Patent ID: 6229761
Filing Date: 2001-05-08
Classification: G01S

Abstract:
A method of estimating a ship's velocity relative to the water and relative to the ground, comprising the steps of:providing a sonar system onboard a ship;operating said sonar system to generate sonar returns;selecting two returns from said sonar returns, said two returns originating from two different directions separated by an angle, each of said two returns including volume reverberation data and bottom reverberation data;selecting said volume reverberation data and said bottom reverberation data from each of said two returns;determining a Doppler shift in frequency for each of said two returns based on said volume reverberation data as a basis for estimating ship velocity relative to the water; anddetermining a Doppler shift in frequency for each of said two returns based on said bottom reverberation data as a basis for estimating ship velocity relative to the ground.