Walker Kristoffer T, Zumberge Mark A, Hedlin Michael A H, Shearer Peter M
Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, MC 0225, La Jolla, California 92093-0225, USA.
J Acoust Soc Am. 2008 Oct;124(4):2090-9. doi: 10.1121/1.2968675.
Infrasound arrays typically consist of several microbarometers separated by distances that provide predictable signal time separations, forming the basis for processing techniques that estimate the phase velocity direction. The directional resolution depends on the noise level and is proportional to the number of these point sensors; additional sensors help attenuate noise and improve direction resolution. An alternative approach is to form an array of directional line sensors, each of which emulates a line of many microphones that instantaneously integrate pressure change. The instrument response is a function of the orientation of the line with respect to the signal wavefront. Real data recorded at the Piñon Flat Observatory in southern California and synthetic data show that this spectral property can be exploited with multiple line sensors to determine the phase velocity direction with a precision comparable to a larger aperture array of microbarometers. Three types of instrument-response-dependent beamforming and an array deconvolution technique are evaluated. The results imply that an array of five radial line sensors, with equal azimuthal separation and an aperture that depends on the frequency band of interest, provides directional resolution while requiring less space compared to an equally effective array of five microbarometers with rosette wind filters.
次声阵列通常由几个微气压计组成，这些微气压计之间的距离能提供可预测的信号时间间隔，从而构成了估计相速度方向的处理技术的基础。方向分辨率取决于噪声水平，并且与这些点传感器的数量成正比；额外的传感器有助于减弱噪声并提高方向分辨率。另一种方法是形成一个定向线传感器阵列，每个传感器模拟许多麦克风组成的一条线，这些麦克风能即时整合压力变化。仪器响应是该线相对于信号波前的方向的函数。在南加州派恩平天文台记录的实际数据和合成数据表明，利用多个线传感器可以利用这种频谱特性来确定相速度方向，其精度与更大孔径的微气压计阵列相当。评估了三种与仪器响应相关的波束形成方法和一种阵列反卷积技术。结果表明，与带有玫瑰形风滤波器的五个同样有效的微气压计阵列相比，一个由五个径向线传感器组成的阵列，具有相等的方位角间距且孔径取决于感兴趣的频带，在提供方向分辨率的同时所需空间更小。
