Abstract: The target simulation system includes a reflector 18 located within a closed and shielded room 10. An array 30 of transmitting elements is located within an opening 22 of the room so that the array is centered at a first focal point F.sub.1 of an ellipsoidal reflecting surface 18A of the reflector, and a receiving element of the target seeker 34 to be tested is located within an opening 24 so that the receiving element is centered at a second focal point F.sub.2 of the ellipsoidal reflecting surface. Phased array control system 32 causes the array to simultaneously and independently transmit a plurality of beams of radiation toward the reflector and each transmitted beam results in a corresponding reflected beam whose beam axis passes through the second focal point of the array so that each reflected beam simulates radiation coming from a distinct target. In the case where the radiation is electromagnetic radiation in the MMW range, the phased array control system (FIGS.

Abstract: The aftermath of a nuclear explosion generates a large amount of heat or infrared energy. When this heat is received by a parabolic reflector type antenna, the level of heat concentrated on the focal area of the feed is very intense. The present invention utilizes a highly heat conductive ceramic plug between the splash plate at the focal area of the feed and the waveguide so that heat can be readily conducted away from the splash plate and thereby minimize operational destruction of this splash plate due to thermal overload. The heat conductor material is a ceramic which is substantially transparent to RF signals being received by, or transmitted from the waveguide of the antenna system.

Abstract: A radar system alternately transmits relatively short and long pulses. The video signals corresponding to the target returns from consecutive pulse transmissions are converted to digital format and then integrated except that radar return signals from targets within a first range resulting from long pulse transmissions are not used for integration.

Abstract: In combination: a geophone having a resonant frequency in the pressure wave band and a response that decreases with frequency below the resonant frequency; an amplifier connected to the geophone and having a gain which is substantially constant for frequencies above the resonant frequency, and which varies inversely with frequency for frequencies below the resonant frequency; a band-pass filter connected to the amplifier; a single channel rectifier connected to the band-pass filter; apparatus connected to the rectifier for obtaining short term and long term averages of the rectifier output; and apparatus including a comparator connectied to the last named apparatus for giving an output when the short term average exceeds the long term average by more than a predetermined amount.

Abstract: An active millimeter wave simulator for missile seeker evaluations wherein a missile seeker generates seeker signals and transmits them in the direction of an array of active antenna elements. Range timing signals are delayed in a time delay circuit to simulate a range between the missile seeker and a target. The seeker signals as received by the active antenna elements are supplied to a millimeter wave spectrum analyzer for determination of their frequency. A computer receives the determined frequency and controls a millimeter wave source to generate simulated target response signals with that same frequency but delayed in accordance with the time delay signal. The computer controls a master target control circuit to select a triad of antennas in the antenna array and to generate a phase center in the triad generating the target response signals. The millimeter wave spectrum analyzer further determines the frequency of the target response signals.

Abstract: A method for preventing a radar beacon's response to received pulses from a vessel which originate from the side lobes of the vessel antenna. The carrier frequency of the radar signal pulses to and received by the beacon is measured and a value of this frequency is stored when the amplitudes of the signal pulses exceed a certain high threshold level (Th). If signals after that are received which exceed a low threshold level (Tl) (but not the high) the carrier frequency of such signals is measured and a corresponding value is stored. Measuring two subsequent and equal carrier frequencies is considered as a criterion that a response signal from the beacon responding to the second received signal should not be transmitted. An arrangement to carry out the method is described.

Abstract: Disclosed herein is a radar jammer which utilizes an electronically agile, sparsely populated, phase controlled antenna array of pseudo-randomly spaced radiating elements to form a high gain, single narrow beam of radiation directed at a detected threat radar, but containing only a small fraction of the available transmitting power, while providing simultaneously therewith effective jamming radiation over a wide coverage region. Preferably, the plurality of radiating elements are sparsely disposed pseudo-randomly over an area surface to form an antenna array, the number of radiating elements in the array being less than the value of the surface area divided by the transmitting carrier wavelength (.lambda.) squared.

Abstract: Cathode ray tube drive circuitry in which non-linearity of the line scan is corrected by varying the frequency of the pel clock oscillator in accordance with anticipated variations in scanning speed. Predetermined speed corrections are stored in a digital store 23 and, by means of digital to analog converter 24 and integrator 25, are applied to the control input of a voltage controlled oscillator 13. Synchronization of the pel clock with the X-deflection waveform is effected by means of a parallel phase-locked loop comprising counter 15, sample and hold 18, amplifier 20 and low pass filter 21. Preferably a sinusoidal waveform is applied to the X-deflection coil in such a manner as to have a bidirectional raster scan, the X-deflection coil forming part of a tuned circuit of the sinusoidal waveform generator.

Abstract: A solid propellant gas generator operating with a calibrated tunable resonator produces a strong sonic field capable of affecting particle coagulation in an aerosol. The resonator is calibrated to produce a sonic field at the optimum frequency for a given aerosol and can be changed according to the aerosol involved. The resultant coagulation increases visibility and/or electromagnetic transmissibility within the sonic field. The device can be used to reduce obscuration during battlefield operations.

Abstract: An apparatus for control of ground clutter breakthrough in MTI radar which remove hard limited clutter signals while allowing increased detection sensitivity to moving targets when such strong clutter returns are not present. Logic is provided to prevent the removal of strong moving target return even in the presence of hard limited clutter.

Abstract: Clutter suppressors and methods of clutter suppression for radars which employ the doppler effect for enhancing signals due to moving targets relative to signals due to clutter caused land, sea or rain. Specifically, the disclosure concerns suppressors and methods of clutter suppression for cw doppler, pulse doppler and MTI (moving target indication) radars. The suppressors reduce the occurrence of radar output due to clutter by permitting and prohibiting radar output on the basis of the relative strength of signals that contain doppler frequency components of the radar echo.

Abstract: An apparatus for use in evaluating the effectiveness of an ECM technique, such as the Cross Eye technique, which transmits RF signals from spatially separated antennas against a hostile radar system, such as a monopulse radar. The invention splits the radar transmit RF signal into separate paths, applies the ECM signal, and calibrates the combined radar-ECM signal for phase and amplitude balance after every pulse repitition interval. The signal is down converted to an intermediate frequency where a radar receive antenna is simulated. Following the antenna, an injection network up converts the frequency of the signal and adds computer controlled inputs (including echoes) prior to sending it to the radar receiver for final processing.

Abstract: An apparatus is disclosed by which radar targets can be imaged in two dimions for identification at full radar range using relatively moderate speed data processing. Images of targets are found in range and cross-range dimensions from the time history of the targets' wideband spectral response obtained by a frequency stepping radar. A frequency synthesizer generates a series of N identical signal bursts, each burst comprising n pulses and each of said n pulses being a different frequency. The radar echos from this series of bursts is separated into n-phase and quadrature phase components. These components are processed to calculate and store the relative amplitude of each echo signal and to determine the phase of each echo signal relative to the phase of the corresponding transmitted pulse. Further, the echo signals are inverse Fourier Transformed to generate an n.times.N Fourier Transform array representing a synthetic target range profile.

Abstract: A pulse width and amplitude control apparatus wherein an analog Doppler to digital pulse converter provides pulses to the up input of an up/down counter in the presence of a noise input or a Doppler input, and a second analog Doppler to digital pulse converter applies pulses with greater frequency to the down input of the up/down counter when a Doppler signal exceeding a predetermined threshold is present, so that a low or no signal condition increases and a high signal condition decreases the transmit pulse envelope.

Abstract: A distributive beam steering computer network for a radar phased array antenna is disclosed which provides direct drive for individual antenna phase shifter elements using a plurality of microcomputers co-located with each phase shifter. The microcomputers calculate the phase shift based on constants stored in a ROM which is located in each microcomputer and phase shift data comprising sin .alpha., sin .beta., and 1/.lambda. signals are distributed to all microcomputers over a single serial data line. The constants required for each shifter are different, and therefore, the ROM in each microcomputer is programmed for a specific location in an array antenna. A phase shift steering command for each element of the phased array antenna is calculated using a shift-and-add multiplication algorithm which is hard-wired into each microcomputer.

Abstract: Doppler radar for measuring objects, including a first and a second substantially prismatic cavity resonator each having an end facing the object to be measured and each having substantially equal dimensions, a common wall connecting the cavity resonators to each other, an oscillator diode disposed in the first cavity resonator, a receiving diode disposed in the second cavity resonator, the end of the first cavity resonator facing the object to be measured being closed and the end of the second cavity resonator facing the object to be measured being open, and the common connecting wall having an opening formed therein.

Abstract: A spread spectrum radar apparatus wherein a plurality of carrier signals frequency modulated over predetermined time intervals and separated in frequency such that the spectra of the signals do not overlap are sequentially transmitted. Radar returns of this transmission sequence are coupled to a receiver which is frequency band activated in accordance with the transmission sequence and in a manner to minimize radar minimum detection range. Each radar echo is processed through a matched filter for pulse compression, delayed in accordance with the position of its transmitted signal, detected, and non-coherently summed with detections of returns from the same target of other interval transmissions.

Abstract: A range finder for measuring the distance of an object to be measured by the steps of radiating the spot light to the object, forming an image of the reflected ray of light by image forming means and measuring the distance of the object from the output of an element which is disposed at a position substantially corresponding to the image forming position and of which output varies in accordance with the light-receiving position on the light-receiving surface. PSD are used as the element. A focussing detector which includes a semiconductor position detection element PSD placed at a position corresponding to the film surface in a camera or the like and detects the focussing state on the basis of the electric output from the semiconductor position detection element PSD.

Abstract: The DME pulse pair is followed by a third, steep-edge pulse. The time marks are divided from the third pulse. To ensure that no random pulses are evaluated as the third pulse, the pulse pairs are still evaluated for decoding and to control tracking, while the third pulse can be evaluated only during a given time after the reception of the pulse pair. The novel interrogators and transponders can also cooperate with existing interrogators and transponders, in which case only the improvement in accuracy is lost.

Abstract: A radio altimeter of the FM/CW type which is linearly frequency modulated by a triangular wave exhibits step error in the output indication at times near the peaks of the modulating wave. Step error is eliminated by gating the data which is processed to produce the altimeter output indication to inhibit processing during times the modulation wave is near peak values and to enable processing at other times. Accuracy is further improved by adjusting the duration of the time during which data processing is enabled so as to equal an integral number of cycles of processed data.