Performance and limitations of spectral factorization for ambient noise sub-bottom profiling
Performance and limitations of spectral factorization for ambient noise sub-bottom profiling
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DOI：
10.1121/1.2048967
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发表时间：
2005-10
影响因子：
2.4
通讯作者：
C. Harrison
中科院分区：
文献类型：
--
作者：
C. Harrison
利用垂直漂移阵列作为测量噪声方向性的手段，可以推断出反射系数随角度和频率的变化。这可以转换为时变脉冲响应，即，亚底部轮廓，通过使用频谱分解来恢复相位。通过仿真和实验讨论了该技术的局限性。首先，光谱分解提供了给定光谱脉冲响应的最小相位实现，而真实反射系数实际上可能不是最小相位。其次，由阵列长度决定的光束宽度会略微模糊反射系数特征的干涉条纹。频率分辨率的降低降低了可以检测到的层的最大深度。详细的机制的考虑导致了一种方法，提高频率分辨率，从而最大深度。除非水和上层之间的阻抗对比非常小，否则光谱分解往往能很好地发挥作用。
Using a drifting vertical array as a means to measure noise directionality one can infer reflection coefficient vs angle and frequency. This can be converted to a time-varying impulse response, i.e., a sub-bottom profile, by using spectral factorization to recover the phase. Limitations of the technique are discussed with simulations and experiment. First, spectral factorization provides a minimum phase realization of the impulse response for the given spectrum, whereas the true reflection coefficient may not actually be minimum phase. Second, the beam width, determined by array length, slightly smudges the interference fringes that are characteristic of the reflection coefficient. This reduction in frequency resolution reduces the maximum depth to which layers can be detected. Consideration of the detailed mechanism leads to a way of improving frequency resolution and hence maximum depth. Spectral factorization tends to function well unless the impedance contrast between water and upper layers is very sm...