摘要
针对有源和无源声呐中的宽带波束形成,提出了一种低旁瓣时域实现方法。声阵列各个阵元的输出首先经过数字延迟线实现数倍采样间隔的时延补偿,然后由FIR数字滤波器来补偿剩余的时延,并实现低旁瓣波束所需的频率加权,最后再把滤波器输出相加得到时域波束输出。FIR数字滤波器的设计采用改进的自适应方法,其期望响应由工作频带划分成的等间隔窄子带上的低旁瓣波束形成权系数构成。各个子带上的低旁瓣波束则采用基于MVDR波束形成原理的波束优化设计方法得到。针对圆弧阵的计算机仿真设计结果和湖上实验验证了本文方法的正确性和有效性。
In modern active and passive sonar systems, broadband digital beamforming for acoustic arrays is widely used to suppress unwanted interference and to detect interested target signals. A broadband low-sidelobe beamforming procedure in time domain is proposed. The first step of this procedure was to delay the outputs of each element in the acoustic array by digital delay lines to accomplish the integer part of the time delay. Then, finite impulse response (FIR) digital filters were used to implement the fractional part of the time delay. The weighting matrix for all array elements at different frequencies for low-sidelobe beam was also implemented with the FIR digital filters. Finally, the outputs of the digital filters were summed up yielding the time domain beam output. The design of low-sidelobe beam patterns and that of the FIR digital filters are two crucial technical issues in this beamforming procedure. We used the improved adaptive approach for the design of FIR digital filters, and the design requirements of these filters were specified by the weights which formed the low-sidelobe beams of each sub-band over the broad frequency band. The low-sidelobe beams of each sub-band were designed using the optimized beam synthesis approach based on the principle of MVDR beamforming. Results of computer simulation and lake-experiment for a twelve-element arc array showed that the beamforming procedure was not only correct but also promising in practical acoustic environment.
出处
《声学学报》
EI
CSCD
北大核心
2003年第4期331-338,共8页
Acta Acustica
基金
国家自然科学基金(69802010)
