Abstract: A glide slope indicator system in which light from an incoming aircraft's landing light is shaped by spherical/cylindrical lens combination into a line image which strikes a linear photodiode array. By determining which photodiode in the array the center of the line image strikes, the glide slope angle can be determined. An appropriate signal is communicated to the pilot via a pair of indicator lights mounted on the runway depending upon whether the aircraft is above, below or on the desired glide slope angle.

Abstract: The instantaneous frequency measurement (IFM) receiver is highly susceptible to erroneously reporting frequency if two or more signals are overlapped in time. This problem is extremely important when the receiver is presented with synchronized signals. A method is presented to detect simultaneous signals which overlap in the critical frequency encode strobe.In essence, during the pulse overlap condition, a transient will occur on the video output lines of the receiver. These lines are monitored during the transient period and compared with predetermined values which are obtained from the single signal condition. If a transient is detected, a simultaneous signal detect flag is raised and this flag is sent to an associated processor. In this special design, the receiver will measure the frequency again at approximately 200 ns from the first measurement. The transient detection is also performed on the second measurement.

Abstract: An FET complementary pair provides the output to a data line. A data input line is coupled to the gate of the P-FET via an OR gate configuration, and to the gate of the N-FET via an AND gate configuration. The output of each gate configuration is cross-connected to an input of the other. When the input data state changes, the two gate configurations provide delays which are effectively in tandem, so that the FET which was ON is first turned OFF, and after a short delay the other is turned ON. This delay ensures that both FET's are not ON at the same time, which prevents an undesirable power flow. To provide a high impedance "float" state, an enable input and its complement are connected to the AND and OR gate configurations respectively.

Abstract: The timer generates a selected number of control pulses per hour, at unpredictable (pseudo-random) intervals, for use with a time lapse video tape recorder used for time studies. The hour is divided into equal intervals to provide the number of samples required per hour, and one trigger pulse is generated randomly timed within each interval. A noise generator drives a counter whose outputs are loaded every Nth clock pulse into an N-stage shift register. The contents of the shift register are shifted out serially at the clock frequency.

Abstract: The IGFET is formed on a GaAs wafer which is coated with a layer of Si.sub.3 N.sub.4 and a SiO.sub.2 layer. The SiO.sub.2 is etched away in transistor areas, and ion implanting provides channel doping. A gate of refractory metal such as Mo is deposited and delineated. The gate and the SiO.sub.2 act as masks for ion implantation of the source and drain. The refractory metal gate allows subsequent annealing at high temperatures to activate the ion implanted species.

Abstract: A multiplexed data stream monitoring circuit comprises a random access memory for receiving and storing a multiplexed data stream which is transmitted together with a synchronization signal and a data clock. A counter circuit is reset by the synchronization signal and counts the data clock signals to accumulate counts uniquely identified with signals within the data stream which counts are used to address the random access memory. For each accumulated count within the counter circuit, the corresponding accumulated count location is addressed in the random access memory to read the immediately preceding state of the current signal within the multiplexed data stream. The current data stream signal and the immediately preceding data stream signal as read from the random access memory are compared by gating circuitry to identify characteristics of the data stream. State changes of the signals within the multiplexed data stream are identified if the gating circuitry comprises an EXCLUSIVE OR gate.

Abstract: An array of detector elements located at the focal plane of an antenna system can be used to reduce or eliminate the influence of glint induced tracking errors and increase the field-of-view of angle-of-arrival detection systems. The array at the focal plane is divided into four quadrants. Each quadrant has its own receive channel to detect the amplitude of the signals focused on that quadrant. The resulting amplitude signals are compared in pairs for diagonally opposite quadrants to develop two error signals (i.e., elevation and azimuth). This noncoherent detection is equivalent to an optical quadrant detector.

Abstract: A circuit for eliminating transient pulses generated by bouncing mechanical contacts within a switch. A shift register accepts a series of binary input signals from the switch and propagates the signal out the register in parallel to a logic device for generating a resultant binary signal corresponding to the switch's debounced signal state.

Abstract: An anode target comprises a copper block having different elemental target materials bonded to segments of the circumference, which rotate past the electron emitting cathode, to provide different emission lines in sequence. Aluminum and silicon target materials produce lines which bracket the aluminum absorption edge, to detect small amounts of aluminum in the presence of other absorbing materials by differential absorption of these two lines. Silver and rhodium may be used to bracket the chlorine absorption edge.

Abstract: Analog signals representing infrared radiation from an object are generated by a scanner. These signals are digitized and one frame of data is stored in a computer. The computer and a display generator process the data, and supply one frame to a TV monitor which displays an image of the object. A grey scale is also displayed alongside the image to provide calibrated quantitative information related to the temperature at different places of the object. A tape recorder may be used to record the analog signals, for later digitizing and displaying the images.

Abstract: An infrared sensor system for use on satellites comprising dual arrays of mercury cadmium telluride semiconductor elements. One array of conventional photovoltaic detectors is wired in parallel with a novel array of HdCdTe material in which the n-type region of each mesa and the resulting p-n junction is considerably smaller than that utilized in the conventional detector. As the cumulative dose of incident radiation is increased, type conversion in both arrays occurs resulting in degraded performance in the conventional array but an increase in performance caused by the now effective p-n junction area in the novel array. An electronic switching device, coupled with a dosimeter, alternately selects the conventional array or the novel array depending upon the total dose of radiation received.

Abstract: During installation or maintenance of a phased array antenna system in which the transmission line to each element includes an adjustable phase shift device, it is required that the effective electrical lengths of the lines be adjusted to be equal, or alternatively that the phase errors be determined and stored as correction data for use during normal operation. One way of doing this is to phase modulate by .+-.90.degree. the phase shift device of one element at a time, while applying a test signal to all elements. The signal is radiated by the array, received via a test antenna, and supplied to an envelope detector. If the element is out of tune, the envelope has different amplitudes at +90.degree. and -90.degree. of the modulation. The element is tuned by adjusting the length of its transmission line or the adjustment of its phase shift device to obtain a null at the amplitude detector.In an improved technique, to reduce certain errors, sum tuning is used, in which the .+-.90.degree.

Abstract: This invention involves measurement of the visual contrast sensitivity (modulation transfer) function of a human subject by means of a linear or circular spatial frequency pattern on a cathode ray tube whose contrast is automatically decreasing or increasing depending on the subject pressing or releasing a hand-switch button. The threshold of detection of the pattern modulation is found by the subject by adjusting the contrast to values which vary about the subject's threshold thereby determining the threshold and also providing by the magnitude of the contrast fluctuations between reversals some estimate of the variability of the subject's absolute threshold.

Abstract: An optical signal preprocessor for computing the input functions required to utilize an extended Kalman filter algorithm. An incoming stream of time-varying images is integrated to form a reference image, which is then subtracted from each subsequently sampled image. The result is digitized for use with the extended Kalman filter algorithm. The reference image is also fed through a spatial filter and then input to two light valve image subtraction systems to produce difference image approximations of two partial derivatives. These derivative functions are then digitized and utilized as inputs to the extended Kalman filter algorithm.

Abstract: Flying spot scanner technology is combined with stereo photography in motion to produce two channels of video imagery which can be optically combined to produce the perception of dynamic stereoscopic detail. The scanner generates alternate lines with lateral offset corresponding to the physical separation between stereo photographic pairs to provide two rasters.

Abstract: Using frequency domain techniques, the system measures the complex permittivity and permeability of different materials in the Ku band (12.4 to 18 GHz). The measuring system comprises a dual horizontal-plane sectoral horn and sample holder assembly. The two horns are placed mouth-to-mouth with the sample holder between them. An input signal is supplied to one horn. The reflected signal from the sample comes back out from the same horn, while the transmitted signal goes through the sample and out via the other horn. The signal source is a frequency synthesizer. A network analyzer and a computer are used to determine the complex permittivity and permeability from the transmission and reflection signals.

Abstract: The leads to a heater for an electrothermal hydrazine monopropellant thruster comprise tungsten conductors wrapped with smaller diameter tungsten support wire and insulated with beads of alumina (Al.sub.2 O.sub.3). A transition section connects the leads to regular leads. An attaching support wire is attached to the heater at one end and to the transition section at the other end. The insulated conductors and attaching wire are wrapped together with nickel ribbon to form a sheath.

Abstract: A radar system testing apparatus for use in evaluating radar performance of terrain following, forward looking radars, generally installed in the nose of military aircraft. The operator inputs the antenna position and rotational arc limits desired which are converted into reference voltages and compared to the antenna's true position by a logic comparator network. When the true position is within the operator's selected window, and the radar system inputs a trigger signal to indicate transmitter firing, the logic network will respond with a spiked waveform. This waveform traverses two consecutive one shot multivibrators with appropriate controls to vary the width of the resultant output pulses. By controlling the size of the pulses, the operator effectively selects a variety of target ranges and target widths for testing purposes. These controlled pulses are fed back into the radar system where they generate a simulated target return for evaluating the performance of the radar system under known conditions.

Abstract: An instrument having a multi-segmented cup core of a high permeability material with a center post. The outer wall of the cup contains equidistant holes and slots through which a plurality of individual windings are constructed to form a circular array of pick-up coils. A primary winding or search coil is constructed around the center post. Excitation of the search coil induces eddy currents in adjacent multi-layered bolt hole regions which in turn produce a voltage in each of the pick-up coils. As a crack in the material under test will cause an abnormal distribution of eddy currents, a comparison of the voltage measurements of the specimen under test with those of a reference sample will detect the presence of a crack and its corresponding orientation.

Abstract: A sidelobe canceller using only a widely spaced auxiliary array can lose performance for multiple jammers located at angles corresponding to the grating lobe structure. The degradation is independent of the number of control loops used. A closely spaced auxiliary array cannot resolve and process closely spaced jammers but is less susceptible to grating lobe occurrences. Its performance can degrade for closely spaced jammers while the widely spaced array has the resolution capability required. A dual array approach comprised of both widely and closely spaced subarrays was simulated and tested. Each subarray automatically compensated for the deficiencies of the other. The computer simulations predicted the precise nature and locations of these geometrical conditions when the system was tested. Auxiliary channel preprocessing can successfully be used with the dual array approach to simultaneously minimize the differential level problem for multiple jammers.