Abstract: A method of and system for monitoring the acoustic transmission conditions in underwater areas using an unmanned, mobile, submersible vehicle of the type including a source of acoustic signals. The submersible vehicle is controlled so that the vehicle traverses a desired path through the water of an area of interest. As the submersible vehicle traverses the desired path, a time-synchronized acoustic signal is transmitted from the acoustic source to at least one receiver spaced from the submersible vehicle so as to generate data representing the acoustic properties of the environment in the water between the acoustic source and the at least one receiver as the submersible vehicle traverses the desired path.

Abstract: Invention relates to a novel method of and system for ranging between an acoustic source carried on an unmanned or autonomous undersea mobile vehicle (UUV or AUV) and preferably a plurality of hydrophone receivers remotely deployed from the vehicle in predetermined patterns, generally suspended from sonobuoys equipped with above-the-sea relay radio transmitting antennas, and with time synchronization provided amongst the source and the receivers, wherein the time delay from the transmissions of the source is measured by utilizing special signal processing, enabling range to be measured in close to real time by determining the product of the sound velocity and the measured time delay, and with the process continually and periodically being repeated throughout the duration of the vehicle run.