基于混沌理论的频率未知的微弱信号的检测方法研究

发布时间：2018-04-21 19:44

本文选题：混沌 + 微弱信号　；参考：《东北大学》2013年硕士论文

【摘要】：微弱信号的检测在雷达、声纳、振动测量、故障诊断等领域有着非常广泛的应用。国际上,随着微电子技术和非线性检测理论的发展,故障诊断技术也得到了快速的发展,但在国内关于微故障信号检测研究尚需大量投入,加强具有自主知识产权技术的创新开发及科研成果的转化已成为迫在眉睫的问题。本文针对化工流体管道微泄漏检测、机械疲劳振动故障预报等问题,利用混沌系统相轨迹状态从混沌态到大尺度周期态的跃迁对于输入微弱信号的敏感特性,提出了针对频率未知微弱信号的分段测频检测方法以及基于复合系统的微弱信号检测方法,实现了对淹没在强噪声中的频率未知的微弱信号的检测,为保障工业过程的高效稳定运行提供基础理论与技术支持。本文做了如下研究：首先,详细研究了单Duffing系统和双耦合Duffing系统的检测原理,并对比分析了在不同噪声等级下两个系统能够检测的微弱信号的信噪比门限。仿真结果证明双耦合Duffing系统比单Duffing系统具有较强的抗噪性能。然后,针对微弱信号检测的难点问题,利用混沌系统的间歇混沌特性,提出了一种基于双耦合Duffing振子的未知频率的微弱信号的分段测频检测方法,并详细阐述了该方法的定义以及检测原理。通过一系列仿真实验证明该方法在不同噪声等级下能够准确的检测出任意周期信号的频率。最后,详细研究了相关方法和双耦合Duffing系统在微弱信号检测方面的优势和劣势,并结合这两种方法提出一种针对未知频率微弱信号检测的复合系统,将互相关方法和基于双耦合Duffing振子的分段测频检测方法结合起来,充分发挥各自的优势。仿真实验证明该方法能够更好的将待测周期信号从强噪声中提取出来,大大的降低了待测信号的信噪比门限。
[Abstract]:Weak signal detection is widely used in radar, sonar, vibration measurement, fault diagnosis and so on. In the world, with the development of microelectronic technology and nonlinear detection theory, fault diagnosis technology has also been rapidly developed, but the research on micro-fault signal detection still needs a lot of investment in our country. It has become an urgent problem to strengthen the innovation and development of independent intellectual property technology and the transformation of scientific research results. In this paper, aiming at the problems of micro-leakage detection and mechanical fatigue vibration fault prediction in chemical fluid pipeline, the sensitive characteristics of phase locus state transition from chaotic state to large-scale periodic state for input weak signal are used in this paper. In this paper, a frequency detection method for unknown weak frequency signals and a weak signal detection method based on composite system are proposed to detect weak signals with unknown frequency submerged in strong noise. It provides basic theory and technical support for ensuring the efficient and stable operation of industrial process. This paper has done the following research: firstly, the detection principle of single Duffing system and double coupling Duffing system is studied in detail, and the signal-to-noise ratio threshold of weak signal can be detected by two systems under different noise levels is compared and analyzed. The simulation results show that the dual coupling Duffing system has better noise resistance than the single Duffing system. Then, aiming at the difficult problem of weak signal detection, using the intermittent chaos characteristic of chaotic system, a frequency detection method of weak signal based on the unknown frequency of dual-coupling Duffing oscillator is proposed. The definition and detection principle of this method are described in detail. Through a series of simulation experiments, it is proved that the method can accurately detect the frequency of arbitrary periodic signals under different noise levels. Finally, the advantages and disadvantages of correlation method and double coupling Duffing system in weak signal detection are studied in detail, and a composite system for weak signal detection with unknown frequency is proposed combining these two methods. The cross-correlation method and the segmented frequency measurement method based on dual-coupling Duffing oscillator are combined to give full play to their respective advantages. The simulation results show that the proposed method can extract the periodic signal from the strong noise and reduce the signal-to-noise ratio (SNR) threshold of the signal to be measured.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TN911.23;O415.5

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