Inflatable Bladder for Shallow-Water Acoustic Shadow Penetration

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Solution Overview

Problem

Robust and reliable horizontal long-range acoustic communications in shallow-water environments are challenging due to disturbances caused by fluctuations in water layers, leading to acoustic shadows and severe multi-path effects, which current modulation schemes like OFDM and DSSS struggle to overcome.

Innovation Solution

A shallow-water acoustic communication system that generates internal wave fluctuations to change the sound speed profile by using a fluid pressure source and an elongated flexible bladder to drive a pumping current, disrupting acoustic communication shadows and improving signal penetration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional modulation schemes (OFDM, DSSS) are used, then communication robustness against multi-path effects is improved, but communication reliability in shallow-water shadows deteriorates

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidacoustic shadow blocking

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the physical parameters of the water column by generating internal waves that modify the sound speed profile. This dynamic parameter change alters the acoustic propagation conditions, enabling signals to penetrate shadow regions by changing the refraction characteristics of sound waves in the water column.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system uses mechanically generated internal waves (vibrations in the water column) to create fluctuations in the sound speed profile. These vibrations are produced by devices that generate internal waves at specific frequencies, causing the water layers to oscillate and thereby modify acoustic propagation paths through the shadow regions.

Inventive Principle:

Principle #18Mechanical vibration

2Reliability

If internal wave fluctuations are generated to change sound speed profile, then penetration through acoustic shadows is improved, but device complexity increases

Engineering Contradiction:

Improvesignal penetration capabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention uses pneumatic and hydraulic mechanisms to generate internal waves. Air or water pressure is applied to flexible bladders or tubes, creating pressure-driven oscillations in the water column. This approach uses readily available pneumatic/hydraulic technology to produce the required mechanical vibrations, avoiding more complex electromagnetic or chemical methods.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The system employs flexible bladders or thin-walled tubes as the active element for generating internal waves. These flexible structures can be inflated or pressurized to create oscillations, and they naturally couple with the surrounding water to generate internal wave fluctuations. The flexibility allows efficient energy transfer from the pressure source to the water column with simple construction.

Inventive Principle:

Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively penetrates shallow-water shadows by altering the sound speed profile, enhancing communication reliability and range through the use of a flexible bladder and acoustic modem, allowing for improved signal propagation in unstable littoral environments.

Implementation Method 1

A fluid flow from the output of the source is directed through the bladder to create a pumping current, which drives an up and down vertical action of a sound speed profile adjacent to and beyond the bladder

Methodology Applied

Scientific EffectFluid flow through flexible bladder creating pumping current:

Implementation Method 2

This action disrupts shallow-water acoustic communication shadows in the path of the communication signal, allowing for improved penetration through the shadows

Methodology Applied

Scientific EffectSound speed profile change disrupting acoustic shadows: Refraction

Data Source

PatentUS11431421B1Caustic expander and local waveguide to improve acoustic communications

Publication Date: 2022.08.30 USA AS REPRESENTED BY THE SECRETARY OF THE NAVY

AI summary

A system for improving acoustic communications in a shallow-water environment is provided. The system includes a pump, an elongated inflatable bladder and an acoustic communication modem and transducer. The pump forces water through the bladder, which creates a pumping current. This pumping current drives the sound speed profile up and down vertically, resulting in changes to shallow-water acoustic communication shadows and resultant improved acoustic communication. The bladder may be biased to return to a coiled shape after operation of the pump. The system may be mounted on a turntable to be able to direct the bladder in a preferred direction. Equipment can be attached to the end of the bladder and be transported with the uncoiling and recoiling of the bladder.