Underwater Acoustic Positioning System

Sonatech proposes to develop the operational concept for an underwater "GPS-type" acoustic positioning system (UAPS) deployable from surface craft or helicopter, providing multiple users the ability to navigate with GPS precision underwater. UAPS has application for unmanned underwater vehicles (UUV), SEAL delivery vehicles (SDV), and diver-held Hydrographic Mapping Units (HMU) and Underwater Imaging Systems (UIS). UAPS will consist of a field of autonomous acoustic transponder sensors transmitting periodic time-synchronized spread spectrum signals. Following deployment, the transponder array will automatically self-calibrate to establish precise transponder XYZ positions. User equipment will passively monitor transponder transmissions, and convert time differences of arrival to XYZ positions in real time with an accuracy of better than 2 meters. Each transponder will transmit its own position data periodically, so users need no prior knowledge of array placement parameters. Once transponders are deployed, no further surface presence or equipment is needed for system calibration or operation. Phase I investigations include: a. Detailed definition and design of all acoustic signals required b. Determination of the optimum method of transferring transponder coordinates to user equipment via acoustic telemetry. c. Define optimum battery chemistry and electronics package size to support all performance requirements while minimizing physical size and handling requirements.