Barker码激励超声导波在长骨检测中的应用

单脉冲激励的超声导波在长骨中传播时,信号的衰减大,导致接收信号的幅度很小,且噪声严重。Barker码激励能有效增大接收信号幅度,提高信噪比(SNR)。将其应用到超声导波长骨检测中,进行仿真和长骨实验,得到的信号分别用加权匹配滤波器和有限冲激响应-最小均方误差(FIR-LS)逆滤波器进行压缩,并与单脉冲激励的结果进行了对比。结果表明,对于13位的Barker码,采用加权匹配滤波器进行解码时,压缩信号幅度是单脉冲激励接收信号的13倍;而FIR-LS逆滤波器则达到-63.59 dB的峰值旁瓣水平(PSL),更好地抑制噪声。说明可以将Barker码激励超声导波应用于长骨的检测中。

Application of Barker code excited ultrasonic guided waves to long bone detection

Single pulse excited ultrasonic guided waves suffer high attenuation during the propagation in long bones. This results in small amplitude and low signal-to-noise ratio (SNR) of measured waveform. Barker code excitation is introduced into long bone detection, because of its efficiency in increasing amplitude and SNR of received signals. Both simulation and long bone experiment had been done, and the results were compressed by weighted match filter and finite impulse response least squares (FIR-LS) inverse filter, respectively. The comparison between the results of Barker code excitation and single pulse excitation was presented. For 13 bits Barker code excitation, weighted match filter produced 13 times larger amplitude than single pulse excitation, while FIR-LS inverse filter achieved higher peak-sidelobe-level (PSL) of -63.59 dB and performed better in noise suppression. The results show that the Barker code excited ultrasonic guided waves have the potential to be applied to the long bone detection.