Resolution Improvement of Underground Images Using Pulse Compression

To detect the buried relics and ruins at shallow depths, we previously proposed a method using shear waves. In this study, we examine the effect of the pulse compression technique for improving the resolution of underground imaging. Using a giant magnetostriction vibrator, which can change waveforms and enable the use of the high-frequency waves, we generate both chirp waves and ordinary burst waves. To confirm the size of simulated images, which are created by emitting ordinary burst waves or chirp waves, the half-width of each image's amplitude is measured. Then, an exploration experiment is carried out where the position of buried objects is already known. The underground images obtained from the exploration experiment have almost the same size as the simulated images created by the pulse compression method. We confirm that the pulse compression technique is more suitable for improving the resolution of underground images than the hammer method and the method using burst waves.