Prototype development of an underwater sound measurement module using four hydrophones

Recently, Korea Institute of Geoscience and Mineral Resources (KIGAM) is developing an ocean surface/bottom multidisciplinary geophysical observatory that integrates hydroacoustic, seismic, and infrasound technologies. In 2014 Korea Research Institute of Ships and Ocean Engineering (KRISO) developed a prototype of a high-frequency underwater sound measurement module of detecting the hydroacoustic signal in the KIGAM system. The module detects incoming acoustic energy from all horizontal directions using four hydrophones. An array configuration of this module is the star-shaped topology, which is isotropic towards all incoming hydroacoustic signal directions and gives better beam resolution than the circular configuration under non-aliasing spacing condition. It is composed of a real-time signal processing device, a memory, a power controller, an Ethernet hub, a thermometer and a pressure sensor. This paper describes its system configuration and its important features. Also the experiment results of the prototype that was tested and verified in a water tank and at a pier are shown.