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工程设计学报
Chinese Journal of Engineering Design  2008, Vol. 15 Issue (5): 361-364    DOI:
    
Split spectrum processing technique based on wavelet transform
 SHEN  Xiao-An1, YANG  Ke-Ji2
1. Zhexi College, Zhejiang University of Technology, Quzhou 324000, China;
2. Institute of Modern Manufacture Engineering, Zhejiang University, Hangzhou 310027, China
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Abstract  To enhance the signal to noise ratio (SNR) of fundamental ultrasonic echo signals for ultrasonic nondestructive testing (UNDT) and ultrasonic nondestructive evaluation (UNDE)， a new method called split spectrum processing technique based on wavelet transform multi-resolution analysis ability was presented. After the shortcomings and principle of classical split spectrum (SSP) algorithm were analyzed， ultrasonic echo signals were decomposed into sub-bands of constant Q by using wavelet transform multi-resolution analysis ability. Then a signal and noise separator was used to distinguish the target signals from the noises， and the target signals were reconstructed to realize the purpose of enhancing SNR by removing noises. The experiment results indicate that the presented technique has high de-noising performance reliability and improves the SNR enhancing ability for ultrasonic target echo signals contaminated by material noises compared with the classical SSP algorithm．

Key words： UNDT      SNR      split spectrum processing      wavelet transform     
Published: 28 October 2008
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SHEN Xiao-An
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SHEN Xiao-An, YANG Ke-Ji. Split spectrum processing technique based on wavelet transform. Chinese Journal of Engineering Design, 2008, 15(5): 361-364.

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https://www.zjujournals.com/gcsjxb/     OR     https://www.zjujournals.com/gcsjxb/Y2008/V15/I5/361


基于小波变换的裂谱分析法

为了提高超声无损检测（UNDT）和无损评价（UNDE）中基础数据的信噪比（SNR）,提出了一种基于小波变换多分辨率分析的裂谱分析新方法．该方法在分析传统裂谱分析（SSP）方法原理及其局限性的基础上,通过采用小波变换多分辨率分析能力将原始超声回波信号进行等Q子带分解,然后按照一定的信噪分离规则来消除噪声,达到提高信噪比的目的．实验结果表明,与传统裂谱分析方法相比,该方法提高了消噪性能的稳定性,增强了湮没晶粒(或其他散射体)散射中的缺陷回波信号能力．

关键词： 超声无损检测,  信噪比,  裂谱分析,  小波变换 
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