Experimental Demonstration of a Single Acoustic Vector Sensor for JANUS Performance Enhancement

This study shows the underwater communication performance using an acoustic pressure-gradient vector sensor. Combining the estimated particle velocity channels with the acoustic pressure results in a cardioid-like beam steered output, which is used to improve the signal-to-noise ratio. A shallow-water field experiment was carried out using a single vector sensor as a receiver and a ship-suspended sound source, transmitting the frequency-hopped JANUS modulated signal at several ranges and directions. Bit error rate analysis demonstrates how performance can be enhanced through vector sensor channel combining. Firstly, by relating the error with beam pattern varying the azimuth steering angle. Second, by relating the error with transmitting stations, where individual channels of the vector sensor can be compared. Besides such findings, this study also presents tools for better understanding the directional characteristic, such as the design factor to combine the particle velocity to the pressure sensor and azigrams. Finally, results show that the JANUS bit error rate can be reduced up to five percent by combining the vector sensor components compared to the pressure sensor.