US 12,332,348 B2
Depointable parametric echosounder, and method for characterizing a portion of the sub-bottom of a subaquatic environment
Frédéric Mosca, Saint-Germain-en-Laye (FR); and Guillaume Matte, Saint-Germain-en-Laye (FR)
Assigned to EXAIL, Saint-Germain-en-Laye (FR)
Appl. No. 17/793,352
Filed by IXBLUE, Saint-Germain-en-Laye (FR)
PCT Filed Jan. 15, 2021, PCT No. PCT/EP2021/050850
§ 371(c)(1), (2) Date Jul. 15, 2022,
PCT Pub. No. WO2021/144444, PCT Pub. Date Jul. 22, 2021.
Claims priority of application No. 2000464 (FR), filed on Jan. 17, 2020.
Prior Publication US 2023/0036543 A1, Feb. 2, 2023
Int. Cl. G01S 15/89 (2006.01); G01S 15/10 (2006.01)
CPC G01S 15/104 (2013.01) [G01S 15/89 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A parametric echosounder comprising:
a transmitting antenna comprising a plurality of transducers;
at least one receiver; and
a driving and acquisition system configured to execute the following steps:
a) driving said transducers so that the transducers transmit, in an underwater environment, a first acoustic wave having a first frequency and a second acoustic wave having a second frequency, the first wave and the second wave superposing each other along a superposition axis directed towards a point of a bottom of the underwater environment, each of the transducers being driven by a transmit signal, transmit signals of the transducers having predetermined delays with respect to each other, and
b) acquiring at least one echo signal, of frequency equal to a difference between said first frequency and said second frequency, picked up by said at least one receiver in response to the transmission made at step a),
the driving and acquisition system being configured to execute all of steps a) and b) several times, by varying a part at least of said predetermined delays from one execution of the step a) to a next execution of step a), to modify an orientation of said superposition axis from one execution of step a) to the next execution of the step a), and
c) determining, based on the at least one echo signal acquired during different executions of step b), a two-dimensional or three-dimensional image representative of a content of a sub-bottom of the underwater environment below each of said points of the bottom,
the driving and acquisition system being further configured to, at step a):
drive each of the transducers of a first group of said transducers by a first transmit signal varying over time at said first frequency, the transducers of the first group transmitting said first acoustic wave, the different first transmit signals having first delays, predetermined with respect to each other,
drive each of the transducers of a second group of said transducers by a second transmit signal varying over time at said second frequency, the transducers of the second group transmitting said second acoustic wave, the different second transmit t signals having second delays, predetermined with respect to each other, and
vary one or more of said first delays and said second delays from one execution of step a) to the next execution of step a), to modify the orientation of said superposition axis from one execution of step a) to the next execution of step a),
said transducers being arranged to form a matrix of several lines and several columns, the transducers being respectively located at intersections between lines and columns of the matrix,
the first and second delays being such that the first and second acoustic waves are transmitted as a first collimated beam and a second collimated beam, respectively, each centered to said superposition axis,
the transducers of the first group occupying several distinct areas of said matrix, one or several of the transducers of the second group being interposed between any two of said distinct areas,
each transducer of the first group having transducers of the second group as nearest neighbors.