Time delay estimation via zero-crossing of envelope

Time-delay estimation of an acoustic signal in an ocean waveguide is a challenging due to the received signal corrupted by noise and phase distortion caused commonly by reflection of the transmitted signal traveling to a remote receiver via more than one path. In this study, envelope-based Hilbert transform method is applied to enhance the accuracy of time-delay estimation. Through the mathematical interpretation and numerical simulations, the proposed method is compared to the conventional time-delay estimation methods (e.g., cross correlation and zero-crossing of Hilbert transform). It is found that the envelope-based Hilbert transform method more efficiently estimates the time-delay than the conventional methods and resolve ambiguity of time delay estimate.