Abstract: The ultrasonic guided wave (UGW) testing has the problem of the dispersion effect and interference in the transmission medium, which degrades signal-to-noise ratio (SNR) and range resolution in the rail detection. To solve this issue, a Barker-coded excitation technology is applied to UGW rail damage detection. The comparison of the effects of square pulse, sinusoidal pulse, Hanning window sinusoidal pulse waveforms, and carrier cycles on UGW signals is performed by simulation. It is shown that the 10-cycle carrier exhibits the widest main lobe width with a peak-to-side lobe ratio of about －24.0 dB. Field experiments were conducted to validate the findings. The results show that the peak sidelobe level of the ultrasonic guided wave signal excited by Barker coding is －14.40 dB after pulse compression processing, which is 3.26 dB higher than that of a single pulse excitation signal. These findings indicate that ultrasonic-guided wave transmission using the coding excitation technology in the rail environment is reliable.

Key words: coded excitation, ultrasonic guided waves, pulsed compression