Surface craft motion parameter estimation using multipath delay measurements from hydrophones

An equation-error (EE) method is described for estimating the three motion parameters of a watercraft (sound source) moving on the sea surface at a constant speed in a constant direction as it transits past a hydrophone located above the sea floor in a shallow water environment, using multipath delay measurements from the hydrophone. The motion parameter estimates are obtained via a linear least-squares (LLS) minimization followed by an algebraic transformation. A weighting matrix is derived for the LLS minimization to reduce the error variances of the motion parameter estimates. Computer simulation results show that the error variances approach the Cramer-Rao lower bounds for small multipath delay measurement errors. The effectiveness of the EE method is demonstrated using real hydrophone data. A method is then described for estimating the linear trajectory of the transiting source using the motion parameter estimates from the individual hydrophones of an underwater acoustic sensor network.