Short-Time Fourier Transform of Deeply Located Tunnel Signatures Measured by Cross-Borehole Pulse Radar

Abstract

The pulse signatures of a deeply located dormant tunnel are measured by operating cross-borehole short-pulse radar in a well-suited tunnel test site in Korea. The relatively fast arrival of the first peak at depth of the empty tunnel, as indicated by data analysis, may play a key role in detecting the tunnel's precise location. Following short-time Fourier transform (STFT) of the data, the arrival time of the first peak is shown to be faster and more distinctive than that without STFT if the observation frequency is properly selected.