mesas to a predetermined depth where the mesas are each supported by a thin annular area of substrate material permitting transfer of the device into an epitaxial reactor, gas etching the recesses to a depth beyond the oxide interface to physically separate the mesas from the substrate material, growing a thin epitaxial layer of opposite conductivity type over the back surface of the device, applying ohmic contacts to the device, and separating the individual mesas.

Abstract: A data sample recording system having a memory for storing a predetermined number of data samples accumulated over various intervals of time. Each interval of time is divided into a predetermined number of subintervals, there being an electrical circuit for detecting the peak value of data occurring in each of the subintervals. The occurrences of the subintervals are synchronized with a periodic passing of a stylus across a recording medium in a recorder. The predetermined number of data samples is equal to the number of resolution elements of a line of data on the recording medium, stored data being fed out to the recorder in synchronism with the stylus movement to provide a display of data having a predetermined number of resolution elements of display independent of the length of the interval of time.

Abstract: A tracking system for use with an antenna having a multiple beam radiation pattern for sensing the direction of radiant energy incident upon the antenna. Pairs of the beams are selectively coupled to a monopulse comparator comprising a pair of hybrid couplers interconnected by a fixed phase shifter providing 90.degree. phase shift and by a pair of variable phase shifters providing phase shifts of equal magnitude but opposite sign. The output of the second hybrid coupler provides monopulse sum and difference signals. A sensing circuit responsive to the sum and difference signals operates the variable phase shifters to steer a null between the selected pair of beams.

Abstract: A method of energizing a laser source stimulating flash lamp directly from an AC power line. Uncontrolled diodes couple the anode and cathode of the flash lamp directly to the AC line. The lamp is triggered by a separate triggering circuit which produces its trigger pulse at a predetermined phase of the AC power source. The use of high current carrying controlled rectifiers and large energy storage devices is thereby eliminated.

Abstract: A transducer assembly in which a transducer unit of a piezoelectric material which is rigidly held between a rear member and a front member, both of which are made to vibrate upon energizing the piezoelectric material. Inductive elements comprising copper conductors wound about iron cores and utilized in the tuning of the transducer assembly are rigidly connected to one or both of the members and may also be connected to the transducer unit itself to serve as a portion of the inertial mass which imparts a mechanical vibrational characteristic to the transducer assembly. In one embodiment of the invention, the rear member is provided with a void wherein there is nested an inductor having an inertia similar to that of the material removed from the rear member in forming the void.

Abstract: A temperature compensated acoustic surface wave device, such as a surface wave delay line is provided in which temperature compensation is provided by the deposition of an interdigital electrode structure on a substrate with an overlay film surface of piezoelectric material of a predetermined thickness. A double substrate arrangement is also disclosed in which the interdigital electrode structure is deposited upon the surface of a non-piezoelectric layer which in turn is placed upon the surface of a piezoelectric substrate.

Abstract: A preregulator power supply having drive and control circuits which are isolated or floating alternately from the input and output leads to permit direct coupling to the power switching regulator device without requiring isolation devices such as transformers or optical isolators. This is achieved by an added series winding on the output choke, the common junction of which is connected to the output of the switching regulator and also forms the return lead for the floating drive and control circuits, while the added winding provides a sample output voltage for comparison by the floating drive and control circuits to control the width of pulses fed to the switching regulator device. A free-wheeling diode is also connected from the output of the switching regulator to an output terminal to maintain current in the choke during the OFF cycle of the switching regulator and provide several isolated regulated voltages in windings magnetically coupled to the choke.