基于分数阶傅里叶变换的水下目标宽带回波精确提取

线性调频信号可能将成为水下目标强度宽带测试的一种主要信号形式。本文在分析水中目标回声构成特点的基础上,探讨了一种滤除界面反射精确提取目标回波的方法。利用线性调频信号在一定分数阶傅立叶域呈现高度聚集的特性,将线性调频信号作为收发合置换能器的发射信号,在适当的分数阶傅立叶域中,目标回波和界面反射波如果表现为两个可分离的谱峰,就可以用窄带滤波的方法去除界面反射。本文给出了算法仿真及水池试验结果,即使对于和线性调频回波相距很近的界面反射,仍然可以有效去除,精确提取出目标回波。

Accurate pick-up of underwater object's broadband echo based on fractional Fourier transform

LFM signal will likely become the main signal form in underwater target strength broadband test. After reviewing the echo structural characteristics of the underwater target, a method to accurately pick-up the direct wave separated from the surface-reflected wave is discussed. Using the fact that a LFM signal shows high time and frequency congregation in some fractional Fourier domain, when a LFM signal is transferred into certain fractional Fourier domain, it can become single frequency sine signal and the interface reflection can be wiped off by narrow band filter. Emulation and tank test signal process results confirm that the proposed method does work even in the case that very near interface reflection is presented.