Abstract: An underwater detection apparatus for detecting a target by transmitting and receiving an ultrasound signal is provided. The apparatus includes a replica memory module for storing the typical amplitude evolution of a seawall echo during a predetermined time period as a template-replica beforehand, a correlator module for determining a correlation between the amplitude evolution of an echo signal reflected from the target and the template-replica, a seawall detector module for detecting a seawall position based on the correlation, and a seawall display processor module for displaying the seawall on its position in an indicator.

Abstract: A ranging apparatus includes a reference pulse generator generating a reference pulse having a first frequency at a first point in time of transmitting a ranging signal from a first device; a delay pulse generator generating a delay pulse signal having a second frequency at a second point in time of receiving the a response signal transmitted from the second device in response to the ranging signal; an overlap detector detecting a third point in time that the reference and delay pulses overlap each other; a counter counting one of the reference and delay pulses until the third point; and a distance calculator calculating an amount of time from the first point to the second point by applying the first and second frequencies, and a count value of the counter and calculating the distance between the first device and the second device by using the amount of time.

Abstract: Dynamic positioning of a vessel 10 connected to the seafloor 14 by a riser 12 utilizes a measurement of riser 12 bottom angle combined with a measurement of vessel 10 velocity, optionally obtained from a Doppler log 16. These two signals are combined to produce a single position estimate using an algorithm such as a Kalman filter. Using riser bottom angle only would result in an unstable control system, since the bottom angle lags the vessel motion by a considerable amount and the relationship is non-linear. Using the velocity measurement alone would result in a slow drift of position. The combination of the two eliminates the disadvantages of the individual measurements.

Abstract: A method for creating jamming within an area and a jamming arrangement. The arrangement includes a plurality of distributed jammers. The jammers include a transmitter, receiver and logic unit and communication is established with the jammers. Communication is established directly between jammers included in the arrangement and information that is to be transmitted from one jammer to the other jammers is transmitted by superposing the information on the jamming signal that is produced by the jammers. An autonomous distributed arrangement is achieved that is difficult to disable and that can be made relatively simple, reliable and cost-effective.

Abstract: A method for determining the depth of a parking space using at least one ultrasonic vehicle sensor. According to the method, the following steps are carried out as the vehicle drives longitudinally past the parking space: a) an ultrasonic wave is emitted, b) echo signals of the emitted ultrasonic wave are collected within a measuring window, c) the dispersion is determined and/or the distribution of the echo signals within that dispersion is determined, d) a depth is defined if the dispersion range of all and/or several echo signals that form a concentration within the distribution lies below a pre-determinable threshold value.

Abstract: A radar system comprises a transmitter that transmits a predetermined wideband signal, a digital receiver that records a returned signal using a one-bit ADC, a random noise source that is added to the transmitted or returned signal, a processing means where the received signal is distorted to compensate for the effect of the noise on the receiver. The predetermined wideband signal may be a pseudo random noise signal. The processing may include averaging prior to cross-correlation.

Abstract: The present invention is a method for providing hazard alerting for an aircraft via an airborne weather radar system. The method includes performing multiple weather radar scans at various tilt angles via the system and receiving radar returns via a receiver. The returns are stored in a memory of the system and merged with ground clutter suppression algorithms for eliminating ground returns from the stored returns and for creating a weather image based on remaining returns included in the stored returns. The image is provided via a weather radar display of the system, and includes an alert icon and an alert message when a hazard is present within an area proximal to the aircraft and is at or above a severity level threshold. The alert icon and alert message collectively indicate a type, severity level and location of the hazard in azimuth relative to a heading of the aircraft.

Abstract: A receiving part receives, over a plurality of pulse reception sections, the echo of a transmitted pulse in a first range cell after a lapse of a first time period from a pulse transmission, and outputs a first signal based on the received echo. The receiving part also receives, over a plurality of pulse reception sections, the echo of the transmitted pulse in a second range cell after a lapse of a second time period from the pulse transmission, and outputs a second signal based on the received echo. A signal integrating part integrates a first number of first signals and outputs an integration result as a first range integration signal. The signal integrating part also integrates a second number of second signals and outputs an integration result as a second range integration signal. A target detecting part detects, based on the first and second range integration signals, a target.

Abstract: A method for achieving omnidirectional transmission using of a towed linear antenna of length L greater than the wavelength ? of the signal transmitted. The antenna has a plurality of P projectors. The spacing between projectors is substantially less than ?/2. The method includes applying, to each projector, a transmit signal coming from a common transmit signal. The common signal is assigned a delay based upon a calculation that includes a non-linear term as a function of the position of the projector in the antenna, thereby allowing the angular aperture of the transmission pattern to be modulated. the method permits sonar detection systems comprising transmit and receive antennas having substantially identical diameters, which thereby can be reeled onto the same winch without it being necessary to separate them.

Abstract: A distance measuring system comprising: a transmitter that simultaneously emits an infrared radiation and an ultrasonic wave; and a receiver that include a table showing a relationship between an arrival time, indicative of a period from detection of the received infrared radiation to detection of the received ultrasonic wave, and a required received signal strength of the ultrasonic wave corresponding to the arrival time when the ultrasonic wave is directly received, that compares the received signal strength of the ultrasonic wave with a required received signal strength corresponding to the arrival time retrieved from the table, and that calculates the distance to the transmitter based on the arrival time when the received signal strength of the ultrasonic wave is higher than the required received signal strength corresponding to the arrival time retrieved from the table.

Abstract: The initial detection of a signal of interest in a data stream involves transmitting a signal received by a sonar or a radar to signal detection equipment wherein a signal of interest is characterized by a state model x(t) with values in a finite set {x1, . . . , xN}, to which there corresponds a finite set {?1, . . . , ?N} of N values of an observation variable ?, characteristic of this signal. To detect the signal of interest a detection criterion ?n(t) is simultaneously calculated in two different ways. The larger of the two calculated values is assigned to the criterion of ?n(t) which is then compared with a detection threshold.

Abstract: Method for locating an impact on a surface (9), in which acoustic sensors (6) pick up acoustic signals ski (t) generated by the impact and the impact is located by calculating, for a number of reference points of index j, a validation parameter representative of a function: PRODkji1i2. . . i2P(?)=?Ski1(?) ?Rji1(?)*?Ski2(?)*?Rji2(?) . . . ?Ski2p(?)*?Rji2p(?) where: ?Ski(?) and ?Rji(?)* are complex phases of Ski(?) and of Rji(?), for i=i1, i2, . . . , i2p, indices denoting sensors, Ski(?) and Rji(?) being the Fourier transform of ski(t) and rji(t), rji(t) being a reference signal corresponding to the sensor i for an impact at the reference point j, p being a non-zero integer no greater than NSENS/2.

Abstract: Sampling of a captured signal is synchronized to a tonal which may be unstable in frequency detected in the signal to cause it and all of its harmonics, sub-harmonics and fundamental to appear to have a substantially constant frequency relative to the sampling rate even if some related signals are otherwise undetectable amid noise. By adjusting an integration period of a fast Fourier transform to extract an intrinsic bandwidth, substantial signal processing gain can be obtained for the tonal and harmonically related signals, even if otherwise undetectable. Signal processing may be performed in either the time domain or the frequency domain. Recursive processing is performed to observe unrelated tones by grouping of tones which are harmonically related and supports detection of relationships between acoustic signal sources.

Abstract: A system applicable to acoustic, seismic, electromagnetic, hydrodynamic, and shock waves utilizing a map between signal time series and signal vectors defining the mathematical wave field model characterizing the signal's wave field. This map is developed from wave models relating field values to those on surfaces and corresponding uniqueness theorems. The system should allow for improved resolving power in bearing and elevation for discrimination of sources; detection and direction finding for signals below the average background level; detection based upon resolving power and signal vector characteristics rather than signal to noise ratio; reconstruction of signals of resolved sources for their transmitted information content; and multiple modes of operation. Adaptive incorporation of known undesired signals into the noise background and/or treatment of asymmetric background noise fields is permitted through use of a noise metric-based map yielding signal direction in the presence of diffraction effects.

Abstract: A matched-field based sonar system and method of use that supports real-time, three-dimensional acoustic source localization using a mobile, horizontal array. The system receives and processes acoustic array, non-acoustic array, and own-ship navigational data in the matched-field process (MFP). Driven by own-ship and array status, a global bathymetry database and an acoustic environmental model are used to generate replicas for the MFP. If a three-dimensional tracker is assigned, then the tracker will steer the search region to maintain contact on the target of interest. Displays are provided to the user including tracker displays (which provide tracker information), MFP ambiguity surface displays (which support contact localization), and non-acoustic and navigational displays. A control interface allows a user to control the search region in bearing, range, depth, and frequency; assign the three-dimensional tracker function; and control display processing.

Abstract: A radar level gauge system, for determining a filling level of a product contained in a tank, the radar level gauge system comprising: a transceiver for generating, transmitting and receiving electromagnetic signals; a probe electrically connected to the transceiver at a probe-transceiver connection and arranged to extend towards and into the product contained in the tank, for guiding a transmitted signal from the transceiver towards a surface of the product, and for returning a surface echo signal resulting from reflection of the transmitted signal at the surface back towards the transceiver; an impedance matching device arranged to extend along a portion of the probe inside the tank, an extension of the impedance matching device, in a direction perpendicular to the probe, decreasing along the portion of the probe with increasing distance from the probe-transceiver connection, to thereby provide impedance matching between an impedance of the probe-transceiver connection and an impedance of the probe; and pro

Abstract: In a pulse radar system where received echo pulses are expanded in time by multiplication with sampling pulses and subsequent integration, the effect of disturbances on the integration is reduced by using a sample and hold circuit having a switch and a hold capacitor and wherein the switch is closed only when a sampling pulse is applied for the multiplication.

Abstract: A hybrid drive (HD) multi-mode pipe projector (MMPP) for use in underwater acoustic applications is provided. The HD MMPP is formed with an inner magnetostrictive drive motor nested within an outer drive motor. The inner motor is surrounded by a magnetic field generating coil winding. Preferably the inner drive motor is a Terfenol-D motor and the outer drive motor is a radially-poled piezoceramic drive motor. This nested configuration provides increased bandwidth and low-frequency extension to the MMPP design.

Abstract: A particle motion sensor, includes: a sensing element capable of sensing a particle motion vector from a change in position thereof, and a packing material in which the sensing element is positioned, wherein the particle motion sensor is symmetric about its longitudinal axis and has a center of gravity coincident with its volumetric center. An apparatus includes a streamer; a plurality of acoustic sensors distributed along the streamer; and a plurality of particle motion sensors distributed along the streamer, at least one particle motion sensor being symmetric about its longitudinal axis and having a center of gravity coincident with its volumetric center.

Abstract: An apparatus having an array plate and an isolation section joined to the perimetrical edge of the plate. The isolation section has a plurality of isolation layers and a plurality of intermediate layers alternately arranged wherein an intermediate layer is positioned between consecutive isolation layers. An innermost isolation layer is joined to the perimetrical edge of the array plate and an outermost isolation layer is adapted to be joined to a hull structure of an underwater vehicle. Each isolation layer is made from energy absorbing material and each intermediate layer is made from generally rigid material. The isolation section substantially reduces vehicle self-noise from traveling to the array plate. Interchangeable depth stop members having various geometries are used to adjust the stiffness of the isolation section so as to maximize the isolation characteristics of the isolation section at particular water depths at which the underwater vehicle operates.