基于自适应加权约束最小二乘法的麦克风阵列稳健频率不变波束形成算法

为了解决麦克风阵列通道失配时波束形成算法的稳健性问题, 提出一种基于自适应加权约束最小二乘法的麦克风阵列稳健频率不变波束形成算法. 该算法在分析无通道失配和通道失配时阵列模型特点基础上, 深入研究了通道失配时约束最小二乘频率不变波束形成算法存在的问题及其产生的原因; 将麦克风特性的概率密度函数作为稳健因子加入到约束最小二乘频率不变波束形成算法后, 其频率不变性的稳健性得到了一定的提高, 但稳健性仍较差. 为了进一步提高约束最小二乘法频率不变波束形成算法的稳键性, 通过定义代价函数中控制频率不变性的动态加权系数来调节旁瓣频谱能量, 大大提高了频率不变波束形成算法的稳键性, 将频率不变的频带范围内同一到达角度上不同频率所形成的阵列响应的最大值与最小值之比定义为波动误差, 并作为比较本文算法与约束最小二乘稳健波束形成算法和minmax稳健波束形成算法在通道失配时频率不变性稳键性的评价指标. 算法实例验证结果表明, 在麦克风阵列通道失配时, 本文算法的波动误差最小、频率不变波束形成稳健性最好, 而且适用于任意结构的阵列.

Adaptive weighted constrained least squares algorithm based microphone array robustness beamforming algorithm

In order to solve the problem of robustness of beamforming algorithm with microphone array channel mismatch, an adaptive dynamic-weighted constrained least square algorithm-based microphone array robustness frequency invariant beamforming algorithm is proposed. In the proposed algorithm, by analyzing the microphone array model, with or without channel mismatch, the disadvantages of the constrained least square frequency invariant beamforming algorithm with channel mismatch are studied. After the probability density functions of the microphones are defined as the robustness factors and added to the constraint least square frequency invariant beamforming algorithm, the robustness is improved to a certain extent, but it is still poor. In order to further improve the robustness of the algorithm, dynamic-weighted coefficients for controlling frequency invariance in the cost function are used to regulate the sidelobe spectrum energy. The fluctuation error is defined as the ratio of the maximum to minimum value of array response formed by the same angle of arrival at different frequencies, within the frequency range of frequency invariant, to compare the proposed algorithm with the constrained least square robustness frequency invariant and minmax robustness broadband beamforming algorithm. Experimental results of the algorithms show that the fluctuation errors of the proposed algorithm are the smallest and its robustness is the best; it can effectively overcome the poor robustness of the beamforming algorithm caused by microphone array channel mismatch, and can be applied to any arbitrary array structure.