Patent ID: 6704246
Filing Date: 2004-03-09
Classification: G01S

Abstract:
A method for acoustic mapping using buoys dispersed throughout a maritime zone, the buoys including active buoys for transmitting distinct signals that echo off a target and are received by at least two of the buoys, the distinct signals being forwarded to a processing base to extract signal information, the processing base compiling an Active Geographic Plot (AGP) providing a geographical representation of a position of the target and an estimate of a velocity of the target, the method providing for a successive determination of the position and the estimate of the velocity and comprising the steps of:(a) producing a grid of cells for a zone of possible presence (ZPP); (b) creating blind elliptical zones by deleting signals corresponding to direct paths between transmitting and receiving buoys; (c) determining an amplitude and azimuth of a cell; (d) calculating a likelihood index of the cell; (e) first looping of steps (c) and (d) over all cells of the ZPP; (f) calculating a neutral index of a cell; (g) second looping of step (f) over all cells of the ZPP; (h) normalizing by the neutral index and then performing a base adjustment; (i) third looping of step (h) over all cells of the ZPP; (j) multiplying the likelihood indexes associated with independent observations of various buoys; (k) fourth looping of step (j) over all cells of the ZPP; (l) fifth looping of steps (c)-(j) over the independent observations; and (m) thresholding of the positions to obtain a number of noncontiguous contacts forming an AGP chart of the positions.