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.

Abstract: A method and device for improving the restoration of the images obtained from samples taken from acoustic signals received by a lateral aimed sonar provides for the selection of samples from the signals received, the time interval between the samples selected being smaller at the beginning of the echo reception window than at the end thereof so as to improve the power of resolution of the sonar for directions of low obliqueness. The sampling may be carried out at a variable frequency or else at a very high fixed frequency, the selection then being made among all the samples obtained.