基于小波变换的磁定向信号去噪

De-noising of Magnetic Orientation System Based on Wavelet Transform

磁定向信号中畸变噪声的存在严重地影响了磁定向系统的性能。在介绍了磁定向系统工作原理,分析磁定向系统中噪声的产生和特性的基础上,将小波变换的方法应用于磁定向系统去噪,提出用小波软阈值函数对磁定向信号进行去噪处理。首先分析了信号和噪声在小波变换下统计特性的不同点,基于统计特性上的差异,对小波变换后的小波系数进行软阈值函数处理,提取那些模极大值随尺度增大而减小的系数,并保留这些系数,同时滤除模极大值与尺度无关的系数,达到滤除信号中噪声的目的。仿真结果表明:该算法能很好滤除磁定向信号中存在的畸变噪声,使得磁定向信号稳定性得到增强,最终提高了磁定向系统的性能。

The performance of magnetic orientation system is seriously affected by distortion noise.Based on description of working principle of magnetic orientation system and analysis on the production and characteristics of noise in magnetic orientation system,the wavelet transform is introduced into the magnetic orientation system for de-noising.In this paper,the wavelet soft-threshold function is proposed to de-noise the magnetic orientation signal.First,the statistical properties of signal and noise in the wavelet transform are analyzed,and based on the difference of statistical properties,the processing of soft-threshold function on wavelet transform coefficients of signal is done,then those coefficieats with their modulus maxima decreasing with scale increase are extracted and kept,while the coefficients with their modulus maxima having nothing to do with the scale filtered out,thus achieving the purpose of filtering out the noise in the signal.The simulation results show that this algorithm could de-noise the magnetic orientation signal and effectively enhance the performance of magnetic orientation system.