Low-cost underwater acoustic array testbed

Sensor arrays are important signal processing tools for improving Signal-to-Noise Ratio (SNR) and enabling direction finding. Underwater arrays are used in a variety of applications, such as communications, environmental monitoring, and SONAR. Unfortunately, student access to underwater arrays is often limited by the need for expensive specialized hardware. This talk presents a flexible, low-cost underwater acoustic array testbed built with consumer off the shelf components. The system costs approximately $2200. The transmitter consists of an amplifier driven by a standard laptop audio output and a Lubell Labs UW30 transducer. The receiver consists of an array of four Aquarian Audio A5 hydrophones connected to a USB audio interface for data acquisition by a second laptop. The talk describes the system design and characterizes the transmitter and receiver frequency responses. An experiment illustrates how the testbed can facilitate the study of arrays in underwater communications. The transducer and array are deployed in shallow water environments, i.e., a competition pool and a lake. The experiment measures output SNR and bit error rate using several communication protocols, including on-off keying and frequency-shift keying.