Abstract: A parallel memory configured to enable access to a table with aligned and equidistant components constituting a vector of N components. The memory (1) is organized as M memory banks (8). Each memory bank (8) includes an address calculator. The memory (1) also includes a unidirectional network (6) configured to carry out a permutation of the N components of the vector being accessed and to carry out a translation by a specified value t of the components of the vector.

Abstract: A system for underwater seismic prospecting or exploration on seafloors, especially deep seafloors, including streamers designed to contain the measurement devices and to lie on the seafloor, in the form of an inner tube that is non-stretching and non-compressible and an outer tube that is extensible to a certain extent. Through the injection of liquid between these two tubes, the buoyancy of each streamers is made positive. This enables it to be detached from the seafloor and towed to the next measuring position.

Abstract: Acoustic transmitting antennas in the form of circular rings. Several circular rings which can be dismantled of a known type are superimposed in a stack. The stack is terminated at each end by two profiled annuli. The threaded tie-rods traverse the stacks of the pre-stressing keys of the rings by the intermediary of holes drilled in these keys. The threaded tie-rods make it possible to ensure the holding of the assembly. Two jackets, inside and outside, made of rubber, cover the inside and outside faces of the stack and are anchored in grooves formed in the profiled annuli. Thereby, annular transmitting antennas can be provided which can be dismantled entirely and whose active mass to inactive mass ratio is particularly large.

Abstract: The invention relates to synthetic antenna sonars. It consists, in order to correct the effects of the spurious motions of the physical antenna (202) of this sonar, in simultaneously using an autofocussing by crosscorrelation of the recurrences, a measurement of the rotation of the physical antenna with a rate gyro, and a correction of this measurement of rotation on the basis of the measurement of the angle of elevation of the reception signal as obtained with the aid of an auxiliary antenna (203) perpendicular to the physical antenna. It makes it possible to obtain synthetic antenna sonars having excellent spatial resolution.

Abstract: A method of readjusting sonar images using sub-antennae. For each point of the bottom, a sub-antenna is constructed of a given size at one end of the physical antenna. A first channel is constructed over a short time slice centered on the point. A sub-antenna is also constructed upon recurrence No. 2 of the same size as the first one, but at the opposite end of the physical antenna. With the second sub-antenna, a plurality of second channels is formed over a sector which is sufficiently wide to contain the point. These second channels are intercorrelated with the first channel so as to adopt the one which maximizes the intercorrelation peak. This procedure is repeated for different sub-antenna sizes and one is adopted which produces the maximum of the preceding intercorrelations.

Abstract: A synthetic-antenna side sonar device. Two transmission transducers which operate in interferrometric mode are fixed to the two ends of a physical antenna of a sonar. The forward speed of the sonar is chosen so that the zeros of the physical reception antenna coincide with one out of two of the side lobes of the radiation diagram of the synthetic antenna. Also the speed is chosen so that the zeros of the physical diagram of the interferrometric transmission antenna coincide with the other side lobes. This arrangement increases the range and thus the hourly coverage of a sonar for a given speed.

Abstract: The invention relates to methods which make it possible to measure the Doppler shift of the echoes of a detection system. That is, the present invention modulates the frequency of the pulses of the transmissions of this system by a pseudohyperbolic function such that a restricted number of copies of the transmission signal can be used to perform the correlation operations on reception and to have them followed by an interpolation operation.

Abstract: The invention relates to underwater mines countermeasures methods and devices that can be employed from a helicopter.It consists in using the body (101) of a known passive heli-winched sonar, fitting to it emitting antennas (105, 106) arranged in this body parallel to its axis and a receiving antenna perpendicular to this axis and formed of two articulated arms (107, 108) that can be retracted inside the body. Two other arms (114, 113) that can be retracted into the body have propulsion means (111, 112) at their free ends, to allow the body to be stabilized about its axis.The invention makes it possible to employ lightweight helicopters for underwater mines countermeasures, allowing the mines to be relocated and, if appropriate, destroyed without having to backtrack.