海洋波导中刚性球及旋转椭球前向散射场时频特征的畸变

利用波导中目标声散射理论的简正波方法,数值模拟了自由空间和浅海均匀波导中刚性球、旋转椭球的散射场,分析了波导中刚性体前向散射时频特征的畸变规律。仿真结果表明:波导中刚性体的前向散射时域波形与频谱特征受波导制约;目标散射场的固有特征受波导色散特征的调制,时频谱上呈现出由于色散的简正波间的耦合而导致各简正波能量条纹界限模糊的现象。时频特征的畸变程度与组成散射共振系统的波导、目标的尺度以及散射体布放深度有关,随波导底质透声能力和深度增加、散射体散射强度(信混比)增强而减弱。

Distortion of time-frequency characteristics of forward scattering from a rigid sphere/prolate-spheroid in an oceanic waveguide

By using of the normal mode method of the acoustic scattering theory, the time-frequency characteristics of forward scattering from a rigid sphere or prolate-spheroid in the oceanic waveguide and the free space situation are simulated, and the distortion of time-frequency characteristics of forward scattering from a rigid target in an oceanic waveguide is analyzed. The simulation results show that the temporal waveform and the spectrum characteristics of forward scattering from a rigid target in a waveguide are restricted by the properties of waveguide, and the inherent characteristics of the target scattering field are modulated by the waveguide dispersion. The "stripe" on the time- frequency spectrum becomes indistinct due to the coupling of dispersive normal modes. The level of the time-frequency characteristic distortion is controlled by scales of the waveguide and target, of which the resonant system consists, and target depth in the waveguide. The distortions would be weakening with the increases of sound transmission ability of bottom and waveguide depth, so does the target scattering strength.