Quantifying Self-Noise of the Seaglider AUV Using a Passive Acoustic Monitor

Abstract

Abstract The Seaglider, a type of underwater glider, is a relatively quiet vehicle in comparison with propelled autonomous underwater vehicles, making it a desirable acoustic receiving platform. Vehicle operations, such as pumping/bleeding oil to change buoyancy, shifting/rotating the battery to change pitch/roll, and oceanographic data collection, do, however, produce some self-noise. This system performance study analyzes the prevalence, frequency content, duration, and levels of self-noise associated with vehicle operations using data collected with a passive acoustic monitoring system mounted on the body of a Seaglider vehicle. Guidance and control functions, including pitch, roll, and buoyancy changes, were the major source of platform noise, producing broadband noise ranging from less than a second to over 3 min in duration, with sound pressure levels of 120‐145.5 dB re 1μPa. Frequencies below 10 kHz were the most impacted by self-noise, with a maximum 1/3 octave level of 137.5 dB re 1μPa in the 2.5kHz band caused by the pumping of oil in the variable buoyancy device. Guidance and control changes occurred during 4%‐13% of the dive for dives greater than 500 m. The bulk of these operations, however, were performed near the surface and apogee of the dive and typically affected only about 6% of the dive cycle duration for deep dives.