摘要
水声信道的典型特点为多普勒频移严重、可利用带宽窄以及强多径干扰。空间分集均衡技术是相干水声通信中克服信道多径干扰,消除码间干扰的一种有效手段。为了极大化地输出阵增益,结合无源相位共轭方法和多通道均衡算法,本文设计了组合信噪干比的全新信道评价方法。利用改进的Sigmoid函数对各通道接收信号的幅度进行加权处理;采用二阶锁相环跟踪各通道信号的相位变化,实现各通道信号同相累加。将各通道低通滤波后的信号能量归一化,采用了分数阶-判决反馈分集均衡器,加入各通道权重系数实现了水声通信系统的分集均衡接收。仿真结果和湖试数据处理结果均表明,优化的幅相加权分集均衡接收算法能抵消多径和噪声的干扰,性能优于等增益合并接收算法。湖试数据处理结果误码率降低了1.8%。
The underwater acoustic channel is characterized as a time-dispersive rapidly fading channel, which in addition exhibits Doppler instabilities and limited bandwidth. To eliminate intersymbol interference causing by multipath propagation, spatial diversity equalization is the main technical means. The paper combines the passive phase conjugation and spatial processing to maximize the output array gain. It uses signal-to-noise-plus-interference to evaluate the quality of signals received at different channels. The amplitude of signal is weighted using Sigmoid function. Second order PLL can trace the phase variation caused by channel, so the signal can be accumulated in the same phase. The signals received at different channel need to be normalized. It adopts fractional-decision feedback diversity equalizer（FDFDE） and achieves diversity equalization by using different channel weighted coefficients. The simulation and lake trial data processing results show that,the optimized diversity receiving equalization algorithm can improve communication system’s ability in tracking the change of underwater acoustic channel, offset the impact of multipath and noise and improve the performance of communication system. The performance of the communication receiving system is better than that of the equal gain combination. At the same time, the bit error rate（BER） reduces 1.8%.
作者
李记龙
黄敏燕
程淑萍
谭倩琳
冯海泓
LI Jilong HUANG Minyan CHENG Shuping TAN Qianlin FENG Haihong(University of Chinese Academy of Sciences Beijing 100049 Institute of Acoustics, Chinese Academy of Sciences Beijing 100190 ShangHai Acoustics Laboratory, Chinese Academy of Sciences Shanghai 200032)
出处
《声学学报》
EI
CSCD
北大核心
2017年第6期685-693,共9页
Acta Acustica
基金
国家自然科学基金项目(6153000187)资助
