Noise Or Unwanted Signal Reduction In Nonseismic Receiving System Patents (Class 367/901)
  • Patent number: 5245587
    Abstract: A multi-dimensional acoustic data processing and display system arranges acoustic data in a three-dimensional matrix. The three-dimensional matrix is compressed using singular value decomposition into singular vectors and singular values. A historical database is created and maintained and is also concatenated with the three-dimensional data. This database allows reverberation and noise to be diminished and other, weaker features in the data to be enhanced. Once the data is compressed, the data can be analyzed efficiently. The singular vectors are partitioned into one or more groups on the basis of their singular values or other criteria. Certain of the compressed data elements are enhanced or diminished by modifying the singular values within each of the groups of singular vectors. Selected singular vectors are processed further by other techniques for further enhancement, detection, isolation, feature extraction and classification.
    Type: Grant
    Filed: November 18, 1992
    Date of Patent: September 14, 1993
    Inventor: William H. Hutson
  • Patent number: 5245586
    Abstract: For suppressing reflections of an acoustic reception signal at a transmitting/receiving ultrasound transducer, the ultrasound transducer is connected to a compensation circuit which supplies the ultrasound transducer with a compensation transmission signal during reception, which has a waveform similar to the acoustic reception signal, but with a polarity opposite that of the acoustic reception signal. A summing stage is connected in a reception channel of the ultrasound transducer, the summing unit having a first input supplied with a compensated reception signal, formed by a combination of the acoustic reception signal and the compensation transmission signal. A second input of the summing unit is connected to the compensation circuit, which supplies a signal at the second input which removes the contribution made by the compensation transmission signal from the compensated reception signal, so that the output of the summing unit generates a reception signal devoided of the compensation transmission signal.
    Type: Grant
    Filed: October 30, 1992
    Date of Patent: September 14, 1993
    Assignee: Siemens Aktiengesellschaft
    Inventor: Dietrich Hassler
  • Patent number: 5228009
    Abstract: Signal processing apparatus and methods for elimination of undesirable clutter signals from desirable signals. This is performed without the use of filters by subtracting orthonormal basis functions from signal samples until the appropriate degree of clutter removal is achieved. Estimates of frequency information such as Doppler shifts due to fluid flow may thus be achieved with superior discrimination of true flow signals from sources of clutter or artifact, greater sensitivity to low flow rates, minimal computational effort and with fewer samples than the prior art.
    Type: Grant
    Filed: April 10, 1992
    Date of Patent: July 13, 1993
    Assignee: Diasonics, Inc.
    Inventors: Steven F. Forestieri, Ray S. Spratt
  • Patent number: 5226016
    Abstract: A method and apparatus are provided to adaptively form an optimum signal-free reference used to cancel near-field noise in an adaptive plate-noise cancellation system. First, second and third pressure sensors are positioned to detect any near-field plate-radiated noise. The first sensor is positioned closest to the plate, the third sensor is positioned furthest from the plate, and the second sensor is positioned between the first and third sensors. An acoustic far-field projector generates a plurality of broadband signals from a plurality of incidence angles. Each broadband signal is projected at an amplitude indicative of a noise-off condition. Outputs from the first and third sensors are combined to form a dipole responsive to each broadband signal). A feedback system is operatively associated with the dipole and the second sensor.
    Type: Grant
    Filed: April 16, 1992
    Date of Patent: July 6, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Russel A. Christman
  • Patent number: 5216640
    Abstract: An apparatus and method for detecting, processing, and tracking sonar sigs is provided. Plane wave energy from the sonar signal source is measured at multiple points using an array of plane wave energy receptors. These measurements are processed using an inverse beamformer to generate output beam levels. These output beam levels are then processed using the spectrum normalizer to yield spatially and spectrally normalized output beam levels. The normalized beam levels are then processed using an eight nearest-neighbor peak-picker to provide plane wave peaks. Finally, the plane wave peaks are processed by a three-dimensioned M of N tracker to identify peaks within a specified limit of frequency and angle change over time. The identified peaks may be displaced or recorded for further analysis.
    Type: Grant
    Filed: September 28, 1992
    Date of Patent: June 1, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: James Donald, Albert H. Nuttall, James H. Wilson
  • Patent number: 5208786
    Abstract: A system separates unknown signals which have been combined together through unknown linear filters and for which observations at multiple sensors are made. In a two channel circuit with two inputs and two sensors, the reconstructed source signals are assumed to be decorrelated such that the cross-correlation between the reconstructed source signals is near zero. The transfer functions which represent the crosstalk processes are estimated. The output signals are detected and the transfer functions are recursively solved. A reconstruction filter is used to recover the original input signals.
    Type: Grant
    Filed: August 28, 1991
    Date of Patent: May 4, 1993
    Assignee: Massachusetts Institute of Technology
    Inventors: Ehud Weinstein, Meir Feder, Alan V. Oppenheim
  • Patent number: 5187692
    Abstract: A plurality of acoustic transfer functions for a plurality of sets of different positions of a loudspeaker and a microphone in an acoustic system are measured by an acoustic transfer function measuring part. The plurality of measured acoustic transfer functions are used to estimate poles of the acoustic system by a pole estimation part, and a fixed AR filter is provided with the estimated poles as fixed values. A variable MA filter is connected in series to the fixed AR filter and the acoustic transfer function of the acoustic system is simulated by the two filters. The filter coefficients of the variable MA filter are modified with a change in the acoustic transfer function of the acoustic system.
    Type: Grant
    Filed: March 20, 1992
    Date of Patent: February 16, 1993
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Yoichi Haneda, Shoji Makino, Yutaka Kaneda
  • Patent number: 5184331
    Abstract: Transducer circuit, including a tuning inductor for removing the reactive mponent from the signal of an acoustic transducer; the inductance varies with frequency, thus permitting the transducer-tuning inductor to present a non-reactive load to the an amplifier over a broad operating frequency.
    Type: Grant
    Filed: June 1, 1992
    Date of Patent: February 2, 1993
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Michael J. Sullivan, Douglas G. Dussault
  • Patent number: 5177711
    Abstract: This switch device for detecting an object comprises a transducer for emitting and receiving ultrasonic signals to and from an object, a transmitter for driving the transducer, a receiver for receiving a signal from the transducer, a gate for detecting a short-distant object, a gate for detecting a long-distant object, and a circuit for setting the timings of the gates in accordance with the detecting ranges of the object.
    Type: Grant
    Filed: April 16, 1991
    Date of Patent: January 5, 1993
    Assignee: Omron Tateisi Electronics
    Inventors: Yukio Yamaguchi, Atsushi Kawano, Hideyuki Suzaki, Hiroshi Shimamoto
  • Patent number: 5164919
    Abstract: A sonar sensor comprising a substantially non-corrodible housing and a fluidic gainblock disposed therein. In addition, one or more fluid-filled laminar proportional amplifiers are arranged either in series or in parallel and contained within the fluidic gainblock. Means are provided to produce a jet within each laminar proportional amplifier, which is then modulated by incoming acoustic signals. The pressure caused by diverting the jet from its equilibrium path is proportional to, but greater than, the incoming acoustic signal. Hydrophones are used to convert the amplified acoustic signal into an electrical signal. In one embodiment, the fluidic gainblock is free-flooded and open to the liquid environment in which it is used, obviating the need for pressure equalization. In another embodiment, the fluidic gainblock is provided with filtering means for prevent the accumulation of sediment within the cavities making up the laminar proportional amplifiers.
    Type: Grant
    Filed: December 6, 1991
    Date of Patent: November 17, 1992
    Assignee: United States of America as represented by the Secretary of the Army
    Inventors: Michael Scanlon, Stephen M. Tenney, Nassy Srour, James W. Joyce
  • Patent number: 5144595
    Abstract: The adaptive statistical filter providing improved performance target mot analysis noise discrimination of the present invention includes a bank of parallel Kalman filters. Each filter estimates a statistic vector of specific order, which in the exemplary third order bank of filters of the preferred embodiment, respectively constitute coefficients of a constant, linear and quadratic fit. In addition, each filter provides a sum-of-squares residuals performance index. A sequential comparator is disclosed that performs a likelihood ratio test performed pairwise for a given model order and the next lowest, which indicates whether the tested model orders provide significant information above the next model order. The optimum model order is selected based on testing the highest model orders. A robust, unbiased estimate of minimal rank for information retention providing computational efficiency and improved performance noise discrimination is therewith accomplished.
    Type: Grant
    Filed: January 27, 1992
    Date of Patent: September 1, 1992
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Marcus L. Graham, Francis J. O'Brien
  • Patent number: 5136555
    Abstract: A novel totally integrated divers face mask and ultrasound underwater voice communication apparatus having integral transducer-transmit-receive-power source enclosures of low profile, flexible hands-free-voice or push-to-talk operation while submerged, and noise-cancelling microphone features for reducing bubble and vibration noise.
    Type: Grant
    Filed: July 5, 1991
    Date of Patent: August 4, 1992
    Assignee: Divecomm, Inc.
    Inventor: Ivan Gardos
  • Patent number: 5134591
    Abstract: A survival detection system distinguishes a low frequency survivor generated signal component from ambient low frequency signal components in a seismic sensor signal output. A twin-tee filter circuit a has its input coupled to the sensor signal output and it has a plurality of interconnected charging resistor and capacitor components with an output circuit coupled thereto to generate the detected survivor signal component.A CMOS switch is connected in each charging current path between the associated resistor and capacitor in such path to control the capacitor charging currents. A bandwidth control circuit applies an adjustable feedback voltage from filter output circuit to the twin-tee filter.A variable duty cycle generator controls the on-off duty cycle of the CMOS switches to control the effective charging current path resistance and thereby the capacitor charging currents and the tuned or center frequency of the filter.
    Type: Grant
    Filed: February 25, 1991
    Date of Patent: July 28, 1992
    Assignee: Westinghouse Electric Corp.
    Inventor: Jay S. Harmeling
  • Patent number: 5117401
    Abstract: An active adaptive noise canceller that inserts delays in the weight update logic of an adaptive filter employed by the canceller to make the filter stable. It has been found that there is a great deal of flexibility regarding the selection of the delay values. This insensitivity permits designing the delays in advance, and not having to adjust them to different situations as they change, thus no longer requiring a training mode. The canceller dramatically reduces the amount of hardward needed to perform active adaptive noise cancelling, and eliminates the need for the training mode, which in some applications, including automobiles, for example, can be as objectionable as the noise sources that are to be suppressed.
    Type: Grant
    Filed: August 16, 1990
    Date of Patent: May 26, 1992
    Assignee: Hughes Aircraft Company
    Inventor: Paul L. Feintuch
  • Patent number: 5103431
    Abstract: Apparatus for detecting sonar signals embedded in noise includes a neural network trained to detect signals in response to the slope of amplitude rank ordered noise corrected powers. A detector detects an analog waveform. Means samples and digitizes the analog waveform to obtain digital samples which in turn are passed through a cosine window. The digital samples are Fourier transformed into conjugate sets of complex numbers representing amplitude and phase. One conjugate set of the complex numbers are discarded, and the remaining complex numbers ranked according to frequency. The sum of the square of the real and imaginary component of each of the remaining complex numbers in a frequency band are provided to obtain a corresponding series of representing estimated power ranked by frequency over the band. The noise contained in subbands of the band is estimated.
    Type: Grant
    Filed: December 31, 1990
    Date of Patent: April 7, 1992
    Assignee: GTE Government Systems Corporation
    Inventors: David F. Freeman, William J. Fonseca
  • Patent number: 5089997
    Abstract: An ultrasonic energy detector advantageously supplies both frequency and amplitude information which is related to the ultrasonic frequency and the amplitude of the detected ultrasonic energy. Frequency division is employed to reduce the relatively broad range of ultrasonic frequencies into a narrower audio frequency range while still providing information useful to identify the ultrasonic energy by frequency detection. The effect of anticipated background noise at all levels of gain selected is eliminated by subtracting a signal representative of the anticipated background noise and proportional to the selected predetermined gain from the amplitude of the detected ultrasonic energy.
    Type: Grant
    Filed: November 2, 1990
    Date of Patent: February 18, 1992
    Assignee: Pasar, Inc.
    Inventor: Joseph P. Pecukonis
  • Patent number: 5077696
    Abstract: A floating sensor system is provided to detect very low frequency pressure ignals (down to 0.01 Hz). This system detects pressure fluctuations or pressure signals of interest in the ocean or other body of water in the presence of unwanted pressure signals generated by surface wave induced motion. A drifting sensor surface float follows the surface waves and in turn moves a suspended pressure sensor vertically, such that it detects the wave motion as a change in static pressure which then constitutes a noise source. A correlation circuit and a logic circuit discriminate between a first composite signal, comprised of the pressure signals of interest and wave motion noise, and a second reference signal, comprised only of the wave motion noise to provide an output signal transmitted to a monitoring station.
    Type: Grant
    Filed: December 27, 1990
    Date of Patent: December 31, 1991
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: James F. McEachern, Robert M. Balonis
  • Patent number: 5068834
    Abstract: The method and the device are designed to cause the signal of each hydrophone of an antenna to be rid of the component due to the vibrations of a wall close to which the antenna is placed. To this end, a correction signal is deducted from the signal of the hydrophone. This connection signal takes account of the vibrations of the wall measured by sensors placed on the wall, in the vicinity of the antenna. The study of the circuit which enables this correction signal to be given is done by resolving the vibration of the wall into its dominant modes of deformation.
    Type: Grant
    Filed: May 24, 1990
    Date of Patent: November 26, 1991
    Assignee: Thomson-CSF
    Inventor: Bernard Fromont
  • Patent number: 5063541
    Abstract: A beam former method and an apparatus therefor in an ultrasonic imaging system, in which switching of delay elements is performed by means of delay switches in a section in which no ultrasonic wave transmission/reception is performed and switching noise generated in this section is stored as a noise signal into a memory. The stored noise signal is subtracted from a reception signal which is obtained through ultrasonic wave transmission/reception and which contains switching noise superimposed thereon to thereby obtain a reception signal from which the noise has been eliminated.
    Type: Grant
    Filed: March 29, 1990
    Date of Patent: November 5, 1991
    Assignee: Hitachi Medical Corp.
    Inventors: Shin-ichi Kondo, Kageyoshi Katakura, Hiroshi Ikeda
  • Patent number: 5056068
    Abstract: For detecting a quickly or sharply varying signal (the event) against a background of a more slowly changing ambient signal (the background), the envelope detector inputs the signal and full wave rectifies it. It sends the signal to the background filter and event filter, each of which includes an RC circuit. The background filter and event filter each independently process the signal to be evaluated in different manners based on the intrinsic frequency characteristics of the event signal, and of the background signal. The outputs of the two filter sections are sent to the decision section. Based on its processing, the decision section outputs a signal in one of two states, one corresponding to detection, and the other corresponding to non-detection.
    Type: Grant
    Filed: February 5, 1990
    Date of Patent: October 8, 1991
    Assignee: Accu-Sport International, Inc.
    Inventor: Ralph W. Barnes
  • Patent number: 5043954
    Abstract: An apparatus for preventing a direct turning-in of the supersonic wave from the opening of the sender to the opening of the receiver in a supersonic wave device for a vehicle in which an object placed near the vehicle body id detected by the supersonic wave. A cylindrical turning-in preventive member made of foamed material having discrete bubbles is arranged at the opening of the sender or the receiver.
    Type: Grant
    Filed: April 17, 1989
    Date of Patent: August 27, 1991
    Assignee: Niles Parts Co., Ltd.
    Inventors: Seiei Takeoka, Masami Ebihara
  • Patent number: 5040156
    Abstract: Acoustic sensor device with noise suppression, in particular for sensors arranged on a noise-generating aggregate, using a double sensor (M1, M2) located between a noise source (S) and an object emitting the sound to be picked up, one of the sensors (M1) being directed towards the noise source (S) and supplying to a control circuit (R) a noise signal which controls an anti-noise source (A) in such a way that it generates an anti-phase sound p.sub.A for compensating the noise p.sub.S, the other sensor (M2) being directed toward the object to be measured and supplying a measuring signal in which the noise fraction is highly weakened and the useful sound fraction is barely weakened, so that the acquisition range of the sensor (M2) is extended as a result of this reduction of sound fractions as a function of the direction of arrival.
    Type: Grant
    Filed: June 29, 1990
    Date of Patent: August 13, 1991
    Assignee: Battelle-Institut e.V.
    Inventor: Dieter Foller
  • Patent number: 5038328
    Abstract: An active, relatively high gain, low power consuming band pass filter circuit centered at approximately 6 KHZ and having a pass band of 100-200 HZ. In a disclosed glass breakage sensor, the filter couples sensed ambient sounds of breaking glass to associated detection, driver and annunciator means. Signals of appropriate duration and frequencies indicative of breaking glass are thereby monitorable to define and induce an alarm condition within a security system.
    Type: Grant
    Filed: June 27, 1990
    Date of Patent: August 6, 1991
    Assignee: Interactive Technologies, Inc.
    Inventor: Robert E. Brunius
  • Patent number: 5008862
    Abstract: A switch device is disclosed for detecting an object which comprises a transducer for emitting and receiving ultrasonic signals to and from an object, a transmitter for driving the transducer, a receiver for receiving a signal from the transducer, a gate for detecting a short-distant object, a gate for detecting a long-distant object, and a circuit for setting the timings of the gates in accordance with the detecting ranges of the object.
    Type: Grant
    Filed: January 18, 1990
    Date of Patent: April 16, 1991
    Assignee: Omron Tateisi Electronics Co.
    Inventors: Hiroshi Shimamoto, Hideyuki Suzaki, Yukio Yamaguchi, Atsushi Kawano
  • Patent number: 4992998
    Abstract: In acoustic level sensing apparatus, in which pulses of acoustic energy are transmitted by an electrically energized transducer towards a surface to be sensed, and the electrical output from the transducer following the pulse is digitized and analyzed to detect a return echo from the surface, so as to produce a digitized echo profile. The digitzed echo profile is enhanced by removing narrow peaks likely to correspond with certain types of spurious echo, and narrow valleys which may represent fragmentation of a wanted echo. Echoes are identified by comparing the profile with a time varying threshold generated derived from a linear regression performed on part of the threshold, various different types of comparison being performed and their results combined prior to selecting the most likely true echo on the basis of the combined results.
    Type: Grant
    Filed: September 12, 1989
    Date of Patent: February 12, 1991
    Assignee: Federal Industries Industrial Group Inc.
    Inventor: Steven J. Woodward
  • Patent number: 4974214
    Abstract: A method for suppressing interference signals during operation of ultrasonic proximity transducers suppresses the interference signals that are generated by continuous noises. Repeated ultrasonic pulses are transmitted from an ultrasonic proximity transducer, and the received signals are scanned. The scanned values of the received signal are converted into digital values. After storage, the digital values are compared with a step function having one or more step sections of constant value serving as a time-dependent interference noise threshold so that the usable echo signal can be determined and separated from the interference signals. With further evaluation, the echo transit time of the usable echo signal is determined and provided to a control and evaluation unit. By suppressing continuous noises, and further suppressing stochastic interference signals, the usable echo signal is reliably filtered from a reception signal that is overlaid with interference signals.
    Type: Grant
    Filed: November 13, 1989
    Date of Patent: November 27, 1990
    Assignee: Siemens Aktiengesellschaft
    Inventors: Alfred Forster, Gerd Schorner
  • Patent number: 4955000
    Abstract: An ultrasonic system for identifying the location of personnel within a multiple room complex. The system includes ultrasonic transmitters adapted to be transported by the personnel. The transmitters periodically transmit pulse code modulated (PCM) transmitter signals representative of a digital code sequence characteristic of the person, and formed by a plurality of bit positions which are separated from adjacent bit positions by predetermined time intervals. Ultrasonic receivers for receiving the transmitter signals are positioned within each room of the complex. The receivers detect bits of the code sequence only during window periods corresponding to expected bit positions. Detected code sequences are compared to predetermined code sequences, and receiver signals are produced as a function of the comparison. A central station is coupled to receive the receiver signals, and provides a visual indication of the rooms in which the persons transporting the transmitters are located.
    Type: Grant
    Filed: June 16, 1989
    Date of Patent: September 4, 1990
    Assignee: NAC Engineering and Marketing, Inc.
    Inventor: Harvey J. Nastrom
  • Patent number: 4953145
    Abstract: An active phase quieting target highlight detector using phase and magnitude detection. In contrast to classical magnitude-only detection schemes, the present invention, by combining phase detection, can discriminate sets of spatially-ordered highlights due to a target, from clutter or multipath echoes, along with nonsmoothed magnitude or envelope detection, that can better discriminate target structure due to reception of echoes from shorter active pulses. False target detection and multipath detection are reduced while detection or target structure is retained by the time domain detection scheme of the invention.
    Type: Grant
    Filed: September 30, 1988
    Date of Patent: August 28, 1990
    Assignee: Honeywell Inc.
    Inventor: Gerrard M. Carlson
  • Patent number: 4951269
    Abstract: An echo canceller in a system, having a long impulse response such as in an acoustic system, which employs a fast Fourier transform to transform input data represented in the time domain into signals represented in the frequency domain to reduce calculations. To solve the problem of a long delay, the impulse response length is divided into a plurality of blocks. Each block then has a decreased number of samples within each block. Thus, a fast Fourier transform and finite impulse response type digital filtering are effected, so that the processing delay is decreased while the amount of calculations is kept small.
    Type: Grant
    Filed: June 24, 1988
    Date of Patent: August 21, 1990
    Assignee: Fujitsu Limited
    Inventors: Fumio Amano, Mohammad R. Asharif, Shigeyuki Unagami, Yoshihiro Sakai
  • Patent number: 4947177
    Abstract: A narrow band noise cancellor and signal correllator which obtains an increased signal to noise ratio of a received signal from a multi sensor array; the resulting output signal is at double the input frequency. A pair of narrow band similar input signals are added, and subtracted, and the resulting signals are multiplied together. The positive and negative product terms of the signal are separated and the positive term inverted, and the resulting separated signals are individually added with the squared representation of one of the input signals. The resulting added signals are summed and the sum is passed through a narrow band filter having its center frequency at double the input frequency.
    Type: Grant
    Filed: October 6, 1978
    Date of Patent: August 7, 1990
    Assignee: Her Majesty the Queen in right of Canada, as represented by the Minister of National Defence of Her Majesty's Canadian Government
    Inventor: Noel O. Fothergill
  • Patent number: 4933914
    Abstract: A channel adaptive active sonar is disclosed, wherein the sonar transmit waveform is adaptively selected in accordance with the measured sonar channel scattering function to reduce the response of the sonar to unwanted reverberation while preserving the response to signal returns. As a result, the sonar target detectability is improved over sonar systems which do not adapt to the variable properties of the ocean channel. The sonar is operable in two modes, the channel measurement mode and the normal active mode. In the channel measurement mode, probe signals are transmitted to test the channel response. From the sonar receive signals resulting from the transmitted probe signals, the channel scattering function is estimated. The transmit waveform for the sonar active mode is then designed to provide a waveform whose ambiguity function overlaps minimally with the estimated channel scattering function.
    Type: Grant
    Filed: January 15, 1987
    Date of Patent: June 12, 1990
    Assignee: Hughes Aircraft Company
    Inventors: Paul L. Feintuch, Francis A. Reed
  • Patent number: 4928264
    Abstract: A hydrophone mounted on the hull of a ship comprises an electromechanical ansducer made of void-containing ceramic material having a high piezoelectric sensitivity to water-borne acoustic sound signals, a transducer made of solid ceramic material having a low piezoelectric sensitivity to hydrostatic acoustic signals, both transducers having similar piezoelectric sensitivity to shipboard noise transmitted via the ship's hull and transducer mounting; and means for sensing and manipulating voltage signals generated in response to water-borne acoustic signals and mount-transmitted shipboard noise such that the mount transmitted noise signals are largely cancelled out and a relatively noise-free signal representing hydrostatically transmitted sound is obtained.
    Type: Grant
    Filed: June 30, 1989
    Date of Patent: May 22, 1990
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Manfred Kahn
  • Patent number: 4918671
    Abstract: A system is provided for the detection of an unsuitable water condition in which either large globules of solid material or bait fish suspended in the water beneath a vessel adjacent the hull of the vessel are detected and the associated depth sounding device is inhibited from providing a depth output. This eliminates the display or annunciation of erratic depth data, or the use of erratic data for closed or open loop control systems. In one embodiment, the unsuitable water condition is sensed through the detection of returns in a short water column adjacent the hull. In a further embodiment, returns from the water column coupled with receiver gain being open above a predetermined threshold provide the indication of the presence of the unsuitable water condition.
    Type: Grant
    Filed: April 5, 1989
    Date of Patent: April 17, 1990
    Inventor: Robert K. Tendler
  • Patent number: 4915498
    Abstract: A sensor for creating images containing range depth information is disclosed. The sensor comprises a gated energy transmitter used to "illuminate" the object to be imaged, a gated integrating imaging energy receiver to produce "raw" images, a processor system to combine the raw images from the receiver to produce a output image, and a timing system to control the gate timing of the transmitter and gate timing of the receiver. In operation, two raw images are created with differing time relationships between the transmitter gating, receiver gating and integrated energy readout. One raw image is a reference image containing no range information while the second image contains range information along with unwanted information such as reflectivity variations. These raw images are processed to produce a final output image in which the unwanted information is mainly cancelled producing an output "range" image. This output image is a one or two dimensional array of data.
    Type: Grant
    Filed: April 19, 1988
    Date of Patent: April 10, 1990
    Inventor: Joseph H. Malek
  • Patent number: 4914640
    Abstract: In combination with any signal processor system which uses an R-C integra type energy detector to recognize the presence of electrical signals such as those that are proportional to a received acoustic ping signal, the turnaround time stability improvement comprising a timing initiation signal recognition means, a validation means, first and second one-shorts for A/D conversion, and AND gate means for receiving the timing initiation signal and the validation signal and outputting a valid ping timing signal only when both are true, said valid ping timing signal in turn causing subsequent actions normally initiated by this event to occur, such as a transponder system incorporation the present invention projecting a return ping into the water.
    Type: Grant
    Filed: February 3, 1989
    Date of Patent: April 3, 1990
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Victor A. Andersen
  • Patent number: 4910363
    Abstract: There is provided a coordinates input apparatus comprising: a vibrator drive controller to output a vibrator drive signal obtained by synthesizing a plurality of pulse trains whose phases differ; a vibration pen to generate a vibration from a vibrator which generates the vibration in response to the vibration drive signal output from the vibrator drive controller; a vibration propagating plate made of a transparent acrylic or glass plate to propagate the vibration generated by the vibration pen; a plurality of vibration sensors, attached to the vibration propagating plate, for detecting the vibration generated by the vibration pen at a plurality of positions; and a coordinate value calculation/control circuit for calculating the vibration propagating times from the vibrations detected by the vibration sensors at a plurality of positions, thereby obtaining the coordinate values on the vibration propagating plate on which the vibration pen is located from the propagating times calculated.
    Type: Grant
    Filed: July 10, 1989
    Date of Patent: March 20, 1990
    Assignee: Canon Kabushiki Kaisha
    Inventors: Katsuyuki Kobayashi, Kiyoshi Kaneko
  • Patent number: 4903247
    Abstract: A digital echo canceller [1] with a good protection against double-talk comprises a first filter [9] for the echo cancellation proper, a second adaptive filter [11] for making continuously adapted filter coefficients available to the first filter [9] and gate means [15] which will only apply the adapted filter coefficients to the first filter [9] if certain conditions are satisfied. In the echo canceller [1] a specific filter combination is used, in which the first filter [9] is a time-domain programmable filter (TDPF) and the second filter [11] is a frequency-domain block-adaptive (FDAF), and further means [20,20(1)] are provided that are arranged in cascade with the gate means [15] for transforming the frequency-domain filter coefficients [W(p;m)] of the FDAF [11] into time-domain filter coefficients [w(i;m)] for the TDPF [9].
    Type: Grant
    Filed: June 23, 1988
    Date of Patent: February 20, 1990
    Assignee: U.S. Philips Corporation
    Inventors: Petrus J. Van Gerwen, Franciscus A. M. van de Laar, Hendrik J. Kotmans
  • Patent number: 4894808
    Abstract: The level of signal noise caused by fluid flow at a pressure transducer, such as a hydrophone or geophone, is determined by measuring the electric field induced when the fluid flow through a magnetic field. The electric field, which is proportional to flow rate, is measured by electrodes positioned about the transducer. The pressure due to the flow is derived from the flow rate voltage by a digital filter which may be adaptive, to allow for varying flow conditions, or which may employ a predetermined electric field/flow noise relation. This flow noise is then subtracted from the received signal, the resultant signal then being substantially noise free.
    Type: Grant
    Filed: May 31, 1989
    Date of Patent: January 16, 1990
    Assignee: The Marconi Company Limited
    Inventors: Mark Pedley, William J. Fitzgerald
  • Patent number: 4890266
    Abstract: In acoustic level sensing apparatus, in which pulses of acoustic energy are transmitted by an electrically energized transducer towards a surface to be sensed, and the electrical output from the transducer following the pulse is digitized and analyzed to detect a return echo from the surface, so as to produce a digitized echo profile. The digitized echo profile is enhanced by removing narrow peaks likely to correspond with certain types of spurious echo, and narrow valleys which may represent fragmentation of a wanted echo. Echoes are identified by comparing the profile with a time varying threshold generated derived from a linear regression performed on part of the threshold, various different types of comparison being performed and their results combined prior to selecting the most likely true echo on the basis of the combined results.
    Type: Grant
    Filed: May 5, 1988
    Date of Patent: December 26, 1989
    Assignee: Federal Industries Industrial Group Inc.
    Inventor: Steven J. Woodward
  • Patent number: 4872145
    Abstract: A noise trap circuit particularly suitable for use in an electro-acoustic system, operates to suppress low level signals or noise while allowing a relatively large signal to pass unattenuated between input and output terminals of the circuit. Blocking elements between the input and output terminals establish a high impedance path to the noise but switch to a conductive state when the large signals are present at the input terminals. Shunt elements across the output terminals provide a low resistance path or "crowbar" when only the noise is present at the input terminals, but switch to a non-conductive state when the large signals are sensed at the circuit input.
    Type: Grant
    Filed: May 4, 1987
    Date of Patent: October 3, 1989
    Assignee: Hazeltine Corporation
    Inventors: James A. Culbert, Daniel M. Seslar
  • Patent number: 4848924
    Abstract: An apparatus and method for measuring high temperatures in a boiler transmits pulses of acoustic waves, from one side wall of the boiler to an opposite side wall thereof. Acoustic noise within the boiler, as well as the transmitted pulses of acoustic waves are received at the opposite side of the boiler. The received signal is digitized and compared to a digitized sample of the pulses during a time period which is more than the maximum transit time for the pulses between the side walls. A point of maximum correlation between the sample and the signal is taken as the arrival time for the pulse and is used to calculate the transit time of the pulse across the boiler. This transit time is used in turn to calculate the velocity of the pulses. The temperature can then be calculated as a function of the velocity, the molecular weight of the medium and the specific heat ratio of the medium. Each pulse has a modulated frequency between 500 and 3,000 Hz.
    Type: Grant
    Filed: August 19, 1987
    Date of Patent: July 18, 1989
    Assignee: The Babcock & Wilcox Company
    Inventors: Steven P. Nuspl, Edmund P. Szmania, John A. Kleppe, Peter R. Norton
  • Patent number: 4796238
    Abstract: System to measure the coefficients of reflection of submerged surfaces such as the seabed, by comparison of the intensities of acoustic impulses propagated between a source and a receptor, both of which are submerged, and that of the echoes of these impulses on the reflectors. For this purpose, there is provided a programmed calculator, an interface card to communicate with different units: an echo-sounder, a source triggering detector, a shot box to control the source and a recorder, a programmable attenuator, an acquisition card driven by the calculator and bearing an adjustable type filter and a circuit, also controlled by the calculator, for modifying the functioning parameters of the attenuation and of the filter, and fixing the starting parameters.
    Type: Grant
    Filed: August 29, 1986
    Date of Patent: January 3, 1989
    Assignee: Institut Francais du Petrole
    Inventors: Aline Bourgeois, Jean-Claude Bourgeois
  • Patent number: 4750584
    Abstract: A distance detecting device having a transmitter for intermittently transmitting measuring waves toward an object, a pair of receivers provided so as to be spaced from each other by half the wave length of the waves in a direction of the object, each receiver receiving reflected waves from the object and transmitting a reception signal responsive to the amplitude of the reflected waves, an addition circuit for adding the reception signal from each of the pair of receivers and transmitting an addition signal, a peak detection circuit for detecting a peak of the addition signal and transmitting a reflected waves reach signal at the time of peak detection, and an operation device for calculating the distance to the object based on the return time from the time when the waves are transmitted to the time when the reflected waves reach signal is outputted.
    Type: Grant
    Filed: January 17, 1986
    Date of Patent: June 14, 1988
    Assignee: Nippon Soken, Inc.
    Inventors: Hiroaki Tanaka, Shigeyuki Akita, Hideki Kashiwagi
  • Patent number: 4730282
    Abstract: A method for locating signal sources, particularly sound signal sources, is suggested using several spacially separated sensors whose output signals are processed in order to detect noise and to eliminate such noise under utilization of a normalizing factor, the normalizing factor considers particularly those frequencies which, for one reason or another, are uniquely attributable to noise.
    Type: Grant
    Filed: February 11, 1985
    Date of Patent: March 8, 1988
    Assignee: MBB GmbH
    Inventors: Reinhard Jaeger, Peter von Volckamer
  • Patent number: 4719606
    Abstract: A process and device for passive detection of helicopters includes detection of helicopter noise and ambient noise by means of an electro-acoustic transducer, and outputting of an amplitude modulated signal therefrom; amplitude demodulation of the signal in the frequency band between 300 Hz and 3500 Hz; spectral analysis of the demodulated signal; and selection and registration of characteristic frequency lines reflective of the rotary units of the helicopter. The process and device permit passive detection of helicopters in the lower noise, higher frequency band, thereby also permitting utilization of smaller antenna arrays.
    Type: Grant
    Filed: March 14, 1985
    Date of Patent: January 12, 1988
    Assignee: Etat Francais
    Inventor: Michel B. Andrieu
  • Patent number: 4594695
    Abstract: A method and device for attenuating wideband spurious noises to improve the signal-to-noise ratio of a tracked acoustic signal. Two sensors (1 and 2) are provided, one of which receives the disturbed tracked signal and the other the spurious noises, to feed a plurality of correlation modules (4) via as many spectrum-line filters (3) distributed throughout the useful bandwidth of sensor (1), each of said correlation modules (4) supplying a correction signal and the sum of said correction signals being subtracted from the signal given by sensor (1) to yield a noise-free tracked signal. The invention is applicable to acoustic reception systems used in noisy environments.
    Type: Grant
    Filed: September 9, 1983
    Date of Patent: June 10, 1986
    Assignee: Thomson-CSF
    Inventors: Michel Garconnat, Philippe Morgand
  • Patent number: 4590593
    Abstract: An electronic noise filtration system for use in improving the signal to noise ratio of acoustic data transmitted from a downhole transducer in a measurement while drilling system. Signals from a pair of receiving acoustic transducers located in the mud flow path directed downhole are input to a differencing amplifier. The RMS output of the amplifier is converted from an analog to a digital signal and then processed by a computer programmed with a least mean squares technique for minimizing the signal. The input from one receiving transducer is routed through a delay line wherein a programmable clock controls the timing of the signal delay. The delay time is controlled and adjusted by the computer's calculation of the frequency with which the clock should drive the delay line to minimize the difference between the two received transducer signals. This function minimizes ambient noise in the acoustic transmission line formed by the column of drilling fluids when no data transmissions are being made.
    Type: Grant
    Filed: June 30, 1983
    Date of Patent: May 20, 1986
    Assignee: NL Industries, Inc.
    Inventor: Paul F. Rodney
  • Patent number: 4530076
    Abstract: Apparatus and method for discriminating against non-Gaussian noise. Analog signals from an array of sensors are converted to real and imaginary digital representations and processed such that non-Gaussian noise is separated from signals of interest. The processor uses estimates of Kurtosis and quantiles from either past or adjacent frequency components to construct non-linear elements, which are then used to process remaining signal data to improve the signal-to-noise ratio thereof by removing non-Gaussian noise therefrom.
    Type: Grant
    Filed: June 28, 1983
    Date of Patent: July 16, 1985
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Roger F. Dwyer
  • Patent number: 4463452
    Abstract: A modulation/signal processing technique for acoustic communication in show water. Digital information is transmitted in a time expended version of frequency shift keying where a tone burst at a first frequency represents a logical zero and a tone burst at a second frequency represents a logical one. There is a long quiet time between bits to allow multipath interference to decay. A relative energy detector with a fast attack/slow decay circuit for Doppler compensation is used to receive the transmitted tone bursts and reproduce a digital data train equivalent to the transmitted pulse train. A single communication channel employs two frequencies to transmit an identity code as a signal validating and identification method and two frequencies to simultaneously transmit telemetry data.
    Type: Grant
    Filed: September 13, 1982
    Date of Patent: July 31, 1984
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Jay V. Chase, Jr.
  • Patent number: 4417313
    Abstract: A method for optimizing the design of finite noise barriers by using an extension of the Biot-Tolstoy rigorous closed form impulse solution for diffraction of an acoustic pressure pulse by an infinite rigid wedge. An initial finite barrier is defined and then a calculation made of the impulse signal transmitted on one side of the barrier and received on the other side by adapting the Biot-Tolstoy solution to a digital computer. The integrals of the acoustic pressure impulse are calculated for each source/receiver path for each segment of the barrier. The integrals are then compared and the segments are adjusted and new calculations made until all integral contributions are equal. The integrals are then digitally Fourier transformed to determine attenuation at the desired frequencies. After comparison with the desired attenuation, all segments are proportionately adjusted and the entire computational process reiterated until the optimal attenuation is achieved.
    Type: Grant
    Filed: May 18, 1981
    Date of Patent: November 22, 1983
    Inventor: Herman Medwin