Abstract: A code-enhanced, multi-user detection, Reduced Algorithm Receiver in a multiuser communication system reduces the signal processing requirements by limiting the number of searches between consecutive symbol cycles using information from an encoder state diagram. The Receiver makes use of a convolutional encoder's state machine properties to mark possible transitions as invalid based on the current state of the multiple users'encoders, thus removing them from the search tree.

Abstract: A radial diffuser having insert rings for providing microturbulence to a paper fluid stock suspension and uniformly discharging the fluid stock via a plurality of tubes around the perimeter of the radial diffuser to a paper forming unit including a headbox. The radial diffuser comprises a cover, a main head body, an inlet feed pipe and a plurality of flexible or rigid circumferential discharge tubes. The main head body comprises either one or a pair of the co-axial ring inserts which form a fixed or variable passage or space in the chamber of the radial diffuser. The co-axial rings enhance fluid stock fiber mixing as the fluid stock flows through the radial diffuser head. The plurality of outlets around a side wall of the radial diffuser have removable housings for varying entrance coefficients to facilitate the pumping of the fluid stock suspension into the radial diffuser.

Abstract: A sound absorbing substrate for use as an underlayer in a flooring structure including a subfloor. The substrate is made of a resilient material and more particularly of recycled tires and comprises a bottom surface sized to cover a given surface area. This bottom surface is provided with cavities that preferably consist of parallel grooves extending at an angle of about 45° with respect to one side edge of the substrate. These cavities leave a portion only of the bottom surface in contact with the subfloor. The surface ratio of the portion of bottom surface in contact with the subfloor to the given surface area covered by the bottom surface ranges from 20 to 65%. Such substrates can be of reduced thickness while still having good sound absorbing properties.

Abstract: A miniature, computerized component, variable interference imaging spectrometer (C2VIFIS) system for airborne remote sensing data acquisition with a two dimensional field of view. An alternating staring/scanning method is used to optimize a pushbroom hyperspectral image data set with a photogrammetric reference. Synchronized CCD-imager sensor modules or cameras are aligned to a common field of view. One imager module has a visible range variable interference filter on its surface, a second imager module has a near-infrared range variable interference filter on its surface, and a third imager module has a bandbase filter attached to the imager. Video data from the three sensor modules is digitized and recorded in real time. Further, such video data is monitored by a computer and used to control the shutter exposure of each of the three sensor imager modules. Wavelength spectral image data and directional spectral image data are acquired by a single pass over a target area.

Abstract: A transmit/receive (T/R) module of a phased array radar having a unified housing comprising an integrated connector as part of the module housing, thereby eliminating a hermetic joint between a group of DC signal pins and the module housing. Power and RF signal connector pins are provided in the housing. The pins of the connectors are inserted within the module housing with a glass compression seal around each pin.

Abstract: An automated electronic module inspection system having illumination sources that produce digitized gray scale images that are then analyzed by a computer. The inspection system illuminates the module including solder joints, components and printed circuit board using a sequence of illumination that produce visual images which are used to identify defects. The inspection system inspects for all defects as specified in MIL-STD-2000A (Section 4.4) by using both surface reflectance properties as well as topological properties of objects. The system comprises two video cameras. A positioning table aligns a module-under-test with the optical axis of each camera thereby enabling the same field-of-view to be observed under different lighting conditions. A dark field illumination associated with a first camera preferentially illuminates non-flat surfaces, but not vertical surfaces. A bright field illumination associated with a second camera preferentially illuminates relatively flat surfaces.

Abstract: An optical beam switch is disclosed for sequentially pointing a laser beam to a plurality of terrestrial target locations at predetermined depression angles and at angular positions relative to a reference direction. The switch includes a CW laser whose collimated output beam is directed into a rotating retroreflector. The moving beam reflected therefrom describes a continuous circular path across the upper surface of a beam deflection device. The beam deflection device comprises a plurality of beam refracting prisms. The index of refraction and angulation of each prism determines the depression angle and azimuthal angle of the deflected beam. The depression angle is held precisely constant as the incident beam describes its arcuate path across the upper surface of the prism. The retroreflector may comprise three mutually-perpendicular mirrors, joined at a vertex, for providing a reflected beam parallel to and displaced from the incident beam.

Abstract: A fixed frequency, series resonant converter having a resonant snubber comprising an inductor and capacitor connected across a tank circuit of the converter. An optimum amount of inductance in the resonant snubber minimizes the degree of "shoot-thru," or conduction through a body-diode within a transistor switch of the converter caused by ringing, which allows for nearly sinusoidal current to be provided to a full bridge high voltage rectifier enabling the power converter to operate at a higher frequency. An alternate embodiment applies the resonant snubber only across a selected transistor switch.

Abstract: A phased array radar, solid state, module retention apparatus having a tool operated tubular assembly at an antenna radiator end of a dual channel T/R module and a wedge structure at the module's connector end. A single rotational motion of the tubular assembly by the tool is translated into linear motion in two orthogonal directions. During installation of the module into a subassembly tray, the tubular assembly translates the module into the connector and wedge structure while simultaneously locking the module in place and applying compressive forces that press the module base at the antenna radiator end of the module against a cold plate of the tray. The wedge structure forces the module base at the connector end of the module the cold plate of the tray as the module translates into the tray connector. The tubular assembly has a helical cam that translates the module toward the connector as it is rotated.

Abstract: A synthetic aperture radar guidance system adapted for use in a guided missile is described wherein the frequency of the transmitted pulses changes with time with a chirp slope which varies with range. The time between pulses also changes as a function of range. The desired values of the chirp slope and the interpulse interval are computed for all values within a range of interest and stored. Furthermore, the operating parameters of the SAR are changed as the range changes. The time intervals and frequencies are selected to avoid interruption ambiguities and eclipsing. The phase and frequency of the synthesized signal are controlled to adjust for motion of a vehicle on which the SAR is mounted. The SAR is operated in several modes. In a search mode, the beam of transmitted pulses is steered across a mapping area to form a plurality of patches of the mapping area. The patches are combined into one map of the entire area. Each pixel of the map is compared with a target template until a match is provided.

Abstract: An improved Doherty amplifier for operation at microwave frequencies using microstrip circuit technology and gallium arsenide devices to achieve greater efficiency and linearity. The circuit divides the input power equally between a carrier amplifier and peak amplifier with a quarter-wave delay at the input to the peak amplifier insuring that the output power of the two amplifiers will be in phase at the load. A three-port network combines the phase-delayed carrier amplifier output with the output of the peak amplifier. The outputs of the two amplifiers are connected together by a quarter wave transmission line of impedance R. A load of one-half the optimum load (R/2) is attached to the output of the peak amplifier. A quarter-wave line section provides the transition from R/2 to the desired impedance, R. When the peak amplifier is off, its output impedance is infinite and the output power of the carrier amplifier is delivered entirely to the load.

Abstract: A method for applying an extremely thin layer of an adherent material to a substrate at a controllable rate. The disclosed embodiment provides a method for depositing a thin layer of titanium, typically much less than 100 Angstroms, on a silicon dioxide substrate layer in order to provide the necessary adhesion for a metallic film. A silicon wafer having a layer of silicon dioxide is placed on a titanium precoated carrier in an evacuated chamber. The wafer and carrier are then sputter etched using argon as a sputter etchant while titanium is deposited onto the wafer. The ratio of deposition rate to etching rate is controlled to provide a very low effective deposition rate. Thus, while the surface is being atomically cleaned, the adhesive layer is simultaneously deposited. A film of a noble metal, typically platinum, may then be deposited onto the adhesive layer. In an alternative embodiment, the titanium is sputter deposited from a target while the substrate is simultaneously sputter etched.

Abstract: A phased array antenna having two stages of time steering control that achieve system performance requirements at minimum cost. The first-stage which is traditionally located at the subarray level, is a multi-bit time delay unit that has a sufficient number of bits to meet the system's range resolution requirements. The second-stage located at the radiating element level, is a single-bit time delay unit that meets the system's two-way instantaneous bandwidth requirements. This combination of first-stage and second-stage time steering control minimizes the number of subarrays required to achieve the system performance requirements.

Abstract: A ring laser gyro uses a nonplanar path having at least one plane of mirror symmetry and two pathlength control mirrors in order to reduce scatter variations occurring during the operation of the laser gyro. The mirrors used to produce such path are fixed to an isotropic supporting block having passages therein that define the path segments and the mirrors are moved out or in by the expansion or contraction of the block. The two pathlength control mirrors are disposed diagonally opposite each other on the plane of mirror symmetry, and are placed on substrates whose positions are controllable, each substrate being coupled to means for controlling the positions of the substrates as a function of the pathlength. With such a mirror configuration, the pathlength may be held constant by a suitable control means and the relative movement of the mirrors constrains movement, with respect to the mirrors, of the beams circulating in the path to directions perpendicular to the planes of incidence on the mirrors.

Abstract: The RF input of a radio receiver is converted to IF including received signal, noise and interference and fed to an interference detector and to an interference canceler of an interference suppressor. A fast Fourier transform (FFT) at the front end of the interference detector detects samples of all the interferences in the frequency domain. The frequency domain samples are scaled for gain control and detection of interferences above a predetermined threshold. The interference detector suppresses interferences to the predetermined threshold level. The scaled frequency domain interference samples are phase rotated and fed to an inverse fast Fourier transform to obtain a time domain replica of the interferences which are phase shifted replicas of the detected interferences.

Abstract: A ferrite stripline circulator having low cost, broad tolerance elements and an easy to assembly design. The unit comprises of a cylindrical housing into which are stacked a ferrite disk, a center conductor, another ferrite disk, a metal ground plane, a disk magnet, a metal cover and a compression spring. A C-clip, that fits into a groove on an upper inner circumference of the cylinder, forces the compression spring against the cover and thereby applies the pressure that is required to assure proper operation of the stacked elements.

Abstract: Spurious frequencies are suppressed in a transmitter by an RF pulse fall time controller circuit comprising a quadrature hybrid matched attenuator located between a predriver and the first stage of class "C" driver amplifiers. The circuit linearly attenuates RF pulses and slows pulse fall time. Operation of the circuit is initiated when the rising edge of a pretrigger starts a pretrigger generator which then triggers the application of current bias to the attenuator circuit. After a controlled period of time, the circuit decreases the forward current bias of PIN diodes in the attenuator thereby increasing the diodes' series resistance and increasing the attenuation of the RF pulses. This creates a slow pulse fall time thereby suppressing spurious emissions caused by parasitic ringing of the cascaded Class C common base transistor amplifiers in the transmitter.

Abstract: A radar target velocity estimator apparatus and method for computing a radial velocity of radar targets from differences in Doppler frequency shift between pulse-returns of multi-pulse waveforms. The velocity estimator uses Doppler frequency shift which is obtained from a finite impulse response (FIR) filter in combination with logarithm tables stored in read-only-memory (ROMs) to calculate the target's velocity. The estimation process requires the calculation of each complex FIR filter value twice during a pulse repetition interval; once for returns of a leading set of radar pulses and then for a trailing set. The estimated velocity is proportional to the phase difference between each corresponding pair of filter values. The estimate is a function of the arctangent of the quotient of the in-phase component of the complex value divided by the quadrature component.

Abstract: A ring laser gyro uses a composition for the gain medium which optimizes the effect of the Fresnel-Fizeau drag on the output signal of the gyro. In one embodiment, a composition of the gain medium is used which produces no change in the Fresnel-Fizeau component of the output signal as the discharge current varies from a nominal amount. In another embodiment, a gain medium composition is used which eliminates the Fresnel-Fizeau component of the output signal at a predetermined level of discharge current.

Abstract: Mode programmable VLSI CMOS data registers perform on-chip self-test. A first data register performs storage or transfer of data, operates in a scan mode or generates pseudo-random numbers (PRN). A second data register performs storage or transfer of data, operates in a scan mode or performs signature analysis. Data initialization of the registers occurs automatically when operating in a test mode.