An underwater target velocity estimation based on cepstrum and autocorrelation for acoustic echo

Due to the target highlights scattering in underwater multipath channels, the underwater target echoes are generally considered as a superposition of sub-echoes, which are represented by different amplitude attenuation factors, time delays and Doppler factors, and the superposition usually degrades the target velocity estimation performance greatly. With a developed multi-highlight target echo model in underwater multipath channels, and based on the great performance of cepstrum and autocorrelation for time delay estimation, a target velocity estimation method is proposed in this paper, where the transmitted signal of the active sonar is designed to be a combined signal. In this method, the received echo is subjected to matched filter first, then the autocorrelation and cepstrum are applied successively to the echo. Since the cepstrum and autocorrelation exist peaks at the same location, they are found to be useful for improving the accuracy of the target velocity estimation. The proposed method is compared with the conventional matched filter method in both simulations and experiments. The results demonstrate that using a lower computational effort, the proposed method can estimate the target velocity more precisely at a lower signal-to-noise ratio.