Matched-mode processing schemes of a moving point source

Matched-mode processing schemes are presented to estimate the frequency, velocity, depth, and range information of a time-harmonic point source moving uniformly in stratified oceanic waveguides. Three linear modal filtering approaches (frequency spectral decomposition by a single receiver, spatial spectral decomposition by a horizontal receiving array, and eigenfunction decomposition by a vertical receiving array) are first discussed to provide an overview for possible approaches to localize a moving source. An iterative nonlinear extrapolation algorithm involving only the fast Fourier transform is then employed to reduce the observation time by about an order less than that required by the linear frequency method. Physical insights of the Doppler effect in these inversion procedures are discussed in detail. Based on these insights, practical criteria for choosing processing parameters are established so that they can be applicable to all range-independent waveguides. Numerical results calculated by these methods of both shallow water and deep ocean examples are presented.