Estimation of clock drift in underwater acoustic instruments using propagation channel analysis

Abstract

All underwater acoustic sensors require accurate on-board clocks for subsequent data analysis and interpretation. Unfortunately, most clocks suffer from a phenomenon called “clock drift” (loss of accuracy), which occurs due to environmental changes, aging, and other factors. Typically, the clock drift is accounted for by calibrating the clock in the instrument before and after the deployment, and applying a correction during data post-processing. This method, however, does not allow accurate estimation of clock errors during a particular experimental event. In this presentation a small subset of data collected on the last day of the Bottom Seismometer Augmentation in the North Pacific (OBSANP) Experiment in June-July 2013 is analyzed. It is shown that advanced signal processing techniques can be used to accurately reconstruct the motion of the ship-suspended acoustic source, which, in turn, can improve the accuracy of the acoustic receivers deployed on the seafloor in the deep ocean. [Work supported by the MITRE Innovation Program and ONR.]