Experimental study on amplitude frequency of acoustic signal excited by coupling magneto-acoustic field

Abstract

Object To study the relationship between exciting source characteristic and magneto-acoustic signal, also explore the frequency corresponding relationship between exciting signal and acoustic signal applied on the experimental sample. Methods A practical system has been established to detect magneto-acoustic signal. While single period sine pulse current with different amplitude and frequency were loaded in the sample of straight copper wire, acoustic signal was detected synchronously. Amplitude and frequency of exciting current and acoustic signal were analyzed by using time-frequency method, which was adopted by short time Fourier transform STFT and shifted smoothing rectangle window. Then, comparative study was conducted basing on the processed data. Result Giving the current same frequency as well as different amplitude, linear relationship is obtained between the output amplitude of acoustic signal and current amplitude. However, giving the current same amplitude as well as different frequency, the corresponding frequency spectrum of acoustic signal show different variation law, and thus, there is great difference among the system functions. Conclusion Detecting system is highly sensitive to frequency. In order to acquire more information in the magneto-acoustic signal, both of detecting circuit SNR and acoustic transducer bandwidth should be promoted.