Sensing and Testing Procedures for Underwater Acoustic Array Field Experiments

A low-cost testing procedure is proposed to measure the orientation and range of an acoustic array transmitter at the bottom of the lake or ocean in relation to a surface receiver. Since the GPS measurements are available only on the surface, an inertial measurement unit (IMU) and a depth sensor are used on the transmitter to track the orientation and depth when the transmitter platform is lowered to the deployment position underwater. Procedures for post-experiment data processing are detailed to combine the GPS observations and IMU measurements which yield the locations of the surface receiver relative to the bottom transmitter. Using GPS corrections and long-term stable correction of the IMU sensor, the proposed procedure achieves meter-level accuracy of the localization measurement.