Abstract: Broadband, monolithic, planar m.times.m and m.times.n transfer switches with diode switching elements are disclosed. Symmetry of the switches maintain equal insertion amplitude and phase performance. Compensation of phase unbalance caused by diode parasitic capacitance is provided by inductors serially coupled between the diodes and the input and output terminals of the transfer switch. Stripline transmission lines are utilized and isolation between the transmission lines is provide in regions of stripline cross over in the plane.

Abstract: A shell structure for a collinear coaxial element array antenna is made of electrical conducting material and includes first and second circular sections separated by a web. The first circular section has an inner diameter that is slightly larger than the diameter of an inner conductor in a coaxial line element of the array antenna, while the second circular section has an inner diameter that is equal to that of an outer conductor of a coaxial transmission line element. The separations of the centers of the first and second circular sections are established by the wed to be equal to the distance between the centers of two adjacent coaxial transmission line elements in the array antenna. The inner conductor of a coaxial transmission line element is inserted in the first circular section and is electrically connected thereto.

Abstract: A fast and accurate temperature controller for a device heated by current through a resistive element, such as various air data probes, wherein the resistance of the element varies with temperature. The temperature controller samples the temperature by selecting the resistance value of the resistive element. Analog calculations are performed based on the instantaneous applied voltage and current returned through the resistive element. Current through the resistive element is controlled by comparing the resistance of the element to a resistance value selected in accordance with the temperature characteristics of the element. Insensitivity to voltage and frequency variations is provided with a highly reliable and uncomplicated circuit having a small number of components.

Abstract: A variable buoyancy buoy includes a shell and expansion apparatus. The two are combined in a manner to provide a watertight structure with an internal region wherein a constant pressure is maintained that is substantially equal to the pressure at a predetermined depth below the water surface. At depths above the predetermined depth the internal pressure is greater than the external water pressure. This differential pressure causes the buoy to expand, thereby increasing its buoyancy.

Abstract: Clutter reduction is accomplished by dividing the sampling times of received radar signals into blocks containing a plurality of sampling times. The average clutter value in each block is estimated by averaging the signal returns for the sampling times in the block. Block average clutter values are time positioned at a selected sampling time position in a block and a smooth function with continuous first and second derivatives is passed through the average clutter value points. In a preferred embodiment the smooth function is a cubic spline comprising third order polynomial segments between average clutter value points. Clutter values at the sampling points are extracted from the smooth function and respectively subtracted from the received radar signals. A clutter sensor examines the resulting radar signals for clutter distortion and eliminates radar signals that are not substantially clutter free.

Abstract: The liquid crystal display includes a patterned mirror disposed between the backlight assembly and the black matrix to reflect light back into the backlight assembly that otherwise would impinge on the black matrix. Apertures through the patterned mirror are so shaped that parallax effects with respect to the black matrix provides desirable luminance versus viewing angle profiles.

Abstract: A method and apparatus for resolving Doppler frequency shift ambiguities in pulse Doppler radar systems provides a radiated signal that is modulated with a periodic waveform having a plurality of pulses within a period, the interpulse intervals between pulses in the period being unequal. Radar target returns are autocorrelated for a plurality of lags, which may include the interpulse intervals and linear combinations thereof. The calculated arguments .theta..sub.Ci of the autocorrelation function are unwrapped by adding 2k.sub..pi., k=0, .+-.1, .+-.2, . . . , to the phase .theta..sub.C1 obtained for the shortest lag T.sub.1 and determining an integer m.sub.k2 from .vertline.(.theta..sub.C2 +2m.sub.k2 .pi.)-(T.sub.2 /T.sub.1).theta..sub.C1 .vertline. <.pi. and then setting .theta..sub.2 =.theta..sub.C2 +2m.sub.k2 .pi.. Phase angles .theta..sub.3, .theta..sub.4, . . . , .theta..sub.m are unwrapped in a similar manner, the integer m.sub.ki being determined from .vertline.(.theta..sub.Ci +2m.sub.ki .pi.)-(T.

Abstract: Magnetic finder fingers, made of a flexible magnetic material are positioned in a holder in a manner to provide independent movement for each. The independent movement permits the fingers to be swept over a surface to retrieve metallic objects. An alternate arrangement has the magnetic finder fingers in a holder so that the entire length of each magnetic finder finger may be placed in contact with the surface.

Abstract: A multigap liquid crystal color display having RED, GREEN and BLUE pixels with TFT activating transistors and with the pixels being constructed and arranged so that the offset voltages at the RED, GREEN and BLUE pixels induced by the gate pulses applied to the TFTs are equalized. In one embodiment, the pixel storage capacitors are customized to equalize the offset voltages. In a second embodiment, the pixel areas are adjusted so as to provide the offset voltage equalization.

Abstract: A spectral moment estimator includes a first processor which processes signals representative of the magnitudes of complex autocorrelation functions of a signal at a plurality lags and provides Doppler spectral width representative signals and the autocorrelation function at zero lag independent of noise. A second processor, processes the complex autocorrelation representative signals, the complex autocorrelation functions phase angles representative signals, and the Doppler spectral width representative signals to provide the mean Doppler frequency of the the signal. The autocorrelation function phase angles are disambiguated and the unambiguous phase angles are least mean square error fitted to a third order odd polynomial, the linear term of which is the mean Doppler frequency of the signal.

Abstract: An element responsive to acoustic particle acceleration for sensing acoustic signals in a region of low acoustic pressure is disclosed. The element may be isolated from acoustic noise when positioned adjacent an acoustic noise generating high acoustic impedance structure by a baffle which provides isolation from radiated and evanescent acoustic signals and structure vibration.

Abstract: A microburst precursor detector samples radar returns from meteorological radar signal reflectors and processes the signal returns in a statistical manner to determine average radar reflectivity and to extract Doppler signal parameters. The vertical velocity in still air and the vertical velocity of the meteorological radar reflectors are respectively determined from the average reflectivity and the Doppler signal parameters. The difference between the two vertical velocities is taken to determine the vertical wind velocity. The vertical wind velocity and the average reflectivity are processed to predict the occurrence of a microburst.

Abstract: A modulator for providing modulating voltages across the anode and cathode of a negatively pulsed magnetron includes a switch which, when activated, couples the modulating voltage source to the cathode terminal, a current regulator which maintains a constant current flow through the anode and cathode when the modulating voltage is applied, and a voltage control circuit that reduces an excessive time rate of voltage change across the switch caused by arcing across the anode-cathode gap. A filament power supply is provided which supplies filament current while isolating the modulating voltage at the cathode from high voltage sensitive components in the filament power supply.

Abstract: A method for teaching reading utilizes a reading guide having a letter director at one end which the student positions at the top of the first letter in each word read. As the student glides the reading guide from first letter to first letter the student is instructed to sub-vocalize the words read and to stop after reading the first sentence. After determining what the student previously knew about the subject matter and what has been learned the student continues, stopping periodically to question what has been learned until the all the material has been read.

Abstract: A half-tone liquid crystal display panel having half-tone pixels, each comprising a plurality of sub-pixels including first and second sub-pixels. Activation voltage is supplied to the first sub-pixel from a TFT switch and to the second sub-pixel from the TFT switch through a coupling capacitor. The second sub-pixel includes a storage capacitor. Sensitivity of the activation voltage applied to the second sub-pixel resulting from capacitance non-uniformity across the panel is reduced by forming the coupling capacitor and the storage capacitor of the second sub-pixel with the same depositions utilizing a common dielectric layer. The capacitance of the storage capacitor of the second sub-pixel is designed large compared to the capacitance of the second sub-pixel.

Abstract: An element responsive to acoustic particle acceleration for sensing acoustic signals in a region of low acoustic pressure is disclosed. The element may be isolated from acoustic noise when positioned adjacent an acoustic noise generating high acoustic impedance structure by a baffle which provides isolation from radiated and evanescent acoustic signals and structure vibration.

Abstract: An array of collinear coaxial lines utilizes standard size brass tubing with brass rods inserted therein to establish each half-wavelength coaxial section. A coupler positioned between each half-wavelength section has an outer conductor supports and through passages for the inner conductor. Inner conductors of the transmission line elements are soldered to the outer conductors of the respective adjacent transmission line elements so that all elements are excited with the same phase and polarity. Air dielectric between the inner and outer conductors provides a transmission line wavelength equal to that of free space so that the length of each element in the array is a free space half-wavelength long, thereby providing an antenna gain greater than that achievable with transmission lines having solid dielectric supporting the inner conductor.

Abstract: A threshold setting circuit receives a signal coupled to the signal terminal of a comparator, delays then amplifies the signal and couples the delayed-amplified signal through a switch to the threshold signal terminal of the comparator. Prior to the reception of a signal which exceeds the threshold, the threshold level is set at the amplified noise level which is stored in storage means coupled to the threshold signal terminal. When the signal exceeds the amplified noise level, the switch is opened prior to the time that the delayed amplified signal is coupled to the threshold signal terminal and stored with the amplified noise in the storage means. Sometime after the signal ceases to exceed the amplified noise threshold level the switch is closed and the storage means tracks the amplified noise to maintain a current threshold level.

Abstract: A structureborne noise isolator employs a two axis system whereby a noise generating platform is coupled to an inner frame by a first pair of diametrically positioned noise isolators, the inner frame being coupled to an outer frame by a second pair of diametrically positioned noise isolators. At least one noise isolator comprising a coil spring shrink fitted at one end to an inner housing and at the other end to a cover. The inner housing is inserted into an outer housing with a damping compound between and potted to the inner and outer housings. Additional damping compound is bonded to the base of the outer housing separating the base of the outer housing from the base of the inner housing. The cover, having damping compound bonded thereto, is coupled to the outer housing. A hub, positioned adjacent to the damping compound on the cover, is coupled to the inner housing.

Abstract: A microburst precursor detector utilizes a multiplicity of radar beams and samples radar returns, in each beam, from meteorological 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.