Abstract: Disclosed is a bathymetric system including a multi-beam emitting and receiving device attached to a carrier vehicle, configured, in a first recurrence, to measure the amplitude of a first plurality of beams reflected off the seabed, and a computer to determine three-dimensional spatial coordinates of a first scan swath. In a second recurrence, the device emits a second incident beam and measures the amplitude of a second plurality of beams reflected off the seabed, the computer determines the three-dimensional spatial coordinates of a second scan swath, so that at least one probe point of the first scan swath is redundant with a probe point of the second scan swath, and the computer calculates an altitude variation of the carrier vehicle using altitude variations of the at least one redundant probe point between the first recurrence and the second recurrence.

Abstract: Disclosed is a method for determining a difference in depth or a lateral distance in relation to the vertical between two points of an underwater environment, in particular by measuring a propagation time of a sound wave. The determination is based on a single-layer model of the environment in which the wave is supposed to propagate in a straight line along an effective propagation direction, at a mean velocity that is independent of the propagation direction. Also disclosed is a method for determining the profile of the mean velocity based on the measurements of differences in depths per se, a determination of the local velocity profile over the variation interval of the sounded depths, and a related sonar system.

Abstract: Disclosed is a bathymetric system including a multi-beam emitting and receiving device attached to a carrier vehicle, configured, in a first recurrence, to measure the amplitude of a first plurality of beams reflected off the seabed, and a computer to determine three-dimensional spatial coordinates of a first scan swath. In a second recurrence, the device emits a second incident beam and measures the amplitude of a second plurality of beams reflected off the seabed, the computer determines the three-dimensional spatial coordinates of a second scan swath, so that at least one probe point of the first scan swath is redundant with a probe point of the second scan swath, and the computer calculates an altitude variation of the carrier vehicle using altitude variations of the at least one redundant probe point between the first recurrence and the second recurrence.

Abstract: A metrology method and device for calibrating the geometry of a network of Nb stationary underwater acoustic beacons (11, 12, 13, 14) defining a field of beacons, implementing a moving body (20) including elements for receiving acoustic signals from each of the beacons of the network, respectively. The metrology method includes the following steps: acquiring Nm series of Nb acoustic measurements of the relative distance between the moving body and each beacon of the network, respectively, during a movement of the moving body; calculating a numeric function C from the series of acoustic measurements of the relative distances and parameters representing relative positions of the beacons; executing an algorithm for minimising the numeric function C in order to deduce therefrom an estimation of the values of the relative position parameters of each of the beacons of the network.

Abstract: An acoustic positioning device includes an acoustic emitter and receiver. The device emits a sequence of at least one first acoustic signal (S1) and one second acoustic signal (S2), separated by a time interval T, and to receive and measure the arrival phase ?1 of S1 and the arrival phase ?2 of S2. The device measures a relative displacement between the acoustic emitter and the acoustic receiver and determines the approximate difference (R2?R1)AUX between the distance R1 traveled by S1 between the acoustic emitter and receiver, and the distance R2 traveled by S2 between the acoustic emitter and the acoustic receiver, and calculates the relative displacement (R2?R1) between the acoustic emitter and the acoustic receiver as a function of the approximate difference (R2?R1)AUX, of the time interval T and of the arrival phases ?1, ?2 respectively of S1 and of S2.

Abstract: An acoustic positioning device includes an acoustic emitter and receiver. The device emits a sequence of at least one first acoustic signal (S1) and one second acoustic signal (S2), separated by a time interval T, and to receive and measure the arrival phase ?1 of S1 and the arrival phase ?2 of S2. The device measures a relative displacement between the acoustic emitter and the acoustic receiver and determines the approximate difference (R2?R1)AUX between the distance R1 travelled by S1 between the acoustic emitter and receiver, and the distance R2 travelled by S2 between the acoustic emitter and the acoustic receiver, and calculates the relative displacement (R2?R1) between the acoustic emitter and the acoustic receiver as a function of the approximate difference (R2?R1)AUX, of the time interval T and of the arrival phases ?1, ?2 respectively of S1 and of S2.

Abstract: A synthetic antenna sonar system, includes: a sonar provided with emission elements and reception elements, the reception elements including a composite physical antenna having N transducers, the sonar being located on a mobile carrier; an inertial unit arranged on the carrier and suitable for measuring instantaneous position and orientation informations of the carrier; a common clock supplying a temporal signal enabling the synchronization of both the inertial unit and the sonar; elements for determining the instantaneous speed of the carrier, the determined speed feeding the inertial unit to correct the drift thereof; and micronavigation elements enabling an image of the seafloor to be obtained through formation of the synthetic antenna channels from K sonar operation recurrences, considering that the physical antenna movement during the carrier displacement is fully known from the informations measured by the inertial unit.

Abstract: The invention concerns a method for acquiring and processing magnetometric data for representing on an at least two-dimensional map magnetometric characteristics of a geographical zone including a step of measuring the intensity of a magnetic field (1) on a geographical zone producing a set of magnetometric data of intensity B(s), a step of computing 2D interpolation (3), a step of computing reduction at the poles (5) and a step of computing an analytical signal (7). The invention is characterized in that it includes sectioning the map of magnetic disturbances into a matrix of pixels, a step of locally updating in real time the map of magnetic anomalies, a step of locally updating in real time the map of 2D interpolation by applying the 2D interpolation calculation in the neighborhood of the updated pixel, a step of locally updating in real time the 2D map of reduction at the poles and a step of locally updating in real time the 2D map of the analytical signal.

Abstract: The invention concerns a method for acquiring and processing magnetometric data for representing on an at least two-dimensional map magnetometric characteristics of a geographical zone including a step of measuring the intensity of a magnetic field (1) on a geographical zone producing a set of magnetometric data of intensity B(s), a step of computing 2D interpolation (3), a step of computing reduction at the poles (5) and a step of computing an analytical signal (7). The invention is characterized in that it includes sectioning the map of magnetic disturbances into a matrix of pixels, a step of locally updating in real time the map of magnetic anomalies, a step of locally updating in real time the map of 2D interpolation by applying the 2D interpolation calculation in the neighbourhood of the updated pixel, a step of locally updating in real time the 2D map of reduction at the poles and a step of locally updating in real time the 2D map of the analytical signal.

Abstract: A synthetic antenna sonar system, includes: a sonar provided with emission elements and reception elements, the reception elements including a composite physical antenna having N transducers, the sonar being located on a mobile carrier; an inertial unit arranged on the carrier and suitable for measuring instantaneous position and orientation informations of the carrier; a common clock supplying a temporal signal enabling the synchronization of both the inertial unit and the sonar; elements for determining the instantaneous speed of the carrier, the determined speed feeding the inertial unit to correct the draft thereof; and micronavigation elements enabling an image of the seafloor to be obtained through formation of the synthetic antenna channels from K sonar operation recurrences, considering that the physical antenna movement during the carrier displacement is fully known from the informations measured by the inertial unit.

Abstract: An optical device for generating a signal based on a distance of an object from the optical device. The optical device includes a first polarizer, a birefringent crystal positioned optically downstream from the first polarizer, and a second polarizer arranged optically downstream from the birefringent crystal. The second polarizer creates a pair of interferograms by adjusting a phase of the light. Two outputs are generated by separately integrating an amount of light of at least a part of each of the pair of interferograms. Finally, the two outputs are combined such that the signal, depending only on the distance between the object and the optical system, is obtained.

Abstract: The present invention concerns a holographic process including a stage consisting in producing the hologram of a point P thank to an optical device including a crystal (131) and two polarizers (132,135) placed respectively before and after the crystal (131), characterized by the fact that it includes in addition the stages consisting in: 1) separating the answers of the optical system corresponding to two different polarizations and 2) combining both these answers in order to obtain a signal which depends only on the distance between the point P ant the optical device. The invention concerns also a device which allows the implementation or this process.

Abstract: The memory (DAT) with blocks (BL) organized in N columns of n levels is managed by a method consisting of prohibiting access to blocks that are unusable because of operating defects, by associating the unusable blocks with a flag (F) advantageously incorporated into the addresses of the blocks. When these addresses incorporate at least two bits combined to indicate the states of the block at that address, the flag (F) may be a free combination of these two bits.

Abstract: A first input-first output type circuit manages m n-bit words using m stages connected in series with first and second non-overlapping clock signals controlling even-numbered and odd numbered ones of the m stages, respectively. A process for controlling the circuit involves a first write step during which each word in a first half of the m words is written into both an odd-numbered stage and a successive even numbered stage so that m/2 of the m words occupy all m of the stages. After the first write step is completed, a second write step begins during which the m/2 words written during the first write step are shifted and stored in the ((m/2)+1)-th through m-th stages. Writing is disabled in each of the m stages beginning with the m-th stage and proceeding successively to the first stage. The m/2 words not written during the first write step are written into those stages not yet disabled in the same manner as in the first write step.

Abstract: A method of generating a quasi-complex hologram using incoherent light and a conoscope system comprising a birefringent crystal (30) inserted between two circular polarizers (10, 20), the method comprising the following steps: (i) recording a plurality of different conoscopic holograms of the same object without relative displacement thereof and with respective different polarization configurations; and (ii) combining the various conoscopic holograms obtained in this way in order to remove the bias and the conjugate image. The invention also relates to a device for implementing the method.