海豚Whistles为信息载体的正交频分复用循环移位键控扩频伪装水声通信

Orthogonal frequency division multiplexing cyclic shift keying spread spectrum camouflaging underwater acoustic communication with dolphin whistles as information carrier

提出一种伪装水声通信调制方法,将原始海豚whistles信号表示为以自身DFT系数为数据符号的正交频分复用（OFDM）块,采用m序列对OFDM块中的子载波幅度进行指数调制实现正交频分复用循环移位键控（OFDM-CSK）扩频调制,分别采用PEAQ算法与相关系数计算听觉与波形相似度,作为两个客观评价结果约束OFDM子载波幅度的修改程度,保证伪装的效果。提出匹配滤波与正交匹配追踪结合的自同步算法,使伪装通信信号帧结构的设计保持原始whistles叫声的模式,提高了伪装的效果。通过CSK扩频技术很大程度地提高系统的频带利用率且通过垂直阵虚拟时间反转信道均衡技术提高了通信系统的稳健性。海上试验验证了伪装通信方法的可行性。

A camouflaging modulation method is proposed. The original whistle is represented as orthogonal frequency division multiplexing （OFDM） blocks by using DFT coefficients. The m-sequence is used to modulate the subcarriers of OFDM signal by using the orthogonal frequency division multiplexing cyclic shift keying （OFDM-CSK） spread spectrum technology. The PEAQ algorithm is used to compute the similarity in auditory aspects and the correlation coefficient is used to compute the similarity in waveform, which are as two metrics to evaluate the camouflaging effect. In addition, a self-synchronization method that combines the correlation and OMP algorithm is proposed and hence the frame structure of transmitted signal could be designed as same as the origin whistles, which would improve the camouflaging performance. The bandwidth efficiency of the system is improved by using CSK spread spectrum technology and the robustness of the system is improved by using the vertical time reversal equalization technique. The experiment results verify the feasibility of the proposed camouflaging communication method