基于分数阶可停振动系统的周期未知微弱信号检测方法

A new detecting method for periodic weak signals based on fractional order stopping oscillation system

本文建立了分数阶可停振动系统,其可停振动状态的改变对周期策动力敏感,对零均值随机微小扰动不敏感,这事实上为周期未知微弱信号检测提供了一种新的高效检测方法和判别标准.与现有的利用混沌系统的大尺度周期状态变化检测周期未知弱信号的方法需逐一尝试设置不同频率内置信号以便期望与待检周期信号发生共振不同,利用分数阶可停振动系统的可停振动状态变化检测周期未知微弱信号的方法,除了同样具有因为状态变化对周期信号的敏感性而能够实现极低检测门限的特点外,还具有混沌系统信号检测所不具有的优点:1)无需预先估计待检信号的周期;2)无需计算系统状态的临界阈值;3)可停振动状态可由本文设计的指数波动函数可靠地进行判断;4)通过系统微分阶数的变化,将检测系统层次化,从而可得到比整数阶检测系统更低的检测门限,特别是在色噪声环境下,通过选取合适的微分阶数,基于分数阶可停振动系统的微弱周期信号检测法能够大幅度的降低检测门限,在本文的仿真试验中,检测门限可达–182dB.

In this paper, a new detecting method for weak periodic signals with unknown periods and unknown forms, the so-called fractional stopping oscillation method, is presented. This new detecting method, which is based on the research of some dissipative system of single degree of freedom, is sensitive to periodic signal—even with unknown period and unknown form—and insensitive to noise. Compared with the known chaotic detections in which a built-in signal must be preset with the same frequency and the same form as the detected periodic signal, the fractional stopping oscillation method can not only be used even at lower SNR than chaotic detection, but also has some other notable advantages as follows： （1） it need not get the period and the form of detected signal before hand or pre-estimate them; （2） it need not pre-calculate the chaotic threshold value; （3） the existence of periodic signal in system input can be reliably and quantitatively judged by volatility index function, designed in this paper, for stopping oscillation method; （4） a more sensitive detection method can be achieved by the fractionalization of the detection system, especially, the detection threshold can reach–182 dB when the background noise is colored Gaussian noise.