Abstract: Sonar intended to be carried by a naval vehicle including at least one element for transmitting an acoustic signal, at least one element for receiving the acoustic signal transmitted and reflected on the sea bed and at least two phase centers (PC1, PC2) that are disposed along a first and a second axis (v1, v2), respectively, forming an interferometric antenna. The sonar includes elements for determining the speed of movement of the vehicle as a function of the computed value of the relative trim angle (?) formed between a straight line (d1) that is perpendicular to the axes (v1, v2) of the phase centers and a straight line (d2) that is perpendicular to the sea bed (F) and of the value determined for the angle of sight.

Abstract: Sonar intended to be carried by a naval vehicle including at least one element for transmitting an acoustic signal, at least one element for receiving the acoustic signal transmitted and reflected on the sea bed and at least two phase centres (PC1, PC2) that are disposed along a first and a second axis (v1, v2), respectively, forming an interferometric antenna. The sonar includes elements for determining the speed of movement of the vehicle as a function of the computed value of the relative trim angle (?) formed between a straight line (d1) that is perpendicular to the axes (v1, v2) of the phase centres and a straight line (d2) that is perpendicular to the sea bed (F) and of the value determined for the angle of sight.

Abstract: A system and method for detecting and measuring phenomena relating to altimetric variations in the seafloor. The system including an autonomous submarine vehicle equipped with at least one interferometric sonar sensor configured to send an acoustic signal towards the seafloor and acquire the image of the seafloor generated by the reflection of said acoustic signal sent. The system also including a plurality of elements reflecting sound waves firmly fixed to the seafloor so as to outline a reference path for the passage of the autonomous submarine vehicle.

Abstract: The present invention relates to a system and method for detecting and measuring phenomena relating to altimetric variations in the seafloor. The system (100) according to the present invention comprise an autonomous submarine vehicle (101) equipped with at least one interferometric sonar sensor (102) for sending an acoustic signal towards the seafloor and acquiring the image of the seafloor generated by the reflection of said acoustic signal sent, and is characterized in that it comprises a plurality of elements (103, 103?) reflecting the sound waves firmly fixed to the seafloor so as to outline a reference path for the passage of the autonomous submarine vehicle (101).

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: A method and apparatus for studying the flow of water along a well, on the basis of a general spectrum g(t) of gamma ray detection numbers detected in a detection zone over a given detection duration and as a function of time, said gamma rays resulting from the activation of oxygen atoms in water by neutrons emitted by a source to create an activation reaction O.sup.16 (n,p)N.sup.16.