Abstract: In a data compression system utilizing the Haar, Walsh or Hadamard transformation, a machine which operates in the transform domain to obtain approximations to the higher order transform coefficients by means of extrapolation from lower order transform coefficients. The extrapolation of the higher order transform coefficients is approximately equivalent to either a linear or to a quadratic interpolation within the spatial or time domain.

Abstract: The frequency of the output beam of a high power krypton fluoride laser is shifted by a plurality of Raman cells arranged successively in the path of the laser beams. These cells each contain a gas selected from the following gases: H.sub.2, HD, D.sub.2 and CH.sub.4, the combination of the gases used being chosen to provide a frequency shift of the beam so as to produce an output in the 330-355 nm range, which is suitable for use in photopredissociation of formaldehyde (HDCO) so as to produce heavy water (D.sub.2 O).

Abstract: A system for demodulating piecewise coherent, combined frequency and phase-shift-keyed signals that are modulateed by orthogonal or biorthogonal code words. Rather than maintain local reference signals in phase-lock with the received signal, the system mixes the received signal with both sine and cosine signals at both the mark and the space frequencies to obtain multiple outputs which are correlated with each of the code words utilized by the system to determine the particular code words that have been received.

Abstract: A system for demodulating a coherent, phase-shift-keyed signal that is modulated by a set of orthogonal or biorthogonal code words. The system does not require a local phase reference that is phase locked with the received signal. The system is made up of two demodulators and a microprocessor. One demodulator utilizes a local sinusoidal signal in the demodulation process, and the second uses a local cosinusoidal signal in the demodulation process. Because the phases of the local signals do not change significantly with respect to the unmodulated phase of the received signal during the period of time occupied by a single code word, the output of one or the other of the two demodulators resembles the code word which was transmitted. The set or orthogonal code words is compared with the outputs of the two demodulators to determine which code word was transmitted, and the data which corresponds to that code word is output by the system.

Abstract: A digital system for demodulating coherent phase shift keyed signals. Maximum likelihood estimates of the unmodulated phase and rate of change of the unmodulated phase of the received signal relative to a local oscillator signal are used to improve the demodulation process. The maximum likelihood estimates are obtained from measurements of the phase of the received signal relative to the local oscillator signal over a predetermined set of keying intervals. The digital demodulation process permits rapid "lock-on" at low signal-to-noise ratios.

Abstract: A machine for detecting image corners in two-dimensional images. The machine transforms two-dimensional images by means of the Haar transform into the two-dimensional Haar transform domain. Certain of the Haar transform coefficients, which are sensitive to corners, are compared to a threshold and an output indicative of a corner is generated whenever a corner sensitive transform coefficient exceeds the threshold.

Abstract: A machine for detecting image spots in two-dimensional images. The machine transforms two-dimensional images by means of the Haar transform into the two-dimensional Haar transform domain and calculates a "double difference" between each Haar transform coefficient and the adjacent coefficients in the immediately preceding rows and columns. For certain of these "double differences" which are sensitive to spots, the invention outputs a spot indication and address whenever the absolute magnitude of the "double difference" exceeds a threshold.

Abstract: An electrically excited gas laser having a dual-purpose electrode configuration. Two long parallel metal electrodes on opposite sides of the gas volume are almost totally enclosed in a dielectric body material. A raised projection of each electrode, at opposite body ends, is in direct contact with the laser gas. A conventional pulse generator is connected to the electrodes. When a pump pulse is applied, a transverse glow discharge is initiated which rapidly gives way to a main longitudinal discharge. In an alternate arrangement, the electrodes comprise several discharge sections in series along the laser body, connected in electrical parallel to the pulse generator.

Abstract: Four radiant energy detectors are arranged in a common plane in a substantially square configuration with each detector occupying a separate quadrant. Infra-red energy received from a target is focused onto the detectors by means of a lens, there being a chopper positioned between the lens and the detectors to chop the radiant energy in a periodic fashion. The outputs of diagonally opposite pairs of detectors are each directly fed to a separate differencing amplifier, where difference signals are generated. These difference signals are then added together and subtracted from each other in separate circuits in a predetermined manner to produce a first signal representing the departure in azimuth of the target from a reference axis running through the center of the detector array, and a second signal representing the departure in elevation of the target from this same axis.

Abstract: A Doppler radar signature simulator decoy for protecting a helicopter under attack by hostile weapons which home in on a Doppler radar return signal from the helicopters rotors. The decoy returns a strong radar signal which duplicates a relatively weaker signal emitted from the helicopter rotors, leading hostile weapons to the decoy.

Abstract: A noise-cancellation scheme in a system receiving acoustic information signals, where the system is carried in a vehicle having self-generated engine noise. An engine rotation sensor generates pulses driving a synchronous type filter device which passes only the engine noise frequency and its harmonics. The latter signal is then subtracted from the total input signal having information and noise combined. One filter circuit comprises a phase-locked loop with a multiplying counter whose output goes to a multiplexer having a plurality of grounded capacitors connected thereto.

Abstract: A method and apparatus is described for implementing a real time video processing system based on the rationalized Haar transform. The system operates in real time to remove redundant information from video data for the purpose of compressing the video bandwidth. A digital apparatus for implementing the system is described which is capable of processing video in real time at data rates up to 60 M bits per second.

Abstract: A radiation carrier such as an optical glass fiber is embedded in a body of material such as a laminated composite panel with the free ends of the fiber extending to or beyond the edges of the structure so that radiation such as light can be directed through one end of the carrier and measured at the other end thereof, to monitor and detect the presence of moisture in the interior of the structure.

Abstract: Disclosed is apparatus and method for accurately determining the direction of true north or the change in drift of other gyroscopes. The apparatus comprises a single degree of freedom gyroscope driven by a permanent magnet electric motor. The gyroscope rotor is spun by the motor at varying speeds and the torque required to maintain the rotor at a null orientation is measured and recorded. The measured torques are processed to produce an accurate indication of true heading or to indicate the change in the level of drift of other gyroscopic instruments.

Abstract: A digital machine for detecting and processing pictorial edges in video data. The invention mechanizes, in parallel, three different processing techniques, the outputs of which are combined in a selectable manner to generate processed and enhanced video data. The first parallel processor convolves four inter-related 3.times.3-element masks with the 2-dimensional video input data to locate the pictorial edges, to determine the edge directions, to execute edge connectivity logic, and to calculate certain edge statistics. The second parallel processor implements a 3.times.3 element, low or high pass image filter, and an adaptive threshold filter. Both the first and the second parallel processors use Fast-Form algorithms which allow data processing in real time with a minimum of components. The third parallel processor operates on the video data in serial form to generate the video output from the edge processing unit.

Abstract: An inertial instrument including a multiplexed rebalance network and an associated plurality of inertial sensors and associated position signal generators, and torquers. The rebalance network includes a sampling network, a computing network, and a conversion and distribution network. The sampling network generates a succession of digital position words representative of a corresponding succession of sampled values for the position signals. The computing network successively transforms each of the digital position signals into digital rebalance loop compensation signals for the corresponding inertial sensor. The conversion and distribution network converts the digital rebalance loop compensation signals to rebalance torquer signals and applies those signals to the respective torquers.

Abstract: An eliminator of vaporized contaminants from gas in a closed system in which high pressure gas is subjected to a substantially adiabatic expansion with accompanying temperature drop at a point where the contaminants cannot cause problems. In the specific case of a gas bearing, contaminants which normally condense in the gap between bearing surfaces are caused to condense at points well removed from the bearing gap where they cannot cause failure of the gas bearing. A remotely located expansion chamber or zone is created and it may include a restricting orifice at the inlet to which gas pressure is relatively high and at the outlet of which pressure is significantly lower. The pressure drop is accompanied by a comparably large decrease in temperature to a point at which the vaporized contaminants condense. A filter may be included at or adjacent to the outlet to trap the condensed contaminants.

Abstract: A mechanism for positioning an aircraft rudder and brake pedal to accommodate the pilot. The present invention provides a means whereby aircraft rudder and brake cables adjustments are not disturbed when the assembly is repositioned anywhere within the adjustment range of the aircraft.

Abstract: An adaptive antenna system which enhances the desired signal in the output of the system while reducing the interference from signals arriving from directions other than that of the desired signal. The antenna system operates in conjunction with a modulation/demodulation system for spreading and despreading the spectrum of the desired signal. By a series of deterministic perturbations of phase shifters or other signal varying devices attached to the antenna elements, the system measures the effects of these perturbations: (1) on the wide-band energy in the output of the antenna, prior to spectrum despreading, and (2) on the narrow-band energy following despreading, and then adjusts the phase shifters or other signal varying devices so as to enhance the desired signal while reducing the interfering signals.

Abstract: A reduction in bandwidth of two-dimensional video data is obtained by the two-dimensional transformation of the video data by means of one of a class of fast transformations followed by the elimination of certain non-significant transform coefficients prior to the transmission of the transform data. The lower-order transform coefficients or "zonal coefficients" which are usually significant in size, are always transmitted. Prior to transmission, parity bits are added to the zonal coefficients to allow error detection. An adaptive filter eliminates from the higher-order transform coefficients, those non-significant transform coefficients of magnitude less than a threshold level, which level is adjusted in response to the amount of data in the buffer memory awaiting transmission so as to transmit the most significant transform coefficients from a succession of two-dimensional data vectors. At the receiving end of the communication link the array of transform coefficients is reconstituted from the received data.