Abstract: A system is presented for enhancing sonar signals wherein Doppler echoes eived in the time domain from a sonar system are processed by digitizing, shifting to baseband, Fourier transforming to the frequency domain, applying a frequency stretching algorithm designed to expand low Doppler signals, retransforming the signal back to the time domain, reshifting from baseband to original center frequency, converting to analog and outputting the resultant enhanced Doppler time domain signals to either earphones of a sonar operator for audio monitoring or for further processing for visual display.

Abstract: An apparatus and method is presented wherein the lens system or assembly is fixed in its location along an optical axis between an object and its image. The focusing of the object, which may vary its position along the optical axis, occurs through adjusting a detection medium or an imager to the position in image space where the image space is focused on its image plane. The invention is structured to facilitate this focusing in an automatic and very rapid manner to accommodate rapid changes in the location of the object along the optical axis.

Abstract: The invention presents a method and apparatus for utilizing a single frequency, self seeding laser pulse signal transmitted to create a target beam to be projected toward an atmospheric target whereby a portion will be reflected back upon itself, and a local oscillator beam constructed to a shape approximating a low level elongated square wave pulse to be heterodyned with the returning target beam. A radio frequency voltage drives an acousto-optic modulator and amplitude modulates the local oscillator beam to form an optical output that is a flat top pulse resembling a square wave function. The local oscillator beam and returning target beam are polarization adjusted to match and are then combined and focused onto detector. The system is effective for use as an aircraft velocimeter.

Abstract: An injection seeded, single frequency ring laser source is presented wherein stabilization and single frequency control is accomplished by measuring the intensity or power of the portion of the high power laser beam generated in the ring slave laser and which is directed to return to the seed laser. When the intensity of the return beam falls below a preset threshold level, the in-phase operation of the laser system has been established and high energy single frequency pulses are generated and emitted.

Abstract: Presented is a device and method for providing a means of driving capacitive cells, such as those comprising suspended particle light valve windows, with a squarewave voltage signal at a select frequency with high efficiency and low power requirements. The invention uses an inductive circuit in parallel with the capacitive load of the capacitive cell, a dc voltage source, and a fast switching means connected to timely control the polarity of the voltage source to the capacitive cell.

Abstract: A method and apparatus are disclosed for controllably filling a confined optical cavity primarily with a volatile fluid suspension where a controlled slight pressure is used to force the fluid into the cavity and is followed by adjusting the equilibrium with a slight negative pressure or possibly atmospheric pressure applied at an exit port to the cavity. This method and apparatus is particularly suited to the filling of light valves which are configured with parallel plates positioned by very small distances between one another to create the cavity which is to be filled with the volatile fluid suspension.

Abstract: A method and apparatus are disclosed for controllably filling a confined optical cavity primarily with a volatile fluid suspension where a controlled slight pressure is used to force the fluid into the cavity and is followed by adjusting the equilibrium with a slight negative pressure or possibly atmospheric pressure applied at an exit port to the cavity. This method and apparatus is particularly suited to the filling of light valves which are configured with parallel plates positioned by very small distances between one another to create the cavity which is to be filled with the volatile fluid suspension.

Abstract: This invention teaches a method of making reliable electrical contact between the driver IC circuits and the TFT matrix array by the use of wire bond connections which are short and which facilitate compact location of the drivers to the frame of a flat panel display or directly to the panel substrate.

Abstract: A single frequency solid state laser has been designed for generation of a high power Q-switch pulse followed by a quasi-CW low power tail by properly controlling the laser resonator transmission via an intracavity Q-switch. The generation of a stable single frequency pulse is accomplished by a primary feedback control system containing a central timing and prelase control unit. Generation and smoothing control of a quasi-CW pulse tail is accomplished through a secondary feedback control system.

Abstract: This invention presents a way to provide night vision viewing compatibility of backlit electrooptic modulated light valve or LCD displays designed for daylight viewing. Liquid crystal displays (LCD) designed with backlighting systems which provide a high brightness, good contrast display under daylight conditions are inappropriate for use in dark, night time conditions where viewing of the display is desired utilizing electronic night vision equipment. This invention describes improvements to standard backlighting displays which through the utilization of arrays of low-level intensity light sources such as secondary fluorescent light sources, miniature incandescent lamps or light emitting diodes, the general means used in daylight vision can be turned off and the secondary low-level lighting sources achieve a minimum intensity acceptable for night vision electronic viewing.

Abstract: A method and apparatus is presented whereby control of the frequency of pulses emitted by a resonant ring slave laser is forced to a single frequency defined by a seed laser through the control of the pathlength of the ring laser resonant path. By monitoring the time difference between turn on of a Q-switch within the laser resonant cavity and the time of occurrence of the output pulse of the slave laser, and effecting changes to the ring laser resonant path in a manner to minimize the measured time difference, the frequency of the output pulse from the slave laser is driven to a single frequency defined by the seed laser resonator.

Abstract: An infrared imaging system is presented wherein a visual image of a scene being viewed is obtained from the thermal energy radiated from said scene. The thermal energy radiated is focused onto a plurality of means for absorbing energy from the infrared radiation, specifically a two-dimensional array of gas cells with the front end being a rigid infrared transparent window, the sides being rigid, and the rear ends being flexible membranes. Infrared radiation absorbed by the cells causes changes in the thermodynamic pressure within each cell and consequent expansion of the flexible membrane on the rear end of each cylindrical cell. The deflection of these flexible membranes is monitored and measured by either a laser interferometer system or a solid state pressure sensing system. Measurement of this deflection represents the amount of infrared radiation received at each of the plurality of gas cells.

Abstract: Apparatus and method for dithering ring laser angular rotation sensors, including a plurality of such sensors with substantially identical natural dither frequencies and having different sensor axes mounted upon a resilient structure; applying energy to dither such sensors; the energy being connected and disconnected from the dithering of each sensor in response to the amplitude of dither of that particular sensor to minimize lock-in; and frequency or phase modulating the energy applied to dithering to avoid continued uni-directional coning effects.

Abstract: A method and apparatus for detecting and identifying Doppler frequency and phase information contained within a signal of the direct sequence spread spectrum type. An incoming signal is split by a circuit and component parts mixed with first and second local oscillator signals, the frequency of the first local oscillator being less than that of the carrier and the second being greater than that of the carrier by the same amount, plus an amount equal to twice the maximum Doppler frequency shift. The heterodyned signals are then low pass filtered, mixed with each other to form a heterodyned output that is then low pass filtered. The resultant signal retains Doppler phase and frequency information and is independent of carrier frequency and modulating PN-code thereby providing an easily demodulated signal whose Doppler information may be readily identified.

Abstract: An apparatus and method is provided wherein a television signal being traitted may be modified by multiplexing in a digital information-bearing signal in a manner that binary pulses are encoded upon horizontal synchronizing pulse windows contained within the composite video signal. The apparatus comprises two primary subsystems, an encoder and a decoder. The encoder is further composed of four components (1) a horizontal synchronous pulse detector, (2) a pulse position modulator, (3) a digital signal conditioner, and (4) a mixer. The decoder consists of three components: (1) a horizontal synchronizing detector, (2) a pulse position demodulator, and (3) a digital signal conditioner. Functionally, the video/digital data multiplexer is a pulse position (PPM) digital communication system which utilizes the leading edge of the horizontal synchronizing pulses of a composite video signal as a marker denoting the location where a pulse will be inserted.

Abstract: The invention presents a digital raster timing encoder/decoder system when television raster synchronization pulses and other timing pulses and information data are generated. The invention comprises a digital clock source having coding circuitry which, combined with the clock source, encodes preselected digital signals containing information on raster synchronization control and timing, and also any other information data that is desired. The encoded signal output is transmitted either directly or via some special transmission link, for example by use of a Manchester Decoder clock multiplier (MDCM) system, to a receiving and decoding circuit. The received signal is decoded to create timing signals for operation control of the video television scanning system, and to read out other desired digital data that has been also transmitted within the signal.

Abstract: The invention is a programmable frequency controller for a frequency agile adar system. The system comprises a microprocessor which includes clock generator, a front panel radar parameter input unit, a program memory, data memory, a front panel radar an input buffer port, a microprocessor data bus, an output buffer port, a front panel display unit, a radar data collection system, a radar synthesizer output buffer unit, a radar frequency synthesizer, and a frequency agile radar system with antenna. The control system operates, monitors, and collects operational data during operation of the frequency agile radar system. Input control parameters are preset at the front panel radar parameter input unit. Program memory contains preprogrammed computer control instructions for the microprocessor in performing control and management of operational data during radar operation. The data memory unit provides capability of storing and transferring data during operation of the system.

Abstract: A tuned gyroscope incorporates a dynamic absorber for lessening the transmissibility of resonant vibrations. A damping mass is symmetrical about a rotating element of the gyroscope. A symmetrical arrangement of elastomeric material is utilized to mount the mass to such rotating element. The mass and elastomeric material are so chosen with respect to geometry and material composition that out-of-phase vibrations are induced within the damping apparatus upon the onset of resonant vibrations to minimize the transmissibility of such vibrations with respect to the elements of the tuned gyroscope.

Abstract: An apparatus and method for automatic character recognition is presented ch automatically locates and recognizes alphanumeric characters in a scene viewed by a raster-scan type of sensor. By this method the apparatus can search the entire scene and recognize up to seven alphanumeric characters in a bounded area of known size by the correlation technique in less than 1.5 seconds. The technique used first locates the bounded area and alphanumeric characters and then performs the recognition. Two different feature extraction methods are used to locate the characters in the scene. The recognition function is performed by correlation using an incoherent electrooptical processor.

Abstract: This invention is an apparatus and method created around a specialized micomputer attachable to and addressable to each thermister in an array of thermisters used to measure temperature in the sea. The invention provides a number of options so that the same model of microcomputer can be adapted to several different modes of operation and used to monitor a variety of other sensors that have electrical resistance, voltage or current as outputs. Alternate modes of operation for resistive sensors are presented where a number that fixes the measurement as a fraction of the dynamic range of the variable being measured is determined. The system includes the circuits and memory needed to adapt it to any of a variety of sensors measuring physical quantities.