Underwater acoustic weak signal detection based on Hilbert transform and intermittent chaos
Underwater acoustic weak signal detection based on Hilbert transform and intermittent chaos
复制标题
基于希尔伯特变换和间歇混沌的水声微弱信号检测
DOI：
10.7498/aps.64.200502
复制
发表时间：
2015-10-20
影响因子：
1
通讯作者：
Chen Xiao
中科院分区：
文献类型：
--
作者：
Chen Zhi-Guang;Li Ya-An;Chen Xiao
本文利用间歇混沌理论分析了混沌振荡器的基本动力学模型，构造了间歇混沌柱，提出了一种检测未知频率的微弱水声信号的有效方法。Duffing振荡器对混沌到间歇混沌的相变敏感，其频率差与驱动力信号和待测信号的频率差略有不同。利用这一理论对海洋背景噪声中船舶信号的频率进行了检测。对于利用间歇性混沌进行检测，没有有效的方法来估计待检测信号的频率，只能通过经验方法来判断，因此会存在人为误差。这些都会影响间歇性混沌的结果，给实际应用带来困难。为了解决这一问题，本文首先研究了混沌系统的基本理论，然后构建仿真信号对系统进行检测，最后对船舶信号进行检测。为了使检测可行，考虑一个混沌振荡器列扫描未知频率的信号。通过这种方法，我们可以得到频率范围。最后利用希尔伯特变换检测间歇混沌的包络，然后利用傅立叶谱测量包络的频率。这样就可以利用描述驱动力信号、船舶信号和包络线之间关系的函数来计算信号的频率。利用该方法对实测声信号进行了仿真和检测处理，能够有效地检测出嵌入在强背景噪声中的船舶信号的频率，并可计算出待检测信号的频率，有利于解决目前存在的频率估计问题。采用希尔伯特变换的方法与仅采用间歇混沌振柱的方法相比，信噪比提高了4.4 dB，验证了本文方法的有效性。
In the paper, we analyse the basic dynamical model of the chaotic oscillator by using the theory of intermittent chaos to construct the column of the intermittent chaos, and present an effective method to detect the weak underwater acoustic signal with an unknown frequency. Duffing oscillator is sensitive to phase transformation from chaos to intermittent chaos, whose frequency difference is slightly different from that between the driving force signal and the signal to be detected. By employing this theory, we detect the frequency of the ship signal in ocean background noise. For the detection by using the intermittent chaos, there exists no effective way to estimate the frequency of the signal to be detected, which can only be judged by empirical methods and therefore the man-made error will exist. All of these will affect the consequence of the intermittent chaos and make the practical application difficult. To solve this problem, in this paper, we first study the basic theory of the chaotic system, then construct the simulated signal to examine the system, and finally detect the ship signal. To make the detection feasible, a chaotic oscillator column is considered to sweep through the unknown frequency of the signal. By using this method, we can obtain the frequency range. Finally Hilbert transform is used to detect the envelope of the intermittent chaos followed by measuring the frequency of the envelope through using Fourier spectrum. Thus the frequency of the signal can be calculated by using the function describing the relationship among the driving force signal, ship signal and the envelope. The simulations and the detection processing of the measured acoustic signal are carried out by using the proposed method, which can effectively detect the frequency of the ship signal embedded within strong background noise and also the frequency of the signal to be detected can be calculated, which is conducive to solving the presently existing problem about frequency estimation. Signal-to-noise ratio can be enhanced by 4.4 dB based on the method by using the Hilbert transform compared with by using the method just through using an intermittent chaotic oscillator column, which verifies the effectiveness of the method in this paper.