【Title】Detection of long bones based on Barker code excited ultrasonic guided waves (2014 No.2) 

【Author】ZHANG Huilin; SONG Xiaojun; TA De'an 

【Abstract】 Single pulse excited ultrasonic guided wave surfers high attenuation during the propagation in long bones. This results in small amplitude and low signal-to-noise ratio(SNR)of measured signals. Thus, the Barker code excitation is introduced into long bone detection to improve the quality of received signals, due to its efficiency in increasing amplitude and SNR. Both simulation and in vitro experiment were performed, and the results were decoded by the weighted match filter(WMF) and the finite impulse response- least squares inverse filter(FIRLSIF),respectively. The comparison between the results of Barker code excitation and sine pulse excitation was presented. For 13-bit Barker code excitation, WMF produced 13 times larger amplitude than sine pulse excitation, while FIR-LSIF achieved higher peak-sidelobe-level(PSL) of —63.59 dB and better performance in noise suppression. The results show that the Barker code excited guided waves have the potential to be applied to the long bone detection.