ABSTRACT
Objective To solve the problem of the low signal to noise ratio (SNR)and limited imaging quality using single pulse exciting method in magnetoacoustic imaging, as well as the limited imaging speed using wave averaging processing method to magnetoacoustic signal. Methods M-sequence coded exciting method was proposed to enhance SNR imaging efficiency. The SNR improvement and sidelobe level were investigated using M-sequence code by simulation and experiments.Results The SNR of magnetoacoustic signal were 19.4,29.6,and 40.4 dB respectively under 7,31 and 127 bit M-sequence coded excitation. Three bits of M-sequence coded excitation magnetoacoustic signals had the integrated sidelobe level being 14.1,10.0 and 7.6 dB,and the peak sidelobe level being 26.3,24.3 and 21.3 dB.In case the SNR was increased by 40 dB,127 bit of M-sequence coded excitation shortened the sampling and procession time from 53.1 s to 0.520 s when compared with singl-pulse excitation combined with waveform average.Conclusion The coded excitation is significant for magnetoacoustic signal SNR and imaging quality improvement.