| 摘要 |
PURPOSE:To accurately detect the position of a tunnel by recognizing the position of an underground excavator by transmitting a wave from underground and receiving the wave on the ground. CONSTITUTION:A wave, such as a single pulse wave or a continuous wave, is transmitted from a transmitting antenna provided in a tunnel 4. The wave transmitted from inside the tunnel 4 is received on the ground 1 and time difference from the time when the wave is transmitted to the time when the wave is received, that is, the phase difference between a reference signal and a received signal is measured by a phase measuring device 12. The wave is received in a plurality of positions by displacing a receiving antenna 11 and the phase difference between the reference signal and the received signal is measured in each receiving position. The position of the receiving antenna 11 where the phase difference is minimum is detected by comparing phases among respective receiving positions and the position thus detected is specified as the position just above the transmitting antenna 5.
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