基于小波分析的振动信号阈值去噪新方法

A new method of vibration signal threshold denoising based on wavelet analysis

传统的软、硬阈值去噪方法在去噪前后小波系数之间分别存在恒定偏差和阈值函数不连续等缺点,达不到对信号去噪的理想效果。针对软、硬阈值函数的优缺点,提出了一种新的阈值去噪函数。在Matlab环境下分别使用3种阈值函数进行去噪实验,对比由3种方法得到的信噪比及均方误差。仿真结果表明,该函数不但具有很好的连续性,而且显著减小了软、硬阈值函数中估计小波系数与真实小波系数间存在的恒定偏差,证实了新阈值函数更加灵活,能更好地消除白噪声干扰。

There exist some shortcomings in traditional soft and hard threshold denoising methods, such as a constant deviation between the wavelet coefficients before and after denoising, and the threshold function is not continuous etc., therefore these methods could not achieve desired denoising effect. A new threshold denoising method is presented based on the traditional hard and soft threshold methods. Denoising experiments are performed by using three threshold functions in Matlab environment. The signal to noise ratio and the size of the mean square error obtained by the three methods are compared. Simulation results show that the new threshold function not only bears good continuity, but also greatly reduces the constant deviation between the estimated wavelet coefficients and the true wavelet coefficients in the soft threshold function,which further confirms that the new threshold function can remove the white noise more flexibly and effectively.