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.