Abstract: Acoustic distance measuring apparatus for measuring the distance of a vessel (N) from a vertical line through a fixed point (P) on the bottom of a body of water, the apparatus comprising: an acoustic emitter unit (I) and at least three acoustic receiver units (H1, H2, H3) disposed on the bottom of the vessel, said receiver units being disposed at the vertices of a plane polygon; at least three acoustic emitter/receiver units (A, B, C) placed on the water bottom in the vicinity of said fixed point (P), said emitter/receiver units being disposed at the vertices of a polygon; and the improvement wherein the measuring apparatus further includes a relay acoustic emitter/receiver (R) submerged close to the vessel at a depth where vessel noise is highly attenuated, said relay receiing acoustic waves (a) from the vessel's emitter and responding by emitting acoustic wave (1, 2, 3) to the vessel's receiver units thereby enabling the distances between the relay and each of the vessel's receiver units to be calculated, s

Abstract: A sonar system comprises a vehicle (1) capable of moving over the bottom of an extent of water, with an emitter of acoustic pulses and a receiver of acoustic energy mounted on said vehicle. Signal processing and display circuitry (e.g. on board a surface vessel 2) are connected to receive signals representative of the acoustic waves emitted by the emitter, of the acoustic waves received by the receiver, and of parameters describing the motion of the vehicle. The signal processing and display circuitry generates an image of objects hidden in the water bottom on the basis of the signals. The emitter of acoustic pulses is provided with at least one parametric transducer having a spot radiation pattern capable of forming a plurality of channels that bathe spots of the water bottom in sound waves, and an electronic pointing system for scanning the channels.

Abstract: Device for forming channels using detectors spaced out on a circular base, comprising detectors evenly spaced out and followed by coders, means for distributing the data supplied by those coders, a chain constituted by an alternate sequence of delay devices and adders; the distributing means are simplified and comprise an input shift register associated with buffer memories. Application to the determining of the propagation of a plane wave in sonars.

Abstract: Device for forming channels using detectors regularly spaced out on a cirar base comprising a chain constituted by an alternate sequence of identical adders and identical delay devices. The outputs of the detectors are sampled and applied through shift registers enabling them to be delayed more or less on the lateral inputs of the adders. The device comprises less elements than known channel forming devices. Application to sonars.

Abstract: The invention concerns a position measuring device used for measuring the position of a vessel equipped with three hydrophones arranged at the apexes of a triangle in relation to a transmitting beacon on the sea bed. Measuring of the differences in the travel time between the beacon and the various hydrophones as well as of the depth of the water and analogic calculating of the position of the vessel in a simple way and without approximation. Application to offshore drilling vessels.

Abstract: Device for forming channels using detectors spaced out on a circular base, comprising detectors evenly spaced out and followed by coders, means for distributing the data supplied by those coders, a chain constituted by an alternate sequence of delay devices and adders; the distributing means being simplified and comprising an input shift register associated with buffer memories. Application to the determining of the propagation of a plane wave in sonars.

Abstract: The invention concerns a position measuring device used for measuring the sition of a vessel equipped with three hydrophones arranged at the apexes of a right-angled triangle in relation to a transmitting beacon on the sea bed. Measuring of the differences in the travel time between the beacon and the various hydrophones as well as of the depth of the water and analogic calculating of the position of the vessel in a simple way and without approximation.