Patent ID: 9013959
Filing Date: 2015-04-21
Classification: G01S

Abstract:
1. A method for determining a geophysical position of an object in an underwater channel, the method comprising: receiving, by the object, acoustic signals from at least two sources, each received acoustic signal including one or more waveguide modes associated with the underwater channel excited by a frequency of the respective acoustic signal transmitted through the underwater channel, the acoustic signals being transmitted at respective predetermined transmission times; identifying a waveguide mode among the one or more waveguide modes in the received acoustic signals; determining a modal group velocity corresponding to the identified waveguide mode, based on a sound speed profile of each source and a frequency of the identified waveguide mode from the received acoustic signals; determining an arrival time for the identified waveguide mode from the received acoustic signals, based on the respective predetermined transmission times; and determining the geophysical position based on the arrival time of the identified waveguide mode and the modal group velocity for the identified waveguide mode.