Abstract: Multi-frequency seabed in situ sediment acoustic measurement system developed by the Second Institute of Oceanography , SOA, is the first system of same type in the country. The authors focuse on the primary results on the signal processing of the system. When contaminated by noise, the accurate identification of seabed sediment characteristics will be not easy. From the results of wavelet decomposition from measured signal, it can be found that the signal is similar to itself in different scales, which means that there is little difference in the signal and noise, leading to a hard denoising in frequency domain. Therefore, wavelet transform is applied to denoise signals of the in situ acoustic system. By wavelet method, the signal is decomposed and the wavelet coefficients are calculated. The reconstructed signal reveals true signal.

Key words: multi-frequency in situ sediment seabed acoustic measurement, wavelet transform, signal processing