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Method of measuring ultrasonic wave transmission time by using chirp signals

A technology of linear frequency modulation signal and propagation time, which is applied to the analysis of solids using sound waves/ultrasonic waves/infrasonic waves, etc., which can solve the problems of low efficiency, long time, and low accuracy, and achieve high efficiency, short method cycle, and reduced calculation.

Inactive Publication Date: 2015-09-09
ZHEJIANG FORESTRY UNIVERSITY
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Problems solved by technology

As a result, the entire process of implementing the method takes a long time, has low efficiency, and low accuracy

Method used

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  • Method of measuring ultrasonic wave transmission time by using chirp signals
  • Method of measuring ultrasonic wave transmission time by using chirp signals
  • Method of measuring ultrasonic wave transmission time by using chirp signals

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Embodiment

[0051] First, the excitation signal is generated by the linear frequency modulation signal generator, and the excitation signal is amplified by the power amplifier to excite the transmitting transducer to emit ultrasonic waves, and the emitting ultrasonic waves are u x (t), Let A=100v,f 0 =1.15MHz, B=2.1MHz, T=50us, at this time, ultrasonic waves are emitted x The spectrogram of (t) is as follows image 3 as shown, Figure 3-1 Indicates the ultrasonic signal u x The amplitude of (t) changes with time, the time unit is us, Figure 3-2 Indicates the ultrasonic signal u x The amplitude of (t) varies with the ultrasonic signal u x (t) frequency change law, the frequency unit is MHz;

[0052] Then send the ultrasonic signal u x (t) After passing through a wooden board with a thickness of 6mm, it reaches the receiving transducer. The amplitude of the ultrasonic signal received by the receiving transducer is attenuated at this time, and the phase is delayed. The spectrum dia...

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Abstract

The invention discloses a method of measuring ultrasonic wave transmission time by using chirp signals. The method comprises the following steps: an excitation signal is generated by a chirp signal generator to excite a transmitting transducer to transmit ultrasonic wave, after passing through a material to be measured, a transmitted ultrasonic wave signal is received by a receiving transducer, then wavelet filtering processing is performed, afterwards, an ultrasonic wave signal is moved leftwards, the processed ultrasonic wave signal is multiplied by the transmitted ultrasonic wave signal to obtain a product signal, Fourier transform is performed on the product signal to obtain magnitude spectra of the product signal, the frequency of a peak value in the magnitude spectra is determined by using a maximum value function, and finally the transmission time of the ultrasonic wave in the material to be measured is calculated. According to the method, fast Fourier transform (FFT) and signal multiplication are performed only once, the operation burden is greatly lowered, and thus the method is short in implementation period and high in efficiency; by using chirp signals to excite ultrasonic pulse, the ultrasonic penetrability and the time resolution of ultrasonic detection are improved, and thus the detection accuracy rate is improved.

Description

technical field [0001] The invention relates to a method for measuring ultrasonic propagation time in the technical field of ultrasonic nondestructive testing, in particular to a method for measuring ultrasonic propagation time by using a chirp signal. Background technique [0002] Ultrasound is one of the most widely used methods in non-destructive testing. In ultrasonic non-destructive testing, the commonly used method is to measure the speed of the material to be tested based on the propagation time or propagation speed of the ultrasonic wave in the material to be tested (equal to the propagation distance divided by the propagation time). Dynamic Young's modulus, density, moisture content, cracks and holes, etc., because this method has the advantages of simple implementation and convenient use, it has been widely used, so it is very important to accurately measure the propagation time of ultrasonic waves in the material to be tested academic and practical significance. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/07
Inventor 蔺陆军方益明李剑冯海林
Owner ZHEJIANG FORESTRY UNIVERSITY
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