Active Sonar Target Range Error Estimation via Multipath Eigenrays
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Solution Overview
Problem
Conventional active sonar systems face inaccuracies in target range detection due to linear path assumptions, leading to errors in underwater environments with varying sound velocities and multipath propagation, which can result in poor accuracy and failure in rapid anti-submarine warfare operations.
Innovation Solution
A method that predicts the path of sound pulses in active sonar systems by considering multipath eigenrays and environmental data, filtering dominant paths, and calculating target range errors within a search range boundary, allowing for precise detection of target ranges by matching arrival times and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If linear path assumption is used for target range calculation, then calculation speed is improved and operation is simplified, but target range accuracy deteriorates due to multipath propagation and sound velocity variations
Solution Approach 1:
The patent segments the sound propagation path into multiple discrete paths (direct path, surface-reflected path, bottom-reflected path, etc.) and calculates the arrival time for each segment separately. By dividing the complex multipath propagation into manageable path segments, the system can accurately track each path's contribution while maintaining computational efficiency through structured processing of segmented path data.
Solution Approach 2:
The patent transitions from 2D horizontal range calculation to 3D spatial analysis by incorporating depth information and vertical sound velocity profiles. The ray tracing algorithm operates in three-dimensional space, considering depth-dependent sound velocity variations and multiple reflection surfaces (surface and bottom), thereby resolving the accuracy issue caused by linear 2D assumptions while maintaining computational feasibility through dimensionally-enriched modeling.
2Ease of operation
If reference sound velocity value is used for target range detection, then detection process is simplified and speed is improved, but detection accuracy deteriorates in environments with varying sound velocities
Solution Approach 1:
The patent replaces static reference sound velocity values with dynamic, depth-dependent sound velocity profiles that adapt to environmental conditions. The system uses vertically-varying sound velocity data and updates the propagation model accordingly, allowing the detection process to automatically adjust to changing environmental conditions while maintaining operational simplicity through automated profile-based calculations.
Solution Approach 2:
The patent changes the sound velocity parameter from a single reference value to a depth-dependent function. By incorporating sound velocity profiles that vary with depth and environmental parameters (temperature, salinity, pressure), the system achieves accurate target range detection in varying environments while maintaining computational efficiency through parameterized modeling approaches.
3Measurement precision
If multipath eigenray prediction is performed to improve target range accuracy, then measurement precision is improved, but device complexity and calculation load increase
Solution Approach 1:
The patent performs preliminary ray tracing calculations to predict all possible propagation paths (direct, surface-reflected, bottom-reflected, etc.) before target detection. By pre-calculating the eigenrays and their arrival times based on environmental profiles, the system prepares the propagation model in advance, reducing real-time computational complexity while maintaining high accuracy in target range measurement.
Solution Approach 2:
The patent creates a virtual copy of the underwater acoustic environment including sound velocity profiles, reflection surfaces, and propagation paths. This virtual model allows the system to simulate and predict multipath eigenrays without requiring complex physical measurements during detection, thereby reducing device complexity while maintaining measurement precision through accurate environmental modeling.
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
This approach enables precise and accurate target range estimation by accounting for multipath effects and sound velocity variations, reducing errors and enhancing the reliability of active sonar systems in complex underwater environments.
Implementation Method 1
an acoustic pulse transceiver 2 transmits a sound pulse through an acoustic sensor 1, and receives a signal reflected from a target
Implementation Method 2
the active sonar system serves to detect an echo reflected from a target by emitting a sound pulse
Implementation Method 3
A signal processor 3 performs a signal process such as beam-forming with respect to the received signal
Data Source
AI summary
Disclosed is an active sonar system capable of estimating a direction and a range of a target by using a sound pulse. A target range error can be estimated by the active sonar system, by applying a principle that a sound pulse used to detect an underwater target with consideration of a vertical structure of a sound velocity in water is reflected and refracted through a multipath not a linear path.