超声信号的小波增强与改进去噪研究  

Research on Improved De- noising and Wavelet Enhancement of Ultrasonic Signal

作　　者：徐钧[1] 周西峰[1] 郭前岗[1] 

机构地区：[1]南京邮电大学自动化学院,江苏南京210046

出　　处：《计算机技术与发展》2015年第2期82-85,共4页Computer Technology and Development

基　　金：国家自然科学基金资助项目(61105082)

摘　　要：预处理技术广泛应用于图像处理领域,文中将预处理技术应用到超声回波信号处理中。传统的阈值函数存在着明显的缺点:硬阈值函数在函数域内存在不连续的问题,软阈值函数去噪后存在恒定偏差。文中提出的改进阈值函数能够弥补硬阈值函数和软阈值函数方法的不足;提出的自适应阈值减小了由小波系数阈值不准确引起的误差。仿真结果表明,经过预处理的信号相比原始信号,信号特征有明显提高;使用改进阈值函数和自适应阈值较传统方法能明显提高去噪的效果,体现在信噪比的提高以及均方误差的减少等方面。The pretreatment technology is widely used in image processing field, in this paper, apply the pretreatment technology to the ul- trasonic signal processing. Traditional threshold treatment has obvious disadvantages. Hard threshold function is discontinuous in its func- tional domain and soft threshold function has the dispersion between the estimated wavelet coefficients. In this paper, the improved thresh- old function can make up the shortage of hard threshold function and soft threshold function. And the adaptive threshold reduces the error caused by threshold values between different wavelet coefficients. Simulation results show that compared with the original signal, the sig- nal after the preprocessing has more obvious signal characteristics, and compared with the traditional threshold function, using the pro- posed threshold function can obviously improve the de-noising effect, which has reflected in the improvement of signal-to-noise ratio and the decrease of mean square error and so on.

关 键 词：预处理 改进阈值函数 自适应阈值 小波去噪 信号噪声比 

分 类 号：TN911.4[电子电信—通信与信息系统]