Synthesis and Modification of Cetacean Tonal Sounds for Underwater Bionic Covert Detection and Communication

For most conventional bionic signal design methods, they cannot construct high-similarity bionic signals to match those complex cetacean sounds because they are only based on relatively simple bionic signal models. Besides, although very few methods based on the weighted signal superposition technology can construct high-similarity bionic signals, it's very difficult to adjust relevant parameters to match different cetacean sounds or synthesize other desired bionic signals. To solve these problems, firstly, two bionic signal models are proposed individually to mimic cetacean sounds with a simple time-frequency (TF) structure, and then they are combined to mimic cetacean sounds with complex TF structures based on a designed piecewise construction strategy. Based on the two models, the parameters of the synthesized bionic signals can be adjusted to improve detection and communication performance of the bionic signals. The experimental results show that the Pearson correlation coefficient (PCC) results between 13 true cetacean sounds and their corresponding bionic signals are higher than 0.97, and 11 results of them are no less than 0.99. Four key performance indicators of a bionic signal are improved by more than 40% when bandwidth increases by 1kHz. Experimental results demonstrate that the proposed method cannot only efficiently imitate all kinds of simple and complex cetacean tonal sounds with high similarity, but also construct a variety of the same type of bionic signals by simply adjusting model parameters. In addition, the proposed method can also be applied to other areas, such as constructing a new cetacean sound database and so on.