Underwater reverberation suppression based on non-negative matrix factorisation

Reverberation is the main background interference in underwater active sonar target de-tection that seriously interferes with the extraction of the target highlight echo. In con-sideration of the difference in the time-frequency distributions of the target highlight echo and reverberation, an underwater reverberation suppression method based on non-negative matrix factorisation is proposed in this study. The Wigner-Ville time-frequency matrix of the underwater target echo is used as the input, and non-negative matrix fac-torisation is applied to express the time-frequency matrix as a low-rank matrix. The in-fluences of rank selection on the reverberation suppression effect and signal expression of the target highlight echo are analysed. Given that the time-frequency matrix of the target highlight echo cannot be expressed in the low-rank form when transmitting linear fre-quency modulation signal, this matrix is processed with low-rank preprocessing through matrix rotation. The components of the target highlight echo, which can be expressed in the form of a low-rank matrix, are preserved. By contrast, the components of the reverber-ation interference, which cannot be represented in such a form, are removed in the under-water target echoes. The simulation and experimental results show that the algorithm can effectively im prove the signal-to-reverberation ratio of underwater target echoes. (c) 2021 Elsevier Ltd. All rights reserved.