# The Design and Data Analysis of an Underwater Seismic Wave System

## TL;DR

This paper presents a system for detecting ship seismic waves underwater to improve marine security and monitor illegal activities.

## Contribution

A novel system design and signal analysis framework for high-precision detection of ship seismic waves in marine environments.

## Key findings

- The system successfully measured seismic wave signals in water tank and sea trials.
- The improved ALE-LOFAR and DEMON framework effectively extracted low-frequency signal characteristics of vessels.
- The method supports covert monitoring and early warning for illegal fishing and underwater security.

## Abstract

Ship seismic wave signals represent one of the most critical physical field characteristics of vessels. To achieve the high-precision detection of ship seismic wave field signals in marine environments, an underwater seismic wave signal detection system was designed. The system adopts a three-stage architecture consisting of watertight instrument housing, a communication circuit, and a buoy to realize high-capacity real-time data transmissions. The host computer performs the collaborative optimization of multi-modal hardware architecture and adaptive signal processing algorithms, enabling the detection of ship targets in oceanic environments. Through verification in a water tank and sea trials, the system successfully measured seismic wave signals. An improved ALE-LOFAR (Adaptive Line Enhancer–Low-Frequency Analysis) joint framework, combined with DEMON (Demodulation of Envelope Modulation) demodulation technology, was proposed to conduct the spectral feature analysis of ship seismic wave signals, yielding the low-frequency signal characteristics of vessels. This scheme provides an important method for the covert monitoring of shallow-sea targets, providing early warnings of illegal fishing and ensuring underwater security.