The Marine Physical Laboratory, Scripps Institution of Oceanography operates several underwater vehicles including an autonomous underwater glider based on a flying wing design and two prop-driven autonomous underwater vehicles (AUV) manufactured by Bluefin Robotics. The objective of this presentation is to describe the acoustic sensor systems on these platforms and provide sample results from the at-sea data. The glider, with a 6.1-m wing span, was developed jointly by the Marine Physical Lab and the Applied Physics Laboratory, University of Washington. It is designed to maximize the horizontal distance traveled between changes in buoyancy (i.e., maximize its "finesse") while quietly listening to sounds in the ocean. A 27-element hydrophone array with 5 kHz per channel bandwidth is located in the sonar dome all along the wing's leading edge. In addition, it has a four-component acoustic vector sensor in its nose. The two prop-driven AUVs have been equipped with hull-mounted hydrophone arrays with 10 kHz bandwidth for passive synthetic aperture studies, an acoustic vector sensor, and active acoustic imaging systems for ocean bottom-subbottom mapping. Results from the data processing illustrate the tight coupling between acoustic sensor systems, signal array processing methods, and vehicle behavior.

Liberdade, a new class of underwater glider based on a flying wing design, has been under development for the past 3 years in a joint project between the Marine Physical Laboratory, Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington. This hydrodynamically efficient design maximizes the horizontal distance traveled between changes in buoyancy, thereby minimizing average power consumed in horizontal transport to achieve "persistence." The first fully autonomous glider of this class, "XRay," was deployed and operated successfully in the Monterey Bay 2006 experiment. Communications, including real-time glider status reports, were accomplished using an underwater acoustic modem as well as with an Iridium satellite system while on the surface. The payload included hydrophone array, with 10 kHz per channel bandwidth, located in a sonar dome along the leading edge of the 6.1-m-span wing. Narrowband tones from 3.0 to 8.5 kHz were transmitted from a ship-deployed controlled underwater source. During the glider's flight, lift-to-drag ratios (equal to the inverse of the glide slope) exceeded 10/1. However, specific flight behaviors that deviated from this efficient horizontal transport mode allowed for improved detection and localization by the hydrophone array.