Guided wave is expected as the most promising technique for rapid long-range inspection of pipes. However, signal to noise ratio is still required to be improved, especially in highly attenuative pipes covered with heat insulator and/or buried in the ground. Recently, pulse compression technique has been developed as an effective means for improving S/N ratio in the field of radar detection. In this paper, chirp pulse compression technique was applied to the long-range inspection of pipe using guided wave. The technical brief explanation about chirp pulse compression was described. Example data signals of burst wave excitation way and chirp pulse excitation way with commonly -used amplifier were reviewed with respect to unwanted side lobe. The cause of a side lobe was investigated, and the amplifier with excellent distortion property was presented to improve S/N ratio of system with quite vanishing of side lobe.
