摘要
以环绕在刚性圆柱体上的均匀圆阵为阵列模型,分析了刚性圆柱体对圆阵响应的影响,在声场分解所得到的相位模式空间,推导了相位模式波束形成阵列和延迟求和波束形成阵列的白噪声增益和指向性指数的定量表达式,分析了它们在不同频率段的变化规律。在存在和不存在刚性圆柱体两种情况下,对两种阵列性能进行了对比分析。研究了圆阵与圆柱体之间存在间隙时对阵列接收信号及阵列性能的影响。仿真结果表明,在两种情况下相位模式波束形成处理都具有频率不变的指向性,但在低频段牺牲了阵列的鲁棒性;延迟求和波束形成处理在整个频率段具有较好的鲁棒性,但随频率的降低其波束指向性下降,直至变成各向同性阵列。存在刚性圆柱体时,两种阵列鲁棒性均有了一定的提高,前者的指向性不变,而后者的指向性得到了提高。圆阵与圆柱体之间的间隙会降低阵列在高频段的鲁棒性。
The influence of a rigid cylindrical baffle on a uniform circular microphone array （UCA） response is analyzed based on the array model of a UCA mounted on a rigid cylindrical baffle. In the phase mode space derived from the decomposed sound field, expressions of white noise gain （WNG） and directivity index （DI） for phase mode and delayand-sum beamforming array are derived after some algebraic manipulations. The relationship between WNG and DI with frequencies is analyzed. The WNG and DI of phase mode beamforming array are compared with those of delayand-sum beamforming array using UCA with and without the rigid cylindrical baffle respectively. The influence of offset between UCA and cylinder on the array received signals and array performance is studied. Computer simulations demonstrate that under two conditions the phase mode beamforming array has frequency-independent directivity, which is achieved at the cost of reduced robustness at low frequency, and the delay-and-sum beamforming array has constant WNG throughout the whole frequency range, while the DI is reduced at low frequency until it becomes an omidirectional array. Both of the WNG of two kinds of array are improved when there is a rigid cylindrical baffle and the former＇s DI is unchanged while the latter＇s DI is increased with a certain extent. The offset between the UCA and the cylinder can reduce the robustness of the array at high frequency.
出处
《声学学报》
EI
CSCD
北大核心
2010年第1期68-75,共8页
Acta Acustica
