A New Low-Cost Acoustic Beamforming Architecture for Real-Time Marine Sensing: Evaluation and Design

Darryl Franck Nsalo Kong,Chuan Tian,Chong Shen,Kun Zhang

doi:10.3390/jmse9080868

Abstract

This paper mainly studies the performance of an acoustic beamforming technique applied to a low-cost hydrophone in a linear array of two to four elements for the detection and localization of underwater acoustic sound waves. It also evaluates the integration of the array in an energy-efficient real-time monitoring system architecture, allowing marine sensing to be conducted without human intervention. Such architecture would consist of vertical linear arrays of two or four RHSA-10 hydrophones models attached to a buoy or a vessel for sound detection; a frequency domain beamformer (FDB) technique implemented in a Xilinx Spartan-7 field programmable gate array (FPGA) for sound source localization; a LoRa wireless sensor network mote to provide convenient access from a base center. The architecture aims to alleviate sea traffic control for countries that lack the financial resources to properly address illegal fishing or piracy issues, mostly committed in small fast motorized boats. In our experiment, the sound waves emitted by a small motorized boat were successfully detected and tracked by three data acquisitions at a 1 km range. It is demonstrated that a system using a small number of hydrophones is capable of producing robust accuracy over a large band frequency in the presence of noise interference.

Highlights

Piracy and illegal fishing are considered the most serious security issues occurring in the high sea
This way, instead of having patrol vessels watching an area, sound waves gathered by a network of buoys are computed by the monitoring system; the resulting data are transmitted through radio frequencies to the base command, and only can the authorities be alerted to apprehend illegal fishing or pirate vessels
Each of the floating buoys is equipped with a global positioning system receiver (GPS), a beamformer fully embedded in a field programmable gate array (FPGA), which processes several operations to detect the signal incoming source, a battery pack, and a wireless sensor mote to relay the input signal location result to a control center and an array of RHSA-10 model hydrophones

Summary

Introduction

Piracy and illegal fishing are considered the most serious security issues occurring in the high sea. Hydrophone array monitoring systems are already used in various applications in the marine sector and, can be a viable alternative for countries that lack the funds to equip themselves with appropriate technology or those facing a too large area to monitor. This way, instead of having patrol vessels watching an area, sound waves gathered by a network of buoys are computed by the monitoring system; the resulting data are transmitted through radio frequencies to the base command, and only can the authorities be alerted to apprehend illegal fishing or pirate vessels

Methods

Results

Conclusion