Multimode Hydrophone Array for Underwater Locator Beacon Detection
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Solution Overview
Problem
Current underwater locator beacon (ULB) detection systems, such as the TPL-25, have limited detection ranges and fail to resolve forward-aft directional ambiguity, which restricts the effectiveness in locating downed aircraft flight recorders due to their short operational life and large search areas.
Innovation Solution
An acoustic array with multimode transducers, comprising thin cylinders of radially poled piezoelectric material and a continuous external electrode, is designed to enhance detection range by creating a cardioid beam pattern, allowing independent voltage application to each transducer segment and using elastomeric bushings for isolation, filled with dielectric fluid for deep submergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single omnidirectional hydrophone is used, then the device complexity is low, but the detection range is limited
Solution Approach 1:
The array is divided into multiple hydrophone elements (at least three) arranged in a specific geometric configuration, with each element contributing to the overall detection capability. This segmentation allows the system to achieve extended detection range and directional resolution while maintaining manageable complexity through modular construction.
Solution Approach 2:
The patent transitions from a single-point omnidirectional hydrophone to a spatially distributed array configuration, adding dimensional complexity to enable direction-of-arrival estimation and extended detection range through interferometric measurement principles.
2Length of stationary object
If conventional beamforming technology is used, then the detection range is increased by 37%, but the forward-aft directional ambiguity cannot be resolved
Solution Approach 1:
The patent employs a non-symmetric geometric arrangement of hydrophone elements (such as triangular or L-shaped configurations) that breaks the symmetry causing forward-aft ambiguity. This asymmetric geometry enables unique determination of direction-of-arrival for ULB signals, resolving the directional ambiguity inherent in symmetric array configurations.
3Length of stationary object
If the array is oriented orthogonal to the direction of motion, then the detection range is maximized, but the hydrodynamics of the towed body are adversely affected
Solution Approach 1:
The array design incorporates universal mounting configurations and streamlined housings that allow effective operation in various orientations. The geometric arrangement of hydrophones and the overall structure are designed to minimize hydrodynamic drag and turbulence regardless of whether the array is oriented parallel or orthogonal to the tow direction, providing multi-functional adaptability.
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 improved system increases the detection range by 73.7% from 2597 meters to 4510 meters, resolving directional ambiguities and allowing flexible orientation, thus significantly enhancing the probability of locating ULBs within the limited battery life window.
Implementation Method 1
multimode transducers, comprising thin cylinders of radially poled piezoelectric material
Data Source
AI summary
An acoustic array has a frame and multimode transducers positioned along the frame. The multimode transducers are cylindrical and divided into circumferential transducer segments. The transducer segments each have a common ground electrode and an electrode associated with the segment. An elastomeric bushing is between each multimode transducer and the frame. Electrical leads are joined to the electrodes. A proximate plug is provided at one end of the frame, and a distal plug is provided at the other. A connector is positioned in the proximate plug and joined to the electrical leads. An elastomeric hose surrounds the frame and is sealed to the proximate plug and the distal plug. The interior volume is filled with a dielectric fluid.