Sonar system with curved antenna or antenna configured to transmit the same transmission pattern as the curved antenna

Patent metadata

Field	Value
Publication number	US-10061022-B2
Application number	US-201414908477-A
Country	US
Kind code	B2
Filing date	Jul 24, 2014
Priority date	Aug 2, 2013
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

A sonar system to image the seabed, comprises at least one emission antenna to emit an acoustic beam covering a useful angular sector delimited by a first direction and a second direction, the distance between the antenna and the seabed being more significant in the first direction than in the second direction. The emission device is configured to form an emission pattern whose maximum is situated substantially in the first direction and which decreases from the first direction to the second direction and from the first direction in the sense opposite to the second direction, the energy attenuation being faster in the sense opposite to the second direction than toward the second direction.

First claim

The invention claimed is:

1. A sonar system to image the seabed, the sonar system comprising:
at least one emission antenna to emit an acoustic beam directed toward the seabed covering a useful angular sector starting from the antenna and delimited by a first direction and a second direction inclined with respect to the horizontal and the vertical, the first direction forming a first angle with the horizontal smaller than a second angle formed between the second direction and the horizontal,
wherein the emission antenna is configured to form an emission pattern with energy emitted by the emission antenna in each direction of the useful ideal sector, and the emitted energy decreases from the first direction to the second direction,
wherein a portion of the useful angular sector is delimited by the second direction and a third direction lying between the first direction and the second direction, an ideal emission pattern comprising, in each direction of the portion of the useful angular sector, an ideal attenuation DE of

DE
⁡

(
θ
)

=

40
⁢

⁢

log
⁡

(

sin
⁢

⁢

θ
1

sin
⁢

⁢
θ

)

where θ is an angle formed between the direction and the horizontal and θ 1 is the first angle,
wherein the emission antenna comprises an emitting surface exhibiting a profile in a plane perpendicular to a reference plane formed by the first direction and the second direction, the profile having a curve with a radius of curvature that varies along a curvilinear abscissa, such that the emission pattern of the emission antenna in each direction θ of the useful angular sector exhibits an energy attenuation with respect to energy emitted along the first direction which is equal or superior to the ideal attenuation, the ideal attenuation being at least 3 dB and at most 15 dB.

2. The sonar system of claim 1 , wherein the third direction is a direction for which the attenuation is substantially equal to 3 dB, the angle formed between the third direction and the first direction being less than 3 degrees.

3. The sonar system of claim 1 , wherein the emitting surface is a curved surface.

4. The sonar system of claim 1 , wherein the radius of curvature of the emitting surface increases with the distance separating the point considered of the emitting surface from an ideal seabed along a direction perpendicular to the ideal seabed.

5. The sonar system of claim 1 , wherein the curve formed by the emitting surface in a sectional plane of the antenna perpendicular to the longitudinal axis is formed by a single transducer.

6. The sonar system of claim 1 , wherein the pointing of said emission antenna is offset in terms of a bearing.

7. The sonar system of claim 1 , comprising a carrier, the emission antenna being installed on the carrier.

8. The sonar system of claim 1 , wherein the emission antenna is arranged in such a way that the emitting surface extends longitudinally along an axis parallel to the direction of displacement of the carrier.

9. The sonar system of claim 8 , comprising two emission antennas fixed to port and to starboard of the carrier.

10. The sonar system of claim 1 , wherein the first direction is the direction of maximum range of the sonar system and the second direction is the direction of minimum range of the sonar system.

11. The sonar system of claim 1 , wherein the profile is constant along the whole length of the emitting surface.

12. A sonar system to image the seabed, the sonar system comprising:
at least one emission antenna to emit an acoustic beam directed toward the seabed covering a useful angular sector starting from the antenna and delimited by a first direction and a first direction inclined with respect to the horizontal and the vertical, the first direction forming a smaller angle with the horizontal than an angle formed between the second direction and the horizontal,
wherein the emission antenna is configured to form an emission pattern with energy emitted by the emission antenna in each direction of the useful ideal sector, and the emitted energy decreases from the first direction to the second direction,
wherein a portion of the useful angular sector is delimited by the second direction and a third direction lying between the first direction and the second direction, an ideal emission pattern comprising, in each direction of the portion of the useful angular sector, an ideal attenuation DE of

DE
⁡

(
θ
)

=

40
⁢

⁢

log
⁡

(

sin
⁢

⁢

θ
1

sin
⁢

⁢
θ

)

where θ is an angle formed between the direction and the horizontal and θ 1 is the first angle,
wherein the emission antenna comprises an emitting surface forming a curve in a sectional plane of the antenna perpendicular to the longitudinal axis, said curve being formed by a plurality of transducers, said emission antenna further comprises a power feed device feeding the respective transducers with one and the same signal imbued with respective phase shifts and/or amplitude modulation such that the emission pattern of the antenna in each direction θ of the portion of the useful angular sector exhibits an energy attenuation with respect to energy emitted along the first direction which is equal or superior to the ideal attenuation, the ideal attenuation being at least 3 dB and at most 15 dB.

13. The sonar system of claim 12 , wherein the third direction is a direction for which the attenuation is substantially equal to 3 dB, the angl

Assignees

• Thales Sa

Inventors

• Guthmann Pierre
• Mandelert Nicolas
• Ferrara Patrick

Classifications

• G10K11/348

  using amplitude variation · CPC title

• G10K11/346

  using phase variation · CPC title

• G01S15/8902

  Side-looking sonar · CPC title

• G01S7/524 Primary

  Transmitters · CPC title