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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。
Single-pulse excitation of the ultrasonic guided wave propagation in long bones, the signal attenuation, resulting in the received signal amplitude is small, and the noise is serious. Barker code excitation can effectively increase the received signal amplitude, improve signal-to-noise ratio (SNR). The proposed method was applied to the ultrasonic guided-wave long bone test, and the simulation and long-bone experiment were performed. The obtained signals were compressed by a weighted matched filter and a finite impulse response-least mean square error (FIR-LS) The results of pulse excitation are contrasted. The results show that for the 13-bit Barker code, the amplitude of the compressed signal is 13 times that of the one-pulse excitation using the weighted matched filter, and the peak-sidelobe level of -63.59 dB for the FIR-LS inverse filter PSL) to better suppress noise. Description Barker code can be used to guide the ultrasonic guided wave detection of long bones.