时频分布的弱信号检测技术的研究及其应用

双线性时间-频率变换在时间域与频率域都具有较高的分辨率,有利于复杂背景条件下微弱瞬时信号的探测。研究发现,频谱图的分辨率较低,W igner-V ille分布存在很强的交叉项,不适合瞬时信号的检测。Cho i-W illiam s分布存在频率混叠及信息丢失现象,检测效果也不理想。提出了一种无混叠时频分布,能够避免CW D中的信息丢失,有效抑制交叉项,而且具有较高的分辨率。通过数字仿真与齿轮箱故障检测实例,证明新的时频分布能够有效检测复杂信号中的瞬时分量。

Research on the weak signal detection technique and application based on time-frequency distribution

Bilinear time-frequency transform possesses a high resolution both in the time domain and the frequency domain.It can be utilized to detect weak transient signal in complex background.It is found that the spectrogram is of low resolution,and strong cross-terms exist in Wigner-Ville distribution and frequency aliasing and information loss appear for in Choi-williams distribution.Thus,one cannot achieve satisfied transient signal detection by using the foregoing two distributions.Based on the analysis of exponent distribution,this paper presents a novel alias-free time-frequency distribution which can avoid the information loss in CWD while suppressing the cross-terms.Moreover,this distribution has a very high resolution.Digital simulation and gearbox fault diagnosis experiments are used to prove a fact that the new distribution can effectively detect transient components in complex signals.