A Wigner based t-ω semblance function for underwater acoustic signal processing

A time evolving spectral pseudosemblance, or coherency, function is proposed. The function relies on auto- and cross-Wigner distribution analysis where the expectation of the Wigner distribution is shown to be equal to the instantaneous power spectral density of a nonstationary signal. Signal returns are modeled as the output of a time-variant random filter through which the time-evolutionary nature of the function is shown to offer a natural extension to the magnitude squared coherency function for stationary signals