Passive Acoustic Bearing Estimation via 3D Hydrophone Arrays
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Solution Overview
Problem
Traditional methods for tracking sea-going platforms, such as sonar and ultra-short baseline (USBL) positioning, rely on active signals and require knowledge of the signal source, limiting their ability to track unknown or uncooperative platforms.
Innovation Solution
A passive bearing detector system comprising a plurality of hydrophones arranged in a three-dimensional geometry, coupled with a processor that determines the direction of arrival of unknown broadband acoustic signals based on phase differences, allowing for the passive tracking of sea-going platforms without prior knowledge of the signal source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sonar or USBL methods are used for tracking, then location information can be obtained, but the system requires active signals from known locations which can be detected by target platforms and reveals the signal source location
Solution Approach 1:
The patent inverts the traditional active tracking approach by using passive listening. Instead of transmitting signals from a known location and analyzing returns, the system receives unknown broadband acoustic signals from target platforms and determines their direction of arrival. This inversion makes the tracking system invisible to targets while maintaining reliable tracking capability through phase difference analysis of received signals across multiple hydrophones.
Solution Approach 2:
The target platform's own acoustic emissions serve the tracking function. The system utilizes the broadband acoustic signals naturally generated or emitted by the target platform itself, eliminating the need for separate active signaling. The target's self-generated acoustic signature becomes the tracking signal, providing reliable tracking without requiring cooperation from the target or revealing the observer's location.
2Measurement precision
If traditional USBL positioning is used, then position can be determined for known signals, but the system cannot track unknown signals or uncooperative platforms
Solution Approach 1:
The patent creates a universal tracking system that handles both known and unknown signals through the same passive reception and phase difference analysis process. The system uses broadband frequency analysis and phase comparison across multiple hydrophones that works regardless of whether the signal source is known or unknown, cooperative or uncooperative. This multi-functional approach maintains precise position determination while significantly expanding adaptability to various target types and signaling conditions.
Solution Approach 2:
The system changes from requiring specific known signal parameters to analyzing unknown broadband acoustic signals across multiple frequencies. By using phase difference measurements at broadband frequencies rather than relying on predetermined signal characteristics, the system maintains measurement precision while becoming adaptable to any acoustic source emitting broadband signals, including uncooperative platforms.
3Object-generated harmful factors
If passive listening is used to avoid detection, then the system remains undetected, but determining direction of arrival of unknown broadband signals becomes more difficult
Solution Approach 1:
The patent transitions from two-dimensional planar hydrophone arrays to three-dimensional geometric configurations of hydrophones. This spatial dimensionality change enables accurate direction of arrival estimation for unknown broadband signals by providing phase difference measurements from multiple spatial perspectives. The 3D geometry resolves the increased measurement difficulty while maintaining the passive, undetected operation of the system.
Solution Approach 2:
The system replaces complex active signal transmission and processing mechanics with acoustic phase difference analysis. By substituting the mechanical active sonar approach with passive acoustic reception and phase comparison across broadband frequencies, the system reduces the difficulty of direction finding while maintaining stealth. The phase-based method naturally handles unknown signals without requiring active probing or complex signal generation.
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
Enables the accurate determination of the direction of arrival of unknown broadband acoustic signals, facilitating the passive tracking of sea-going platforms, including those that do not actively transmit signals, thereby overcoming the limitations of traditional tracking methods.
Implementation Method 1
The processor is configured to determine at least one direction of arrival of an unknown broadband acoustic signal received by the plurality of hydrophones based on the phase difference of the unknown broadband acoustic signal at each of the plurality of hydrophones
Data Source
AI summary
In various embodiments, a passive bearing detector is disclosed. The passive bearing detector comprises a plurality of hydrophones. The plurality of hydrophones is arranged in a three-dimensional geometry. The three-dimensional geometry exposes each of the plurality of hydrophones to an ambient aquatic acoustic environment. The passive bearing detector further comprises a processor electrically coupled to the plurality of hydrophones. The processor is configured to determine a direction of arrival of an unknown broadband acoustic signal received by the plurality of hydrophones based on the phase difference of the unknown broadband acoustic signal at each of the plurality of hydrophones.