Patent ID: 9488745
Filing Date: 2016-11-08
CPC Classification: G01S,G01V

Claim Text:
1. A method comprising: estimating the water speed of a first acoustic node D belonging to a network of acoustic nodes, at least some of said acoustic nodes being arranged along towed acoustic linear antennas, wherein said estimating comprises the following acts performed by a master controller of the network of acoustic nodes or by a navigation system, which is connected to the network of acoustic nodes: a) defining a two-dimensional base, the center of which is said first acoustic node and comprising two non-colinear axes, each said axis being associated with a base vector extending from said first acoustic node to another acoustic node; and b) estimating an amplitude of the water speed, as a function of: wherein act a) comprises defining a two-dimensional base comprising first and second non-colinear axes, the first axis being associated with a first base vector extending from said first acoustic node to a second acoustic node A, the second axis being associated with a second base vector extending from said first acoustic node to a third acoustic node C, the second and third acoustic nodes being arranged along a first acoustic linear antenna, and wherein act b) comprises estimating, in a plan comprising the first, second and third acoustic nodes, an amplitude ∥{right arrow over (WSP)} D ∥ and an orientation angle γ of the first and second base vectors as compared to an axis of said first acoustic linear antenna, of the water speed, by solving the following system of two equations: with tDA being an acoustic propagation duration of an acoustic signal transmitted from the first acoustic node to the second acoustic node; tAD being an acoustic propagation duration of an acoustic signal transmitted from the second acoustic node to the first acoustic node; tDC being an acoustic propagation duration of an acoustic signal transmitted from the first acoustic node to the third acoustic node; tCD being an acoustic propagation duration of an acoustic signal transmitted from the third acoustic nodes to the first acoustic node; c being said value of the underwater acoustic sound velocity; α being the direction of the first axis, as compared to a reference axis; and β being the direction of the second axis, as compared to the reference axis.