Super Resolution Time Delay Estimation for Underwater Acoustic Sinusoidal Signals

A novel hybrid algorithm combing the MODEX (MODE with Extra roots) algorithm and the nonlinear leastsquares (NLS) algorithm is proposed for solving the superresolution time delay estimation problem of underwater acoustic sinusoidal signals. It is assumed that the transmitted signal and the number of paths in the multipath environments are known. The high resolution MODEX algorithm, which was originally proposed for direction of arrival (DOA) estimation in array processing, is modified and used with the NLS algorithm with penalty function to obtain the initial estimates and the true values of the time delays and the amplitudes, respectively. Numerical and experimental results demonstrate the dramatic performance improvement and precision enhancement achieved by the hybrid algorithm relative to classical matched filter method on dealing with the superposition of very closely spaced sinusoidal signals at low SNR values.