Abstract: An integrator-multiplier-integrator circuit scheme usable in transverse fers, a transverse filter employing such a circuit, and a method for using each. The multiplier-integrator-multiplier has a capacitatively loaded integrating amplifier fed by a transistor. The current through the transistor, and hence the time it takes to charge the integrating capacitor, depends largely on the bias of the transistor, not the size of the capacitor, permitting one to set and control integration time by setting the transistor's parameters, and controlling its bias, effectively controlling integration time by us of only one semiconductor device. An additional circuit for auto-zeroing (i.e. canceling quiescent offset) increases adaptivity of the circuit. Preferably the phase of inputs to the first multiplier is made selectably variable to minimize phase difference at the multiplier, thus increasing circuit stability.

Abstract: A silicon carbide semiconductor material; and method of making same, in which a doped film of 3C-silicon carbide is grown heteroepitaxially on a 6H-silicon carbide material. Growth occurs at 1200.degree. C. or less, and produces a heterolayer having a reduced bandgap, and hence reduced contact resistance, but which is fabricatable with the less expensive equipment commonly used to fabricate silicon based semiconductors.

Abstract: A sensing apparatus and related method for sensing strain between fiber Bragg grating sensors inscribed in an optical fiber. The fiber is inscribed with a first fiber Bragg grating sensor and a second fiber Bragg grating sensor. A strain detection unit detects strain between the first fiber Bragg grating sensor and the second fiber Bragg grating sensor based on the optical propagation time of light projected into the fiber and reflected by the first fiber Bragg grating sensor and the optical propagation time of light projected into the fiber and reflected by the second fiber Bragg grating sensor. More specifically, light projected into the fiber is modulated with an RF signal. A phase change of the RF signal is determined from the light projected into the fiber and reflected by the first fiber Bragg grating sensor and from the light projected into the fiber and reflected by the second fiber Bragg grating sensor.

Abstract: A scheme for filtering noise from a signal, in which the noise fluctuates significantly in phase. The signal is sampled to produce N members of a time series and the phase of each signal extracted in the form of a magnitude and a phaser, i.e. for a time series .vertline.x.sub.1 .vertline.e.sup.i.theta..sbsp.1, .vertline.x.sub.2 .vertline.e.sup.i.theta..sbsp.2, . . . , .vertline.x.sub.N .vertline.e.sup.i.theta..sbsp.N, where .vertline.x.sub.n .vertline. is the magnitude of the nth member of the N time samples, and e.sup.i.theta..sbsp.N the phaser for the nth sample. The phasers are added to form a complex value s such thats=.SIGMA..sub.N=1.sup.N ?Re(e.sup.i.theta..sbsp.n)+iIm(e.sup.i.theta..sbsp.n)!.Phase noise which fluctuates strongly will tend cancel itself in the sum s, whereas phase resulting from a stable signal will tend to reinforce. Thus the scalar .vertline.s.vertline.

Abstract: A rotational hyper-spectral imager is disclosed. The rotational hyper-spectral imager collects substantially all available photon flux emitted by an object being detected and analyzed and allows the rotational hyper-spectral imager to determine the composition of the objects. The rotational hyper-spectral imager is particularly suited to detect and analyze objects having weak illumination.

Abstract: A method and apparatus for accessing anti-phase states in a nonlinear system by globally coupling an array of oscillators. For N number of oscillators in the system, there are (N-1)| anti-phase (AP) states in phase space. AP states exist where each waveform is staggered out-of-phase with every other wave form. The system is controlled between AP states by means of a linear parameter and a hyper-switch. In an out-of-phase (OP) state the orbit remains on a basin boundary between or among AP states. As the linear parameter is decreased to a specific value, the orbit leaves the basin boundary and enters a canonical invariant region (CIR) towards an attractor. Each CIR contains one AP state and one attractor. Once the orbit has reached an attractor within the CIR it shall remain there until the linear parameter is increased and system again becomes unstable.

Abstract: A method and apparatus for counteracting polarization fading and stimulated Brillouin scattering in long runs of non-polarization maintaining optical fiber. A linearly polarized optical signal is depolarized by phase modulating the signal at a frequency significantly above the fiber's Brillouin scattering linewidth V.sub.b prior to launch into the long run of fiber.

Abstract: An analog-to-digital converter in which an analog input signal is folded by a plurality of folding circuits whose moduli, and hence half folding periods, are mutually prime with respect to one another. Each folding circuit has an associated comparator ladder having one less comparator than the modulus of the folding circuit. The collective output of the ladders, i.e. the states of the comparators in the ladders, uniquely corresponds to input signal magnitude over a dynamic range equal to the product of the folding circuits' moduli, permitting a greater dynamic range for the converter for the number of comparators used.

Abstract: An optical scheme for in situ identification of particulates in fluid such s engine oil, in which a portion of the fluid flow is tapped, fed via a conduit to a pair of optically transparent opposed plates, imaged through the plates, and the fluid returned to the main flow. Imaging is preferably done with a laser and photodetector array, and the output fed to a computer for image processing. Separation between the plates ensures that all the oil therebetween will be in the imaging system's near field.Preferably, the computer counts the number of particles in the oil, and classifies their shape, by scanning the image until it hits an object (i.e. hits an opaque pixel), using known chain code to trace the object's outline, determining the object's aspect ratio, and repeating for each object in the image.One embodiment uses a planar rotary member which is scalloped about its periphery. The scallops act to push oil continuously against an outer casing.

Abstract: A computer driven system which receives time-binned echo strength data, and hich, for each series of echo strengths received, stores the echo strength data in computer memory, and automatically associates with that data the latitude, longitude and time at which the data were generated. From these data, the algorithm classifies the sediments, which produced the echo strengths, determining such parameters as sediment acoustic impedance, porosity, attenuation, grain size, density, acoustic velocity, and shear strength. System software can produce additional result files in which these properties are associated with corresponding echo strength data. Both the raw and reduced data are displayable in human readable form, preferably on a computer monitor, for operator review. System software can also generate navigation plots which trace on a map, preferably on computer monitor, points at which data are taken, and the bottom sediment at those points.

Abstract: A satellite-borne system for the detection of near earth objects. The system periodically captures two images of the celestial sphere about the earth using a pair of linear arrays of optical detectors oriented so that the detectors image lines on the celestial sphere that are separated at each pixel in azimuth by the same angle. The position of the linear detectors is varied for each orbit of the earth by the satellite such that the entire celestial sphere can be imaged. The images produced by the two detector arrays are temporarily stored in memory until they can be processed using frame difference signal processing techniques. The results from the frame difference signal processing are transmitted to a ground station for further processing. The processing on the ground can include object classification, orbit tracking (using a time sequence of differenced frames), and earth collision determination and warning.

Abstract: A radar interference circuit which rejects both continuous noise and shorulse interference signals. A plurality of omni-directional antennas are placed around the main directional radar antenna and connected in differing sets to a plurality of canceller means to each of which the main antenna signal is also connected. The canceller means for each set of three Omnis and the main antenna cancels out the white-noise interference received by that group of antennas. The outputs of the plurality of canceller means are then taken in different sets of two each, subtracted and compared to a threshold signal. If one or more comparator outputs are above the threshold, signifying that the antenna pulse signal is being received through the sidelobes of the antenna patterns, the outputs of these comparators will be a one signal and the OR gate, to which the comparator outputs are fed, will provide an output to blank the radar.

Abstract: An electromagnetic wiggler having a cylindrical member, and a central member disposed axially within the cylindrical member, both of which are formed from alternating cylindrical sections of ferromagnetic and non-ferromagnetic material, each sequential pair of these sections being the length of the wiggler's period .lambda..sub.w. The sequence of sections between the inner and outer members is shifted .lambda..sub.w /2, so that ferromagnetic sections of the outer member are disposed radially opposite non-ferromagnetic sections of the inner member, and vice versa. The resultant radial magnetic flux density in the cylindrical gap between the members is larger and sharper than the flux density for the same wiggler without the central member, permitting higher radiated power output, at higher radiation frequencies, for the same energy of input electron beam.

Abstract: An apparatus and method for converting a signal of arbitrary polarization one of preselected polarization, e.g. for use by a sensor, transducer, etc. A signal splitter divides the input signal into its orthogonal linearly polarized components, and launches the components from a pair of output ports. The signals counterpropagate to the opposite port, and, while counterpropagating, are rotated into the same linear polarization state. In one embodiment, the rotation is done by a pair of complementary 45.degree. Faraday rotators; in another, by one 90.degree. rotator. In the former, the signal is recombined at the splitter in the initial state of polarization that in which the signal initially entered the splitter; in the latter, the recombined signal is of orthoconjugate polarization to the input signal.

Abstract: A method and apparatus are provided for filtering noise from a plurality of input signals in a sensor system. One first main input signal and several first auxiliary input signals are obtained and interior weights corresponding to the first main and auxiliary signals are determined. Thereafter, equivalent linear weights corresponding to the interior weights are determined and the equivalent linear weights are applied to second main and auxiliary input signals to filter the second main and auxiliary signals and produce one final output signal. Alternatively, the first input signals can be a subset of the second input signals such that a large set of input signals can be filtered by calculating weighting factors from a subset thereof.

Abstract: A strain sensor system formed from a laser cavity where changes in length of the cavity are used to measure strain. The cavity can include a passive optical fiber strain sensing section and/or an active doped optical fiber section that lases when pumped by a laser pump. The cavity can be a ring or linear cavity with or without mode locking. The light oscillating in the cavity sets up multiple oscillation modes. The multiple modes create beat modes or frequencies. The measured frequency difference between beat mode frequencies is inversely proportional to the length of the cavity. The measured frequency change in one of the mode frequencies or one of the beat frequencies is proportional to the absolute strain on the fiber. A heavy metal fluoride glass sensing section makes the sensor temperature insensitive.

Abstract: An active impedance modification device or arrangement enables the interaction of sound with a structural surface to be controlled, e.g., so that, reflections from that surface (which can be the hull of a submarine) are substantially reduced or eliminated. The device comprises a coating comprising an inner driver transducer layer in contact with the structural surface an outer receiver transducer layer which receives the sound, in combination with a variable gain, variable phase shift amplifier connected between the interface of the outer layer with the sound carrying medium (e.g., water) and the interface between the second layer and the structural surface. Reflections are reduced by setting the gain and phase shift of the amplifier to simulate the input impedance of the sound carrying medium.

Abstract: A voice communication processing system and method for processing a speech waveform as a digital bit stream having a reduced number of bits representing speech parameters. The bit representation of amplitude parameters is reduced by storing only probable amplitude parameter transitions corresponding to amplitude parameter indices in an amplitude table and by joint encoding the amplitude parameter indices over multiple frames. The bit representation of the pitch period is reduced by storing a range of pitch periods in a pitch table and by joint encoding pitch period indices corresponding to an average pitch period over two frames. The bit representation of the vocal tract filter coefficients is reduced by storing only probable filter coefficient transitions corresponding to filter coefficient indices in a filter coefficient table and by joint encoding the filter coefficient indices over two frames.

Abstract: A machine for producing a graphite fiber tape suitable for use in the protion of metal matrix composites by physical vapor deposition. The machine consists of adjacent air-tight enclosures. Two venturi pipes are located within the enclosures and aligned with a gap between them. A vacuum pump draws air out of one of the air-tight enclosures. Graphite fibers are drawn through the venturi pipes and laterally spread from a tow bundle via the Venturi effect to form a thin tape.

Abstract: A Fourier transform microscope for use in imaging a source of x-ray and/or gamma-ray radiation includes first and second grids arranged in proximity to the source. The first grid includes an arrangement of first subgrids elements with a first predetermined number n of approximately parallel, equally-spaced linear first ribs which are opaque to the radiation of interest, and first radiation-transparent regions which are arranged in alternation with the first ribs. The second grid includes an arrangement of second subgrids elements which are larger than the first subgrids elements, and which have a common field of view with corresponding first subgrid elements. Each second subgrid element has a second predetermined number n+m of approximately parallel, equally-spaced linear second ribs which are opaque to the radiation of interest, and second radiation-transparent regions which alternate with the second ribs. Each first subgrid element and its corresponding second subgrid element is termed a `subgrid system`.