基于单矢量差分能量检测器的扩频水声通信

通过获得扩频处理增益, 直接序列扩频水声通信系统具有较高的稳定性, 是高质量水声通信及远程水声通信的首选通信方式. 但复杂的海洋环境使得直扩系统在解扩时受到载波相位跳变的影响, 这将导致直扩系统的扩频处理增益下降. 为此, 本文针对直扩系统提出了差分能量检测器算法, 通过比较接收端相关器输出能量完成解码, 并与有源平均声强器算法相结合, 提出单矢量差分能量检测器算法. 该算法具有很好的抗载波相位跳变和多途扩展干扰的能力, 并可对信号方位信息实时跟踪估计, 利用估计方位进行矢量组合可获得矢量处理增益, 从而保证直扩系统可以在低信噪比、时变信道条件下稳定工作. 通过仿真分析和大连海试试验, 验证了本文提出的单矢量差分能量检测器算法的有效性和稳健性.

Direct-sequence spread-spectrum underwater acoustic communication based on single vector differential energy detector

By taking advantage of spread processing gain, the direct-sequence spread-spectrum (DSSS) for underwater acoustic (UWA) communication system can be carried out at low signal levels, which is the preferred method for high-quality UWA communication and remote UWA communication. However, phase fluctuation caused by complex marine environment seriously affects the performance of spread spectrum system, leading to the reduction of spread processing gain. Differential energy detector is proposed for DSSS UWA communication system in this paper, which has a good ability of anti-carrier phase fluctuation and multi-path interference by detecting the output energy of two correlators. Differential coding can avoid error propagation when determining the relationship between adjacent symbols. Differential energy detector combined with improved active average sound intensity detector is further proposed in this paper, which can get vector processing gain by updating the estimated azimuth so as to make the system operate stably at a low signal to noise ratio. Improved active average sound intensity detector also has the ability of anti-carrier phase fluctuation, and the feedback code bit information of differential energy detector can ensure that the processing gain of improved active average sound intensity detector is not affected by Doppler's accumulation. Simulation and Dalian sea test have verified the robustness of single vector differential energy detector algorithm. Using the single-vector differential energy detector, good performance is achieved for a signal-to-noise ratio as low as -18 dB based on at-sea data.