The application of time entropy of lift wavelet on ultrasonic signal detection
Enjun Yu, Tingkai Zhao, Qingwei Ye · 2011
T Ultrasonic signal detection is one kind of the non-destructive testing methods, and it can be non-destructive inspection of the internal defects of materials or mechanical components. One of the difficulties of ultrasonic signal detection is the detection of the echo signal in the ultrasonic signal. Firstly, the basic principle of lifting wavelet transform and the theory of integer lifting wavelet transform of ultrasonic signal is introduced in this paper. Then the wavelet-time entropy algorithm is introduced and the numerical simulations are carried out to prove the feasibility of this algorithm in abnormal signal detection. An improved wavelet-time entropy algorithm is put forward in this paper. The high-frequency coefficients of wavelet transform are replaced by the low-frequency coefficients, and the optimal width of window is worked out for actual ultrasonic signal. The results show that this improved wavelettime entropy algorithm can effectively detect the echo signal in ultrasonic signal.