A noise reduction method for Ground Penetrating Radar signal based on wavelet transform and application in tunnel lining

One of the major limitations that hinder the use of ground penetrating radar (GPR) in civil engineering is the inevitable noise interference associated with the GPR signal. This study proposes a noise reduction technology for a GPR signal by utilizing the excellent time-frequency localization properties of a wavelet and by analysing the characteristics of the wavelet function and the principles of wavelet noise reduction. A Daubechies wavelet is selected as the wavelet function, and the wavelet decomposition and re-construction is performed on a single channel radar signal. The images of tunnel lining from GPR are compared before and after wavelet transform, and the wavelet transform processing is proved to be capable of separating noise as well as of improving the signal-to-noise ratio. The results show that wavelet transform processing is found useful to improve the recognition of image and the accuracy of radar signal interpretation.