Real‐time passive localization and spectrum analysis of transient underwater sounds using a field portable computer‐based system

Abstract

This presentation describes the development of a system that provides real‐time determination of the location and spectra of transient underwater sounds. The system is computer‐based and field‐portable. Sound source location is determined by time‐arrival‐difference analysis on sounds detected at a long baseline array of three or more hydrophones. The arrival‐time differences are calculated from digital cross‐correlation analysis of each possible pair of the received pressure time histories. Signal spectra are determined from a Fast Fourier Transform (FFT) analysis. The system was field tested off Point Barrow, Alaska during the Spring 1984 bowhead whale migration as an adjunct to an ongoing visual census effort conducted annually by the North Slope Borough. During this period sounds were received at an array of three sonobouys and transmitted to a nearby field camp for recording and processing. The localization and spectrum analyses were applied successfully to a wide variety of transient sounds including those of bowhead whales, beluga whales, bearded seals, and a variety of ice noises. [This research was supported by the North Slope Borough, Alaska.]