Sintra-alcatel

Claude Leroy

Guy Parent

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, said bottom emitter/receiver units also receiving acoustic waves (a) from the vessel's emitter and being arranged to respond in succession, i.e. after respective predetermined time delays, by emitting acoustic signals (f2) which are received by the relay and which are re-emitted (4) therefrom after amplification to be received by one of the vessel's receiver units (H1), thereby enabling the distances between the relay and each of the bottom emitter/receivers (RA, RB, RC) to be calculated on the basis of the different transit times for the signals from each bottom emitter/receiver, and further enabling the distance of the vessel from a vertical line through said fixed point to be calculated.

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Bandol, France

Claude Leroy