Department of Electronic Engineering, Fudan University, Shanghai 200433, China.
College of Physics & Information Technology, Shaanxi Normal University, Xi'an 710062, China.
Ultrasonics. 2014 Jul;54(5):1203-9. doi: 10.1016/j.ultras.2013.10.020. Epub 2013 Nov 11.
Ultrasonic guided wave (GW) assessment of long bone fracture have conventionally been based on pulse excitation. However, the high attenuation during propagation diminishes the amplitude of received GWs and results in low signal-to-noise ratio (SNR). The Barker code (BC) excitation and the optimal binary code (OBC) excitation were utilized in this study to overcome this limitation. Both simulations and in vitro experiments were performed on the fractured cortical bone plate model, and measured signals from both the BC and OBC excitations were decoded using the finite impulse response least squares inverse filter (FIR-LSIF) and then compared with sine pulse (SP) excited signals. The results suggest the efficiency of coded excitation for amplitude and SNR improvement. Furthermore, time-frequency representation (TFR) analysis was applied to experimental signals; with increasing fracture depth, energy transformation between predominate GW modes A1 and S2 was confirmed. These results show the potential of using BC and OBC excitations to evaluate the depth of long bone fracture.
超声导波（GW）评估长骨骨折传统上基于脉冲激励。然而，传播过程中的高衰减会降低接收到的 GW 幅度，并导致低信噪比（SNR）。本研究利用巴克码（BC）激励和最佳二进制码（OBC）激励来克服这一限制。在骨折皮质骨板模型上进行了模拟和体外实验，并使用有限脉冲响应最小二乘逆滤波器（FIR-LSIF）对来自 BC 和 OBC 激励的测量信号进行解码，然后与正弦脉冲（SP）激励信号进行比较。结果表明编码激励在幅度和 SNR 改善方面的效率。此外，时频表示（TFR）分析应用于实验信号；随着骨折深度的增加，GW 主要模态 A1 和 S2 之间的能量转换得到了证实。这些结果表明，BC 和 OBC 激励在评估长骨骨折深度方面具有潜力。
