Acoustic sensor arrays used in wind tunnels for acoustic measurements are affected by channel and background noise which can be greater than the signal sources. The noise is mainly related to the wind tunnel parameters, interactions between the wind and the wall, and the acoustic sensor. This study combines channel signal filtering with processing of the cross spectral matrix (CSM) diagonal elements to recover the signal of interest from the channel noise with an extended Kalman filter to track the phase difference of the background noise to optimize the coherent background noise. Simulations show that this method effectively reduces the number of side lobes, suppresses the side lobe level, reduces the influence of noise on the beamforming results, and greatly improves the imaging by the acoustic sensor array.
摘要 风洞中使用声传感器进行声学测量, 通道噪声和背景噪声不可避免, 其强度甚至超过信号源。噪声的存在与风洞工作参数、风与壁面的相互作用以及声传感器选择有直接关系。该文根据噪声产生的原因, 通过通道滤波与处理谱交叉矩阵对角线元素相结合来优化通道噪声, 设计扩展Kalman滤波器渐进跟踪背景噪声相位差来优化相干背景噪声。仿真结果表明：所提出的方法可以有效减少旁瓣数量、抑制旁瓣水平, 减少噪声对波束形成结果的影响, 改善声传感器阵列的成像效果。