Abstract: A system for encoding and decoding a binary encoded text message using coxt-based error detection and correction implements the stops of: a) defining a dictionary of m dictionary words, W.sub.i, where each dictionary word is assigned a unique binary code word, represented by a series of bits, and an identifier, IDFR.sub.i such that for any two words W.sub.p and W.sub.q from the dictionary, if IDFR.sub.p =IDFR.sub.q, then the binary code word for the word W.sub.p differs from the binary code word for the word W.sub.

Abstract: In an umbrella top-loaded monopole (UTLM) antenna, the charge distribution n top-load radials increases approximately linearly from the top of the antenna because the activated top-load wires are separating from the tower and each other at the same time they are getting closer to ground. The UTLM antenna of the invention incorporates a top-load configuration in which top-load elements, whether they be radiating or receiving, are arranged in sections of rhombic-shaped frames that originate at the top of the antenna and that extend away from the antenna towards the antenna's base where, at those points of the configuration furthest from the antenna tower and closest to ground at least two top-load elements converge to shield each other and hence reduce charge density. The top-load sections are disposed between the vertical guy wire planes of an antenna to ease their installation, repair and maintenance. The self-shielding effect of the invention permits an antenna to operate at considerably higher voltage.

Abstract: A method for the fabrication of active semiconductor and high-temperature superconducting device of the same substrate to form a monolithically integrated semiconductor-superconductor (MISS) structure is disclosed. A common insulating substrate, preferably sapphire or yttria-stabilized zirconia, is used for deposition of semiconductor and high-temperature superconductor substructures. Both substructures are capable of operation at a common temperature of at least 77 K. The separate semiconductor and superconductive regions may be electrically interconnected by normal metals, refractory metal silicides, or superconductors. Circuits and devices formed in the resulting MISS structures display operating characteristics which are equivalent to those of circuits and devices prepared on separate substrates.

Abstract: A translation system for directing an optical signal through predetermined oordinates of a window mounted in a soil penetration probe includes a tube having a sidewall and an aperture through said sidewall; an optically transparent window mounted in said aperture; an optical system for emitting an optical signal through said aperture; and a translation mechanism mounted within said tube. The translation mechanism may be selectively operated to translate independently and simultaneously the optical system along two orthogonal vectors so that the optical signal scans across the window. Scanning the optical signal extends the useful life of the window before its transmissibility becomes too impaired by damage caused from the optical signal.

Abstract: A wavelength independent optical probe comprises an optical waveguide, a arizing beamsplitter, an optical detector, a quarter-wave plate, a focusing mirror, and a probe enclosure.

Abstract: This invention relates to radio navigation systems and is particularly dited to means for transmitting range and azimuthal information to selected receivers only. More specifically this invention relates to a R-O navigating system in which the signal is so concealed in noise that the signal is of use only to friendly, as distinguished from enemy receivers. By this system enemy aircraft, in a military sense, cannot `home` on either the shipboard or land-based beacons. Mobile equipment of the system of this invention is passive and is, hence, not subject to detection.

Abstract: A method is described for detecting weak signals in a non-Gaussian and non-stationary background using a hidden Markov parameter estimator. The method comprises the steps of: a) partitioning input data into sets of range bins, where the input data has a noise component; b) estimating hidden Markov model parameters from the input data; c) determining the average intensity I.sub.i of the range bins, where i represents an index for the ranges bins, and 1.ltoreq.i .ltoreq.R, and R represents the total number of range bins; d) estimating the average noise intensity N.sub.i of each range bin; e) determining the residual intensity estimates .rho..sub.i of each range bin as the maximum of 0 and (I.sub.i -N.sub.

Abstract: An improved fiber optic Raman sensor (FORS) provides high sensitivity and fective rejection of Rayleigh backscatter and background Raman emissions. Multiple receiving optical fibers are arranged around a transmitting optical fiber to increase the sensitivity of the sensor to Raman emissions from an analysis sample. A Raman emission filter is coupled to the transmitting fiber for preventing output of Raman emissions from the optical fiber to the sample, and a Rayleigh line filter is coupled to the receiving optical fibers for removing Rayleigh line energy emitted by the analysis sample. Rayleigh backscatter emitted by the analysis sample is reduced by orienting the sensor at an appropriate angle with respect to the surface of the sample.

Abstract: An antenna integrates a planar structure, wideband compact design, permitg phasability, into a single structure. The antenna design makes it possible to implement the antenna throughout the entire electromagnetic spectrum with little or no need for impedance matching. The antenna comprises a plurality of exponential-spiral shaped antenna arms in which each of the arms has a radially inner and radially outer end and in which the radially inner ends are spaced rotationally about a common axis, and in which the arms are separated circumferentially from each other in proportion to their distance from the common axis. Each of the spiral antenna arms includes an antenna element having a sinuous portion that has amplitude and period characteristics that vary in proportion to their distance from said common axis. The antenna elements are selectively coupled to an antenna feed.

Abstract: A signal processor utilizes a globally nonlinearly coupled array of nonlinear dynamic elements. In one embodiment of the invention, these elements take the form of bistable overdamped oscillators. The processor exploits the phenomenon of stochastic resonance to amplify a weak periodic signal embedded in noise. In this signal processor, a system or plurality of nonlinearly coupled overdamped oscillators is subject to a weak periodic signal embedded in a noise background. For communication or detection applications, this weak signal component is the signal of interest. A reference oscillator is chosen from the plurality of overdamped oscillators, and is given a time scale for relaxation that is longer than the remaining oscillators. The output of the reference oscillator is analyzed for signal processing purposes in response to the signal and noise.

Abstract: A method for manufacturing a semiconductor structure having improved light mitting characteristics includes the step of exposing a semiconductor substrate, such as a silicon wafer, to an unbiased etching solution comprised of an acid, water, and an oxidizing agent to form a porous region having interstitial spaces in the semiconductor structure. Next, an electrically conductive contact structure is formed in the interstitial spaces and on the semiconductor structure. The large surface area at the interface junction between the electrical contact layer and the porous region is believed to enhance the intensity of light emitted by the porous region by allowing increased electrical current flow across the interface junction.

Abstract: A method and apparatus is presented for crystallizing a thin film on a surate by generating a beam of pulsed optical energy, countouring the intensity profile of the beam, and illuminating the thin film with the beam to crystallize the thin film into a single crystal lattice structure.

Abstract: An electrochemical cell comprises a cell body having a sample chamber, a working electrode fitted through the cell body and extending into the sample chamber; a counter electrode extending through the cell body into the sample chamber; a reference electrode extending through the cell body into the sample chamber; a window which fits over the cell body; and a cap threaded to the cell body for sealing the window against the cell body. An O-ring fitted between window and the cell body provide a leak proof seal. The cell body may be to made of chemically resistant material and be small enough to fit inside the sample chamber of a spectrometer. An O-ring interposed between the cell body and window provides a leak-tight seal, obviating the need for epoxy cement or other sealing compounds so that the cell may be easily disassembled. The cell may be used to monitor electrochemical reactions of moisture and oxygen sensitive materials, as well as electrochemical reactions of corrosive materials.

Abstract: A dual orthogonal inverted L near vertical incidence skywave antenna incls two orthogonal RF loop elements coupled to a ground plane. The first RF loop element is mounted in a first plane and has first feed and ground nodes. The second RF loop element is mounted in a second plane substantially orthogonal to said first plane, and has second feed and ground nodes. The first and second elements are feed from a center feed node and are coupled to the ground plane at different locations. An important performance characteristic of the antenna is that it has no nulls in its azimuth pattern.

Abstract: An article of protective clothing includes a hardened armor section such as impact shields and an underlying layer incorporating one or more inflate fluid cavities or cushions. The fluid cavities are in communication with a reservoir of fluid under pressure. The reservoir can be used in conjunction with an impact sensor that directs the fluid to the cushions upon projectile impact or can be directed to supply fluid to the cushions upon user demand. In either case, inflation of the cushions is only accomplished when needed, thereby enhancing the comfort of a user.

Abstract: A video display with integrated control circuitry formed on a single dielectric substrate, includes a dielectric substrate; emitter cathodes formed on the dielectric substrate for emitting electrons; a window plate mounted a fixed distance from the substrate to define a vacuum chamber therebetween; phosphors mounted to the window plate which generate light when irradiated with the electrons; and field effect transistors mounted to the substrate which are electrically interconnected to the emitter cathodes for selectively controlling light emissions from the phosphors.

Abstract: A stochastic resonator signal detector comprises a multi-stable nonlinear device for coupling to an input signal and a control signal coupled to the multi-stable nonlinear device for varying asymmetry among stable states of the multi-stable nonlinear device. The interaction of the input signal with the control signal in the multi-stable nonlinear device generates an output signal having an amplitude responsive to the input signal amplitude and a frequency range that comprises harmonics of products of the control signal and the input signal.

Abstract: A method for determining the positions of the N array elements of a random rray to an accuracy sufficient to accomplish beam forming is provided where the initial positions of the array elements are known to an accuracy of .lambda..sub.min/2, and where .lambda..sub.min is the wavelength of the highest frequency of any of the M cohering sources which are in the field of the array and where the relative directions are unknown. The method includes the steps of: identifying M cohering sources in the field of the array, each of which emits at least one narrowband frequency, each frequency differing from the adjacent frequency by 1/T, where T is the time period of the measurements; a device for measuring the true bearing of one of the M sources; receiving the M cohering signals at the N array elements; performing a Fast Fourier Transform (FFT) on each of the N element signals; examining the spectrum of each of the N received signals; and from the N spectra, selecting M (M>3) lowest angular frequencies, .omega..

Abstract: An antenna performance monitor comprises an antenna sensor for coupling to n antenna radiating a radio frequency signal. The antenna sensor generates signals Vm and Im representative of the antenna input voltage and current. An A/D converter is coupled to the antenna sensor for digitizing signals Vm and Im. A data processor is coupled to the A/D converter for generating outputs representative of impedance magnitude and phase angle of the antenna substantially concurrently with changes in frequency of the radio frequency signal.

Abstract: A buoyed sensor array communications system comprises multiple sensor syss electrically connected to a signal transmission line which are positioned at predetermined locations along the signal transmission line to form a linear sensor array. Each of the sensor systems generates a data signal in response to receiving an address signal. The system further includes; a processor system electrically connected to the signal transmission line for transmitting address signals to enable any one of the sensor systems at a time in a selectively accessed order and has a data storage memory for storing the data signal from each of the sensor systems as stored data. A radio frequency transmitting system is coupled to the data processor and transmits the stored data at a predetermined time. A negatively buoyant structure connected to the signal transmission line pulls the communications system to the bottom of a body of water upon deployment.