Thode A M
Ocean Engineering Department, Massachusetts Institute of Technology, Cambridge 02139, USA.
J Acoust Soc Am. 2000 Oct;108(4):1582-94. doi: 10.1121/1.1289409.
A method is presented for estimating the range of an unknown broadband acoustic source in a waveguide, using a vertical array and a signal sample from another broadband source at a known location relative to the array. The method requires no modeling of the acoustic field, and little to no environmental information for flat bathymetries. Waveguide invariant theory [e.g., D'Spain and Kuperman, J. Acoust. Soc. Am 106, 2454-2468 (1999)] is applied to the "virtual receiver" [Siderius et al., J. Acoust. Soc. Am. 102, 3439-3449 (1997)] to create a "virtual aperture" (VA). In effect, the method effectively converts a source at known range r(g) into a continuum of receivers lying between ranges (1 +/- alpha/beta)*r(g), where beta is a scalar parameter called the acoustic invariant, and alpha approximately 0.1. This effective displacement is achieved by correlating the known source field, measured at frequency component omega, with the unknown source field, measured at frequency component omega + omegas. When the VA output is plotted as a function of omega and omegas, the slope of the resulting correlation contours yields the unknown source range. The concept is illustrated via both simulation and analysis of data collected from a pseudo-random noise source with 75-150-Hz bandwidth during SWellEx-3, a shallow water experiment conducted off the San Diego coast. The virtual aperture can be reformulated for range-dependent environments, if adiabatic propagation assumptions are valid, and if the bathymetry surrounding the array is known.
本文提出了一种方法，用于估计波导中未知宽带声源的距离，该方法使用垂直阵列以及来自相对于该阵列处于已知位置的另一个宽带声源的信号样本。该方法无需对声场进行建模，对于平坦的海底地形，几乎不需要环境信息。将波导不变性理论[例如，D'Spain和Kuperman，《美国声学学会杂志》106，2454 - 2468（1999）]应用于“虚拟接收器”[Siderius等人，《美国声学学会杂志》102，3439 - 3449（1997）]以创建“虚拟孔径”（VA）。实际上，该方法有效地将已知距离(r(g))处的声源转换为位于距离((1 \pm \alpha / \beta) * r(g))之间的一系列接收器，其中(\beta)是一个称为声学不变量的标量参数，(\alpha)约为0.1。这种有效的位移是通过将在频率分量(\omega)处测量的已知声源场与在频率分量(\omega + \omega_s)处测量的未知声源场进行相关来实现的。当将VA输出绘制为(\omega)和(\omega_s)的函数时，所得相关轮廓的斜率给出未知声源的距离。通过对在圣地亚哥海岸外进行的浅水实验SWellEx - 3期间从具有75 - 150 Hz带宽的伪随机噪声源收集的数据进行模拟和分析，对该概念进行了说明。如果绝热传播假设有效且阵列周围的海底地形已知，则可以针对距离相关的环境重新制定虚拟孔径。
