Patent ID: 6525994
Filing Date: 2003-02-25
Classification: G01S,G01V

Abstract:
A method for locating, in three-dimensional space and in relation to a predetermined location, an object emitting acoustic signals comprising the steps of:deploying an array of acoustic transducers; receiving acoustic signals at said deployed array including the acoustic signals from the object; estimating a bearing from the predetermined location to the object in response to the received acoustic signals, said estimating including inverse beamforming processing the signals from each transducer in said deployed array using different frequencies and multipath analysis of said received acoustic signals; repeatedly generating beam values for acoustic signals received by said deployed array from different incremental locations at incremental ranges and depths along the estimated bearing whereby bearing, depth and range information are provided as a function of time and a correlation value is obtained for each acoustic frequency and for each incremental location; selecting an individual incremental location with a peak beam value based upon an inverse beamformer twenty-six nearest neighbor peak picker analysis comprising the steps of; determining the center frequency of the received frequencies; segmenting the received frequencies into n frequency bins greater than and less than the determined center frequency; calculating the left half bandwidth of the peak beam values received for frequency bins less than the center frequency until the left half bandwidth BWLn becomes zero or negative; calculating the right half bandwidth of the peak values received for frequency bins greater than the center frequencies until the right hand bandwidth BWRn becomes zero or positive; adding the calculated left half bandwidth BWLn to the calculated right half bandwidth BWRn to obtain the total bandwidth, BW, said total bandwidth defining said selected individual incremental location; and providing bearing, range and depth information from the predetermined location to the selected incremental location thereby locating the object in three-dimensional space.