A novel extraction method of doppler frequency with high resolution from ship radiated noise

In order to optimize the poor performance of conventional Wigner-ville distribution (WVD) method concerning frequency resolution and transient tracking in extracting doppler line spectrum from ship radiated noise, a novel WVD algorithm based on Zoom-FFT of frequency shift and Finite impulse response (FIR) filtering in instantaneous correlation function domain was proposed and called Z-IF-WVD. Through Zoom-Fast Fourier Transform (Zoom-FFT) analysis of the frequency-shifted, down-sampled and filtered signal along time direction in instantaneous autocorrelation function (IAF) domain, the performance of Time-frequency distribution (TFD) about cross-term restraint and frequency resolution was effectively promoted. The simulation and experiment results showed that, in contrast to other conventional WVD methods, the proposed algorithm could retain higher frequency resolution and meanwhile restrain cross-terms more effectively of multi-component signals merged in background noise with comparably low Signal-to-noise ratio.