Abstract:In order to increase the amplitude of the ultrasonic guided wave (UGW) signal at the receiving end of the rail and improve the identification of the guided waves, the coded excitation technique is applied to UGW broken rail detection system in this paper. At the transmitters, the system uses a long duration 13-bit Barker-coded to generate UGW excitation signal. At the receivers, the matched filtering method is used to make pulsed compression of the echo signal. In this paper, the simulation analysis and experimental verification on 1 meter 60 type rail are carried out. The results show that the experimental results are in good agreement with the simulation results. The signal amplitude of Barker code excitation after pulsed compression by matched filtering is much higher than the received signal of single pulse excitation, compared with the received signal of the single pulse excitation, the amplitude of the Barker code excitation received signal increases to more than three times of that. The normalized waveforms of the two signals are almost completely coincident in the time domain, the similarity between the two signals in the simulation and experiment results is reached 99. 39% and 99. 29% respectively. The conclusion can be drawn that using Barker code as excitation to obtain UGW is feasible and the Barker code excited UGW can be applied in broken rail detection.